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Configuration and TuningChernLeeWritten by MikeSmithBased on a tutorial written by MattDillonAlso based on tuning(7) written by Synopsissystem configurationsystem optimizationOne of the important aspects of &os; is proper system
configuration. This chapter explains much of the &os;
configuration process, including some of the parameters which
can be set to tune a &os; system.After reading this chapter, you will know:The basics of rc.conf configuration
and /usr/local/etc/rc.d startup
scripts.How to configure and test a network card.How to configure virtual hosts on network
devices.How to use the various configuration files in
/etc.How to tune &os; using &man.sysctl.8; variables.How to tune disk performance and modify kernel
limitations.Before reading this chapter, you should:Understand &unix; and &os; basics
().Be familiar with the basics of kernel configuration and
compilation ().Starting ServicesTomRhodesContributed by servicesMany users install third party software on &os; from the
Ports Collection and require the installed services to be
started upon system initialization. Services, such as
mail/postfix or
www/apache22 are just two of the many
software packages which may be started during system
initialization. This section explains the procedures available
for starting third party software.In &os;, most included services, such as &man.cron.8;, are
started through the system startup scripts.Extended Application ConfigurationNow that &os; includes rc.d,
configuration of application startup is easier and provides
more features. Using the key words discussed in
, applications can be set to
start after certain other services and extra flags can be
passed through /etc/rc.conf in place of
hard coded flags in the startup script. A basic script may
look similar to the following:#!/bin/sh
#
# PROVIDE: utility
# REQUIRE: DAEMON
# KEYWORD: shutdown
. /etc/rc.subr
name=utility
rcvar=utility_enable
command="/usr/local/sbin/utility"
load_rc_config $name
#
# DO NOT CHANGE THESE DEFAULT VALUES HERE
# SET THEM IN THE /etc/rc.conf FILE
#
utility_enable=${utility_enable-"NO"}
pidfile=${utility_pidfile-"/var/run/utility.pid"}
run_rc_command "$1"This script will ensure that the provided
utility will be started after the
DAEMON pseudo-service. It also provides a
method for setting and tracking the process ID
(PID).This application could then have the following line placed
in /etc/rc.conf:utility_enable="YES"This method allows for easier manipulation of command
line arguments, inclusion of the default functions provided
in /etc/rc.subr, compatibility with
&man.rcorder.8;, and provides for easier configuration via
rc.conf.Using Services to Start ServicesOther services can be started using &man.inetd.8;.
Working with &man.inetd.8; and its configuration is
described in depth in
.In some cases, it may make more sense to use
&man.cron.8; to start system services. This approach
has a number of advantages as &man.cron.8; runs these
processes as the owner of the &man.crontab.5;. This allows
regular users to start and maintain their own
applications.The @reboot feature of &man.cron.8;,
may be used in place of the time specification. This causes
the job to run when &man.cron.8; is started, normally during
system initialization.Configuring &man.cron.8;TomRhodesContributed by cronconfigurationOne of the most useful utilities in &os; is
cron. This utility runs in the
background and regularly checks
/etc/crontab for tasks to execute and
searches /var/cron/tabs for custom crontab
files. These files are used to schedule tasks which
cron runs at the specified times.
Each entry in a crontab defines a task to run and is known as a
cron job.Two different types of configuration files are used: the
system crontab, which should not be modified, and user crontabs,
which can be created and edited as needed. The format used by
these files is documented in &man.crontab.5;. The format of the
system crontab, /etc/crontab includes a
who column which does not exist in user
crontabs. In the system crontab,
cron runs the command as the user
specified in this column. In a user crontab, all commands run
as the user who created the crontab.User crontabs allow individual users to schedule their own
tasks. The root user
can also have a user crontab which can be
used to schedule tasks that do not exist in the system
crontab.Here is a sample entry from the system crontab,
/etc/crontab:
- # /etc/crontab - root's crontab for FreeBSD
+ # /etc/crontab - root's crontab for FreeBSD
#
-# $FreeBSD$
+# $FreeBSD$
#
SHELL=/bin/sh
PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin
#
#minute hour mday month wday who command
#
*/5 * * * * root /usr/libexec/atrun Lines that begin with the # character
are comments. A comment can be placed in the file as a
reminder of what and why a desired action is performed.
Comments cannot be on the same line as a command or else
they will be interpreted as part of the command; they must
be on a new line. Blank lines are ignored.The equals (=) character is used to
define any environment settings. In this example, it is
used to define the SHELL and
PATH. If the SHELL is
omitted, cron will use the
default Bourne shell. If the PATH is
omitted, the full path must be given to the command or
script to run.This line defines the seven fields used in a system
crontab: minute, hour,
mday, month,
wday, who, and
command. The minute
field is the time in minutes when the specified command will
be run, the hour is the hour when the
specified command will be run, the mday
is the day of the month, month is the
month, and wday is the day of the week.
These fields must be numeric values, representing the
twenty-four hour clock, or a *,
representing all values for that field. The
who field only exists in the system
crontab and specifies which user the command should be run
as. The last field is the command to be executed.This entry defines the values for this cron job. The
*/5, followed by several more
* characters, specifies that
/usr/libexec/atrun is invoked by
root every five
minutes of every hour, of every day and day of the week, of
every month.Commands can include any number of switches. However,
commands which extend to multiple lines need to be broken
with the backslash \ continuation
character.Creating a User CrontabTo create a user crontab, invoke
crontab in editor mode:&prompt.user; crontab -eThis will open the user's crontab using the default text
editor. The first time a user runs this command, it will open
an empty file. Once a user creates a crontab, this command
will open that file for editing.It is useful to add these lines to the top of the crontab
file in order to set the environment variables and to remember
the meanings of the fields in the crontab:SHELL=/bin/sh
PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin
# Order of crontab fields
# minute hour mday month wday commandThen add a line for each command or script to run,
specifying the time to run the command. This example runs the
specified custom Bourne shell script every day at two in the
afternoon. Since the path to the script is not specified in
PATH, the full path to the script is
given:0 14 * * * /usr/home/dru/bin/mycustomscript.shBefore using a custom script, make sure it is executable
and test it with the limited set of environment variables
set by cron. To replicate the environment that would be
used to run the above cron entry, use:env -i SHELL=/bin/sh PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin HOME=/home/dru LOGNAME=dru/usr/home/dru/bin/mycustomscript.shThe environment set by cron is discussed in
&man.crontab.5;. Checking that scripts operate correctly in
a cron environment is especially important if they include
any commands that delete files using wildcards.When finished editing the crontab, save the file. It
will automatically be installed and
cron will read the crontab and run
its cron jobs at their specified times. To list the cron jobs
in a crontab, use this command:&prompt.user; crontab -l
0 14 * * * /usr/home/dru/bin/mycustomscript.shTo remove all of the cron jobs in a user crontab:&prompt.user; crontab -r
remove crontab for dru? yManaging Services in &os;TomRhodesContributed by &os; uses the &man.rc.8; system of startup scripts during
system initialization and for managing services. The scripts
listed in /etc/rc.d provide basic services
which can be controlled with the ,
, and options to
&man.service.8;. For instance, &man.sshd.8; can be restarted
with the following command:&prompt.root; service sshd restartThis procedure can be used to start services on a running
system. Services will be started automatically at boot time
as specified in &man.rc.conf.5;. For example, to enable
&man.natd.8; at system startup, add the following line to
/etc/rc.conf:natd_enable="YES"If a line is already
present, change the NO to
YES. The &man.rc.8; scripts will
automatically load any dependent services during the next boot,
as described below.Since the &man.rc.8; system is primarily intended to start
and stop services at system startup and shutdown time, the
, and
options will only perform their action
if the appropriate /etc/rc.conf variable
is set. For instance, sshd restart will
only work if sshd_enable is set to
in /etc/rc.conf.
To , or
a service regardless of the settings
in /etc/rc.conf, these commands should be
prefixed with one. For instance, to restart
&man.sshd.8; regardless of the current
/etc/rc.conf setting, execute the following
command:&prompt.root; service sshd onerestartTo check if a service is enabled in
/etc/rc.conf, run the appropriate
&man.rc.8; script with . This example
checks to see if &man.sshd.8; is enabled in
/etc/rc.conf:&prompt.root; service sshd rcvar
# sshd
#
sshd_enable="YES"
# (default: "")The # sshd line is output from the
above command, not a
root console.To determine whether or not a service is running, use
. For instance, to verify that
&man.sshd.8; is running:&prompt.root; service sshd status
sshd is running as pid 433.In some cases, it is also possible to
a service. This attempts to send a
signal to an individual service, forcing the service to reload
its configuration files. In most cases, this means sending
the service a SIGHUP signal. Support for
this feature is not included for every service.The &man.rc.8; system is used for network services and it
also contributes to most of the system initialization. For
instance, when the
/etc/rc.d/bgfsck script is executed, it
prints out the following message:Starting background file system checks in 60 seconds.This script is used for background file system checks,
which occur only during system initialization.Many system services depend on other services to function
properly. For example, &man.yp.8; and other
RPC-based services may fail to start until
after the &man.rpcbind.8; service has started. To resolve this
issue, information about dependencies and other meta-data is
included in the comments at the top of each startup script.
The &man.rcorder.8; program is used to parse these comments
during system initialization to determine the order in which
system services should be invoked to satisfy the
dependencies.The following key word must be included in all startup
scripts as it is required by &man.rc.subr.8; to
enable the startup script:PROVIDE: Specifies the services this
file provides.The following key words may be included at the top of each
startup script. They are not strictly necessary, but are
useful as hints to &man.rcorder.8;:REQUIRE: Lists services which are
required for this service. The script containing this key
word will run after the specified
services.BEFORE: Lists services which depend
on this service. The script containing this key word will
run before the specified
services.By carefully setting these keywords for each startup script,
an administrator has a fine-grained level of control of the
startup order of the scripts, without the need for
runlevels used by some &unix; operating
systems.Additional information can be found in &man.rc.8; and
&man.rc.subr.8;. Refer to this article
for instructions on how to create custom &man.rc.8;
scripts.Managing System-Specific Configurationrc filesrc.confThe principal location for system configuration
information is /etc/rc.conf. This file
contains a wide range of configuration information and it is
read at system startup to configure the system. It provides
the configuration information for the
rc* files.The entries in /etc/rc.conf override
the default settings in
/etc/defaults/rc.conf. The file
containing the default settings should not be edited.
Instead, all system-specific changes should be made to
/etc/rc.conf.A number of strategies may be applied in clustered
applications to separate site-wide configuration from
system-specific configuration in order to reduce
administration overhead. The recommended approach is to place
system-specific configuration into
/etc/rc.conf.local. For example, these
entries in /etc/rc.conf apply to all
systems:sshd_enable="YES"
keyrate="fast"
defaultrouter="10.1.1.254"Whereas these entries in
/etc/rc.conf.local apply to this system
only:hostname="node1.example.org"
ifconfig_fxp0="inet 10.1.1.1/8"Distribute /etc/rc.conf to every
system using an application such as
rsync or
puppet, while
/etc/rc.conf.local remains
unique.Upgrading the system will not overwrite
/etc/rc.conf, so system configuration
information will not be lost.Both /etc/rc.conf and
/etc/rc.conf.local
are parsed by &man.sh.1;. This allows system operators to
create complex configuration scenarios. Refer to
&man.rc.conf.5; for further information on this
topic.Setting Up Network Interface CardsMarcFonvieilleContributed by network cardsconfigurationAdding and configuring a network interface card
(NIC) is a common task for any &os;
administrator.Locating the Correct Drivernetwork cardsdriverFirst, determine the model of the NIC
and the chip it uses. &os; supports a wide variety of
NICs. Check the Hardware Compatibility
List for the &os; release to see if the NIC
is supported.If the NIC is supported, determine
the name of the &os; driver for the NIC.
Refer to /usr/src/sys/conf/NOTES and
/usr/src/sys/arch/conf/NOTES
for the list of NIC drivers with some
information about the supported chipsets. When in doubt, read
the manual page of the driver as it will provide more
information about the supported hardware and any known
limitations of the driver.The drivers for common NICs are already
present in the GENERIC kernel, meaning
the NIC should be probed during boot. The
system's boot messages can be viewed by typing
more /var/run/dmesg.boot and using the
spacebar to scroll through the text. In this example, two
Ethernet NICs using the &man.dc.4; driver
are present on the system:dc0: <82c169 PNIC 10/100BaseTX> port 0xa000-0xa0ff mem 0xd3800000-0xd38
000ff irq 15 at device 11.0 on pci0
miibus0: <MII bus> on dc0
bmtphy0: <BCM5201 10/100baseTX PHY> PHY 1 on miibus0
bmtphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
dc0: Ethernet address: 00:a0:cc:da:da:da
dc0: [ITHREAD]
dc1: <82c169 PNIC 10/100BaseTX> port 0x9800-0x98ff mem 0xd3000000-0xd30
000ff irq 11 at device 12.0 on pci0
miibus1: <MII bus> on dc1
bmtphy1: <BCM5201 10/100baseTX PHY> PHY 1 on miibus1
bmtphy1: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
dc1: Ethernet address: 00:a0:cc:da:da:db
dc1: [ITHREAD]If the driver for the NIC is not
present in GENERIC, but a driver is
available, the driver will need to be loaded before the
NIC can be configured and used. This may
be accomplished in one of two ways:The easiest way is to load a kernel module for the
NIC using &man.kldload.8;. To also
automatically load the driver at boot time, add the
appropriate line to
/boot/loader.conf. Not all
NIC drivers are available as
modules.Alternatively, statically compile support for the
NIC into a custom kernel. Refer to
/usr/src/sys/conf/NOTES,
/usr/src/sys/arch/conf/NOTES
and the manual page of the driver to determine which line
to add to the custom kernel configuration file. For more
information about recompiling the kernel, refer to . If the NIC
was detected at boot, the kernel does not need to be
recompiled.Using &windows; NDIS DriversNDISNDISulator&windows; driversµsoft.windows;device driversKLD (kernel loadable
object)Unfortunately, there are still many vendors that do not
provide schematics for their drivers to the open source
community because they regard such information as trade
secrets. Consequently, the developers of &os; and other
operating systems are left with two choices: develop the
drivers by a long and pain-staking process of reverse
engineering or using the existing driver binaries available
for µsoft.windows; platforms.&os; provides native support for the
Network Driver Interface Specification
(NDIS). It includes &man.ndisgen.8;
which can be used to convert a &windowsxp; driver into a
format that can be used on &os;. Because the &man.ndis.4;
driver uses a &windowsxp; binary, it only runs on &i386;
and amd64 systems. PCI, CardBus,
PCMCIA, and USB
devices are supported.To use &man.ndisgen.8;, three things are needed:&os; kernel sources.A &windowsxp; driver binary with a
.SYS extension.A &windowsxp; driver configuration file with a
.INF extension.Download the .SYS and
.INF files for the specific
NIC. Generally, these can be found on
the driver CD or at the vendor's website. The following
examples use W32DRIVER.SYS and
W32DRIVER.INF.The driver bit width must match the version of &os;.
For &os;/i386, use a &windows; 32-bit driver. For
&os;/amd64, a &windows; 64-bit driver is needed.The next step is to compile the driver binary into a
loadable kernel module. As
root, use
&man.ndisgen.8;:&prompt.root; ndisgen /path/to/W32DRIVER.INF/path/to/W32DRIVER.SYSThis command is interactive and prompts for any extra
information it requires. A new kernel module will be
generated in the current directory. Use &man.kldload.8;
to load the new module:&prompt.root; kldload ./W32DRIVER_SYS.koIn addition to the generated kernel module, the
ndis.ko and
if_ndis.ko modules must be loaded.
This should happen automatically when any module that
depends on &man.ndis.4; is loaded. If not, load them
manually, using the following commands:&prompt.root; kldload ndis
&prompt.root; kldload if_ndisThe first command loads the &man.ndis.4; miniport driver
wrapper and the second loads the generated
NIC driver.Check &man.dmesg.8; to see if there were any load
errors. If all went well, the output should be similar to
the following:ndis0: <Wireless-G PCI Adapter> mem 0xf4100000-0xf4101fff irq 3 at device 8.0 on pci1
ndis0: NDIS API version: 5.0
ndis0: Ethernet address: 0a:b1:2c:d3:4e:f5
ndis0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
ndis0: 11g rates: 6Mbps 9Mbps 12Mbps 18Mbps 36Mbps 48Mbps 54MbpsFrom here, ndis0 can be
configured like any other NIC.To configure the system to load the &man.ndis.4; modules
at boot time, copy the generated module,
W32DRIVER_SYS.ko, to
/boot/modules. Then, add the following
line to /boot/loader.conf:W32DRIVER_SYS_load="YES"Configuring the Network Cardnetwork cardsconfigurationOnce the right driver is loaded for the
NIC, the card needs to be configured. It
may have been configured at installation time by
&man.bsdinstall.8;.To display the NIC configuration,
enter the following command:&prompt.user; ifconfig
dc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=80008<VLAN_MTU,LINKSTATE>
ether 00:a0:cc:da:da:da
inet 192.168.1.3 netmask 0xffffff00 broadcast 192.168.1.255
media: Ethernet autoselect (100baseTX <full-duplex>)
status: active
dc1: flags=8802<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=80008<VLAN_MTU,LINKSTATE>
ether 00:a0:cc:da:da:db
inet 10.0.0.1 netmask 0xffffff00 broadcast 10.0.0.255
media: Ethernet 10baseT/UTP
status: no carrier
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
options=3<RXCSUM,TXCSUM>
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x4
inet6 ::1 prefixlen 128
inet 127.0.0.1 netmask 0xff000000
nd6 options=3<PERFORMNUD,ACCEPT_RTADV>In this example, the following devices were
displayed:dc0: The first Ethernet
interface.dc1: The second Ethernet
interface.lo0: The loopback
device.&os; uses the driver name followed by the order in which
the card is detected at boot to name the
NIC. For example,
sis2 is the third
NIC on the system using the &man.sis.4;
driver.In this example, dc0 is up and
running. The key indicators are:UP means that the card is
configured and ready.The card has an Internet (inet)
address, 192.168.1.3.It has a valid subnet mask
(netmask), where
0xffffff00 is the
same as 255.255.255.0.It has a valid broadcast address, 192.168.1.255.The MAC address of the card
(ether) is 00:a0:cc:da:da:da.The physical media selection is on autoselection mode
(media: Ethernet autoselect (100baseTX
<full-duplex>)). In this example,
dc1 is configured to run with
10baseT/UTP media. For more
information on available media types for a driver, refer
to its manual page.The status of the link (status) is
active, indicating that the carrier
signal is detected. For dc1, the
status: no carrier status is normal
when an Ethernet cable is not plugged into the
card.If the &man.ifconfig.8; output had shown something similar
to:dc0: flags=8843<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=80008<VLAN_MTU,LINKSTATE>
ether 00:a0:cc:da:da:da
media: Ethernet autoselect (100baseTX <full-duplex>)
status: activeit would indicate the card has not been configured.The card must be configured as
root. The
NIC configuration can be performed from the
command line with &man.ifconfig.8; but will not persist after
a reboot unless the configuration is also added to
/etc/rc.conf. If a
DHCP server is present on the LAN,
just add this line:ifconfig_dc0="DHCP"Replace dc0 with the correct value
for the system.The line added, then, follow the instructions given in
.If the network was configured during installation, some
entries for the NIC(s) may be already
present. Double check /etc/rc.conf
before adding any lines.In the case, there is no DHCP server,
the NIC(s) have to be configured manually.
Add a line for each NIC present on the
system, as seen in this example:ifconfig_dc0="inet 192.168.1.3 netmask 255.255.255.0"
ifconfig_dc1="inet 10.0.0.1 netmask 255.255.255.0 media 10baseT/UTP"Replace dc0 and
dc1 and the IP
address information with the correct values for the system.
Refer to the man page for the driver, &man.ifconfig.8;, and
&man.rc.conf.5; for more details about the allowed options and
the syntax of /etc/rc.conf.If the network is not using DNS, edit
/etc/hosts to add the names and
IP addresses of the hosts on the
LAN, if they are not already there. For
more information, refer to &man.hosts.5; and to
/usr/share/examples/etc/hosts.If there is no DHCP server and
access to the Internet is needed, manually configure the
default gateway and the nameserver:&prompt.root; echo 'defaultrouter="your_default_router"' >> /etc/rc.conf
&prompt.root; echo 'nameserver your_DNS_server' >> /etc/resolv.confTesting and TroubleshootingOnce the necessary changes to
/etc/rc.conf are saved, a reboot can be
used to test the network configuration and to verify that the
system restarts without any configuration errors.
Alternatively, apply the settings to the networking system
with this command:&prompt.root; service netif restartIf a default gateway has been set in
/etc/rc.conf, also issue this
command:&prompt.root; service routing restartOnce the networking system has been relaunched, test the
NICs.Testing the Ethernet Cardnetwork cardstestingTo verify that an Ethernet card is configured correctly,
&man.ping.8; the interface itself, and then &man.ping.8;
another machine on the LAN:&prompt.user; ping -c5 192.168.1.3
PING 192.168.1.3 (192.168.1.3): 56 data bytes
64 bytes from 192.168.1.3: icmp_seq=0 ttl=64 time=0.082 ms
64 bytes from 192.168.1.3: icmp_seq=1 ttl=64 time=0.074 ms
64 bytes from 192.168.1.3: icmp_seq=2 ttl=64 time=0.076 ms
64 bytes from 192.168.1.3: icmp_seq=3 ttl=64 time=0.108 ms
64 bytes from 192.168.1.3: icmp_seq=4 ttl=64 time=0.076 ms
--- 192.168.1.3 ping statistics ---
5 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.074/0.083/0.108/0.013 ms&prompt.user; ping -c5 192.168.1.2
PING 192.168.1.2 (192.168.1.2): 56 data bytes
64 bytes from 192.168.1.2: icmp_seq=0 ttl=64 time=0.726 ms
64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=0.766 ms
64 bytes from 192.168.1.2: icmp_seq=2 ttl=64 time=0.700 ms
64 bytes from 192.168.1.2: icmp_seq=3 ttl=64 time=0.747 ms
64 bytes from 192.168.1.2: icmp_seq=4 ttl=64 time=0.704 ms
--- 192.168.1.2 ping statistics ---
5 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.700/0.729/0.766/0.025 msTo test network resolution, use the host name instead
of the IP address. If there is no
DNS server on the network,
/etc/hosts must first be
configured. To this purpose, edit
/etc/hosts to add the names and
IP addresses of the hosts on the
LAN, if they are not already there. For
more information, refer to &man.hosts.5; and to
/usr/share/examples/etc/hosts.Troubleshootingnetwork cardstroubleshootingWhen troubleshooting hardware and software
configurations, check the simple things first. Is the
network cable plugged in? Are the network services properly
configured? Is the firewall configured correctly? Is the
NIC supported by &os;? Before sending
a bug report, always check the Hardware Notes, update the
version of &os; to the latest STABLE version, check the
mailing list archives, and search the Internet.If the card works, yet performance is poor, read
through &man.tuning.7;. Also, check the network
configuration as incorrect network settings can cause slow
connections.Some users experience one or two
device timeout messages, which is
normal for some cards. If they continue, or are bothersome,
determine if the device is conflicting with another device.
Double check the cable connections. Consider trying another
card.To resolve watchdog timeout
errors, first check the network cable. Many cards
require a PCI slot which supports bus
mastering. On some old motherboards, only one
PCI slot allows it, usually slot 0.
Check the NIC and the motherboard
documentation to determine if that may be the
problem.No route to host messages occur
if the system is unable to route a packet to the destination
host. This can happen if no default route is specified or
if a cable is unplugged. Check the output of
netstat -rn and make sure there is a
valid route to the host. If there is not, read
.ping: sendto: Permission denied
error messages are often caused by a misconfigured firewall.
If a firewall is enabled on &os; but no rules have been
defined, the default policy is to deny all traffic, even
&man.ping.8;. Refer to
for more information.Sometimes performance of the card is poor or below
average. In these cases, try setting the media
selection mode from autoselect to the
correct media selection. While this works for most
hardware, it may or may not resolve the issue. Again,
check all the network settings, and refer to
&man.tuning.7;.Virtual Hostsvirtual hostsIP
aliasesA common use of &os; is virtual site hosting, where one
server appears to the network as many servers. This is achieved
by assigning multiple network addresses to a single
interface.A given network interface has one real
address, and may have any number of alias
addresses. These aliases are normally added by placing alias
entries in /etc/rc.conf, as seen in this
example:ifconfig_fxp0_alias0="inet xxx.xxx.xxx.xxx netmask xxx.xxx.xxx.xxx"Alias entries must start with
alias0 using a
sequential number such as
alias0, alias1,
and so on. The configuration process will stop at the first
missing number.The calculation of alias netmasks is important. For a
given interface, there must be one address which correctly
represents the network's netmask. Any other addresses which
fall within this network must have a netmask of all
1s, expressed as either
255.255.255.255 or
0xffffffff.For example, consider the case where the
fxp0 interface is connected to two
networks: 10.1.1.0
with a netmask of
255.255.255.0 and
202.0.75.16 with a
netmask of
255.255.255.240. The
system is to be configured to appear in the ranges
10.1.1.1 through
10.1.1.5 and
202.0.75.17 through
202.0.75.20. Only
the first address in a given network range should have a real
netmask. All the rest
(10.1.1.2 through
10.1.1.5 and
202.0.75.18 through
202.0.75.20) must be
configured with a netmask of
255.255.255.255.The following /etc/rc.conf entries
configure the adapter correctly for this scenario:ifconfig_fxp0="inet 10.1.1.1 netmask 255.255.255.0"
ifconfig_fxp0_alias0="inet 10.1.1.2 netmask 255.255.255.255"
ifconfig_fxp0_alias1="inet 10.1.1.3 netmask 255.255.255.255"
ifconfig_fxp0_alias2="inet 10.1.1.4 netmask 255.255.255.255"
ifconfig_fxp0_alias3="inet 10.1.1.5 netmask 255.255.255.255"
ifconfig_fxp0_alias4="inet 202.0.75.17 netmask 255.255.255.240"
ifconfig_fxp0_alias5="inet 202.0.75.18 netmask 255.255.255.255"
ifconfig_fxp0_alias6="inet 202.0.75.19 netmask 255.255.255.255"
ifconfig_fxp0_alias7="inet 202.0.75.20 netmask 255.255.255.255"A simpler way to express this is with a space-separated list
of IP address ranges. The first address
will be given the
indicated subnet mask and the additional addresses will have a
subnet mask of 255.255.255.255.ifconfig_fxp0_aliases="inet 10.1.1.1-5/24 inet 202.0.75.17-20/28"Configuring System LoggingNiclasZeisingContributed by system loggingsyslog&man.syslogd.8;Generating and reading system logs is an important aspect of
system administration. The information in system logs can be
used to detect hardware and software issues as well as
application and system configuration errors. This information
also plays an important role in security auditing and incident
response. Most system daemons and applications will generate
log entries.&os; provides a system logger,
syslogd, to manage logging. By
default, syslogd is started when the
system boots. This is controlled by the variable
syslogd_enable in
/etc/rc.conf. There are numerous
application arguments that can be set using
syslogd_flags in
/etc/rc.conf. Refer to &man.syslogd.8; for
more information on the available arguments.This section describes how to configure the &os; system
logger for both local and remote logging and how to perform log
rotation and log management.Configuring Local Loggingsyslog.confThe configuration file,
/etc/syslog.conf, controls what
syslogd does with log entries as
they are received. There are several parameters to control
the handling of incoming events. The
facility describes which subsystem
generated the message, such as the kernel or a daemon, and the
level describes the severity of the
event that occurred. This makes it possible to configure if
and where a log message is logged, depending on the facility
and level. It is also possible to take action depending on
the application that sent the message, and in the case of
remote logging, the hostname of the machine generating the
logging event.This configuration file contains one line per action,
where the syntax for each line is a selector field followed by
an action field. The syntax of the selector field is
facility.level which will match log
messages from facility at level
level or higher. It is also
possible to add an optional comparison flag before the level
to specify more precisely what is logged. Multiple selector
fields can be used for the same action, and are separated with
a semicolon (;). Using
* will match everything. The action field
denotes where to send the log message, such as to a file or
remote log host. As an example, here is the default
syslog.conf from &os;:
- # $&os;$
+ # $&os;$
#
# Spaces ARE valid field separators in this file. However,
# other *nix-like systems still insist on using tabs as field
# separators. If you are sharing this file between systems, you
# may want to use only tabs as field separators here.
# Consult the syslog.conf(5) manpage.
*.err;kern.warning;auth.notice;mail.crit /dev/console
*.notice;authpriv.none;kern.debug;lpr.info;mail.crit;news.err /var/log/messages
security.* /var/log/security
auth.info;authpriv.info /var/log/auth.log
mail.info /var/log/maillog
lpr.info /var/log/lpd-errs
ftp.info /var/log/xferlog
cron.* /var/log/cron
!-devd
*.=debug /var/log/debug.log
*.emerg *
# uncomment this to log all writes to /dev/console to /var/log/console.log
#console.info /var/log/console.log
# uncomment this to enable logging of all log messages to /var/log/all.log
# touch /var/log/all.log and chmod it to mode 600 before it will work
#*.* /var/log/all.log
# uncomment this to enable logging to a remote loghost named loghost
#*.* @loghost
# uncomment these if you're running inn
# news.crit /var/log/news/news.crit
# news.err /var/log/news/news.err
# news.notice /var/log/news/news.notice
# Uncomment this if you wish to see messages produced by devd
# !devd
# *.>=info
!ppp
*.* /var/log/ppp.log
!*In this example:Line 8 matches all messages with a level of
err or higher, as well as
kern.warning,
auth.notice and
mail.crit, and sends these log messages
to the console
(/dev/console).Line 12 matches all messages from the
mail facility at level
info or above and logs the messages to
/var/log/maillog.Line 17 uses a comparison flag (=)
to only match messages at level debug
and logs them to
/var/log/debug.log.Line 33 is an example usage of a program
specification. This makes the rules following it only
valid for the specified program. In this case, only the
messages generated by ppp are
logged to /var/log/ppp.log.The available levels, in order from most to least
critical are emerg,
alert, crit,
err, warning,
notice, info, and
debug.The facilities, in no particular order, are
auth, authpriv,
console, cron,
daemon, ftp,
kern, lpr,
mail, mark,
news, security,
syslog, user,
uucp, and local0 through
local7. Be aware that other operating
systems might have different facilities.To log everything of level notice and
higher to /var/log/daemon.log, add the
following entry:daemon.notice /var/log/daemon.logFor more information about the different levels and
facilities, refer to &man.syslog.3; and &man.syslogd.8;.
For more information about
/etc/syslog.conf, its syntax, and more
advanced usage examples, see &man.syslog.conf.5;.Log Management and Rotationnewsyslognewsyslog.conflog rotationlog managementLog files can grow quickly, taking up disk space and
making it more difficult to locate useful information. Log
management attempts to mitigate this. In &os;,
newsyslog is used to manage log
files. This built-in program periodically rotates and
compresses log files, and optionally creates missing log files
and signals programs when log files are moved. The log files
may be generated by syslogd or by
any other program which generates log files. While
newsyslog is normally run from
&man.cron.8;, it is not a system daemon. In the default
configuration, it runs every hour.To know which actions to take,
newsyslog reads its configuration
file, /etc/newsyslog.conf. This file
contains one line for each log file that
newsyslog manages. Each line
states the file owner, permissions, when to rotate that file,
optional flags that affect log rotation, such as compression,
and programs to signal when the log is rotated. Here is the
default configuration in &os;:
- # configuration file for newsyslog
-# $FreeBSD$
+ # configuration file for newsyslog
+# $FreeBSD$
#
# Entries which do not specify the '/pid_file' field will cause the
# syslogd process to be signalled when that log file is rotated. This
# action is only appropriate for log files which are written to by the
# syslogd process (ie, files listed in /etc/syslog.conf). If there
# is no process which needs to be signalled when a given log file is
# rotated, then the entry for that file should include the 'N' flag.
#
# The 'flags' field is one or more of the letters: BCDGJNUXZ or a '-'.
#
# Note: some sites will want to select more restrictive protections than the
# defaults. In particular, it may be desirable to switch many of the 644
# entries to 640 or 600. For example, some sites will consider the
# contents of maillog, messages, and lpd-errs to be confidential. In the
# future, these defaults may change to more conservative ones.
#
# logfilename [owner:group] mode count size when flags [/pid_file] [sig_num]
/var/log/all.log 600 7 * @T00 J
/var/log/amd.log 644 7 100 * J
/var/log/auth.log 600 7 100 @0101T JC
/var/log/console.log 600 5 100 * J
/var/log/cron 600 3 100 * JC
/var/log/daily.log 640 7 * @T00 JN
/var/log/debug.log 600 7 100 * JC
/var/log/kerberos.log 600 7 100 * J
/var/log/lpd-errs 644 7 100 * JC
/var/log/maillog 640 7 * @T00 JC
/var/log/messages 644 5 100 @0101T JC
/var/log/monthly.log 640 12 * $M1D0 JN
/var/log/pflog 600 3 100 * JB /var/run/pflogd.pid
/var/log/ppp.log root:network 640 3 100 * JC
/var/log/devd.log 644 3 100 * JC
/var/log/security 600 10 100 * JC
/var/log/sendmail.st 640 10 * 168 B
/var/log/utx.log 644 3 * @01T05 B
/var/log/weekly.log 640 5 1 $W6D0 JN
/var/log/xferlog 600 7 100 * JCEach line starts with the name of the log to be rotated,
optionally followed by an owner and group for both rotated and
newly created files. The mode field sets
the permissions on the log file and count
denotes how many rotated log files should be kept. The
size and when fields
tell newsyslog when to rotate the
file. A log file is rotated when either its size is larger
than the size field or when the time in the
when field has passed. An asterisk
(*) means that this field is ignored. The
flags field gives further
instructions, such as how to compress the rotated file or to
create the log file if it is missing. The last two fields are
optional and specify the name of the Process ID
(PID) file of a process and a signal number
to send to that process when the file is rotated.For more information on all fields, valid flags, and how
to specify the rotation time, refer to &man.newsyslog.conf.5;.
Since newsyslog is run from
&man.cron.8;, it cannot rotate files more often than it is
scheduled to run from &man.cron.8;.Configuring Remote LoggingTomRhodesContributed by Monitoring the log files of multiple hosts can become
unwieldy as the number of systems increases. Configuring
centralized logging can reduce some of the administrative
burden of log file administration.In &os;, centralized log file aggregation, merging, and
rotation can be configured using
syslogd and
newsyslog. This section
demonstrates an example configuration, where host
A, named logserv.example.com, will
collect logging information for the local network. Host
B, named logclient.example.com,
will be configured to pass logging information to the logging
server.Log Server ConfigurationA log server is a system that has been configured to
accept logging information from other hosts. Before
configuring a log server, check the following:If there is a firewall between the logging server
and any logging clients, ensure that the firewall
ruleset allows UDP port 514 for both
the clients and the server.The logging server and all client machines must
have forward and reverse entries in the local
DNS. If the network does not have a
DNS server, create entries in each
system's /etc/hosts. Proper name
resolution is required so that log entries are not
rejected by the logging server.On the log server, edit
/etc/syslog.conf to specify the name of
the client to receive log entries from, the logging facility
to be used, and the name of the log to store the host's log
entries. This example adds the hostname of
B, logs all facilities, and stores
the log entries in
/var/log/logclient.log.Sample Log Server Configuration+logclient.example.com
*.* /var/log/logclient.logWhen adding multiple log clients, add a similar two-line
entry for each client. More information about the available
facilities may be found in &man.syslog.conf.5;.Next, configure
/etc/rc.conf:syslogd_enable="YES"
syslogd_flags="-a logclient.example.com -v -v"The first entry starts
syslogd at system boot. The
second entry allows log entries from the specified client.
The increases the verbosity of logged
messages. This is useful for tweaking facilities as
administrators are able to see what type of messages are
being logged under each facility.Multiple options may be specified to
allow logging from multiple clients. IP
addresses and whole netblocks may also be specified. Refer
to &man.syslogd.8; for a full list of possible
options.Finally, create the log file:&prompt.root; touch /var/log/logclient.logAt this point, syslogd should
be restarted and verified:&prompt.root; service syslogd restart
&prompt.root; pgrep syslogIf a PID is returned, the server
restarted successfully, and client configuration can begin.
If the server did not restart, consult
/var/log/messages for the error.Log Client ConfigurationA logging client sends log entries to a logging server
on the network. The client also keeps a local copy of its
own logs.Once a logging server has been configured, edit
/etc/rc.conf on the logging
client:syslogd_enable="YES"
syslogd_flags="-s -v -v"The first entry enables
syslogd on boot up. The second
entry prevents logs from being accepted by this client from
other hosts () and increases the
verbosity of logged messages.Next, define the logging server in the client's
/etc/syslog.conf. In this example, all
logged facilities are sent to a remote system, denoted by
the @ symbol, with the specified
hostname:*.* @logserv.example.comAfter saving the edit, restart
syslogd for the changes to take
effect:&prompt.root; service syslogd restartTo test that log messages are being sent across the
network, use &man.logger.1; on the client to send a message
to syslogd:&prompt.root; logger "Test message from logclient"This message should now exist both in
/var/log/messages on the client and
/var/log/logclient.log on the log
server.Debugging Log ServersIf no messages are being received on the log server, the
cause is most likely a network connectivity issue, a
hostname resolution issue, or a typo in a configuration
file. To isolate the cause, ensure that both the logging
server and the logging client are able to
ping each other using the hostname
specified in their /etc/rc.conf. If
this fails, check the network cabling, the firewall ruleset,
and the hostname entries in the DNS
server or /etc/hosts on both the
logging server and clients. Repeat until the
ping is successful from both
hosts.If the ping succeeds on both hosts
but log messages are still not being received, temporarily
increase logging verbosity to narrow down the configuration
issue. In the following example,
/var/log/logclient.log on the logging
server is empty and /var/log/messages
on the logging client does not indicate a reason for the
failure. To increase debugging output, edit the
syslogd_flags entry on the logging server
and issue a restart:syslogd_flags="-d -a logclient.example.com -v -v"&prompt.root; service syslogd restartDebugging data similar to the following will flash on
the console immediately after the restart:logmsg: pri 56, flags 4, from logserv.example.com, msg syslogd: restart
syslogd: restarted
logmsg: pri 6, flags 4, from logserv.example.com, msg syslogd: kernel boot file is /boot/kernel/kernel
Logging to FILE /var/log/messages
syslogd: kernel boot file is /boot/kernel/kernel
cvthname(192.168.1.10)
validate: dgram from IP 192.168.1.10, port 514, name logclient.example.com;
rejected in rule 0 due to name mismatch.In this example, the log messages are being rejected due
to a typo which results in a hostname mismatch. The
client's hostname should be logclient,
not logclien. Fix the typo, issue a
restart, and verify the results:&prompt.root; service syslogd restart
logmsg: pri 56, flags 4, from logserv.example.com, msg syslogd: restart
syslogd: restarted
logmsg: pri 6, flags 4, from logserv.example.com, msg syslogd: kernel boot file is /boot/kernel/kernel
syslogd: kernel boot file is /boot/kernel/kernel
logmsg: pri 166, flags 17, from logserv.example.com,
msg Dec 10 20:55:02 <syslog.err> logserv.example.com syslogd: exiting on signal 2
cvthname(192.168.1.10)
validate: dgram from IP 192.168.1.10, port 514, name logclient.example.com;
accepted in rule 0.
logmsg: pri 15, flags 0, from logclient.example.com, msg Dec 11 02:01:28 trhodes: Test message 2
Logging to FILE /var/log/logclient.log
Logging to FILE /var/log/messagesAt this point, the messages are being properly received
and placed in the correct file.Security ConsiderationsAs with any network service, security requirements
should be considered before implementing a logging server.
Log files may contain sensitive data about services enabled
on the local host, user accounts, and configuration data.
Network data sent from the client to the server will not be
encrypted or password protected. If a need for encryption
exists, consider using security/stunnel,
which will transmit the logging data over an encrypted
tunnel.Local security is also an issue. Log files are not
encrypted during use or after log rotation. Local users may
access log files to gain additional insight into system
configuration. Setting proper permissions on log files is
critical. The built-in log rotator,
newsyslog, supports setting
permissions on newly created and rotated log files. Setting
log files to mode 600 should prevent
unwanted access by local users. Refer to
&man.newsyslog.conf.5; for additional information.Configuration Files/etc
LayoutThere are a number of directories in which configuration
information is kept. These include:/etcGeneric system-specific configuration
information./etc/defaultsDefault versions of system configuration
files./etc/mailExtra &man.sendmail.8; configuration and other
MTA configuration files./etc/pppConfiguration for both user- and kernel-ppp
programs./etc/namedbDefault location for &man.named.8; data.
Normally named.conf and zone
files are stored here./usr/local/etcConfiguration files for installed applications.
May contain per-application subdirectories./usr/local/etc/rc.d&man.rc.8; scripts for installed
applications./var/dbAutomatically generated system-specific database
files, such as the package database and the
&man.locate.1; database.HostnameshostnameDNS/etc/resolv.confresolv.confHow a &os; system accesses the Internet Domain Name
System (DNS) is controlled by
&man.resolv.conf.5;.The most common entries to
/etc/resolv.conf are:nameserverThe IP address of a name
server the resolver should query. The servers are
queried in the order listed with a maximum of
three.searchSearch list for hostname lookup. This is
normally determined by the domain of the local
hostname.domainThe local domain name.A typical /etc/resolv.conf looks
like this:search example.com
nameserver 147.11.1.11
nameserver 147.11.100.30Only one of the search and
domain options should be used.When using DHCP, &man.dhclient.8;
usually rewrites /etc/resolv.conf
with information received from the DHCP
server./etc/hostshosts/etc/hosts is a simple text
database which works in conjunction with
DNS and
NIS to provide host name to
IP address mappings. Entries for local
computers connected via a LAN can be
added to this file for simplistic naming purposes instead
of setting up a &man.named.8; server. Additionally,
/etc/hosts can be used to provide a
local record of Internet names, reducing the need to query
external DNS servers for commonly
accessed names.
- # $&os;$
+ # $&os;$
#
#
# Host Database
#
# This file should contain the addresses and aliases for local hosts that
# share this file. Replace 'my.domain' below with the domainname of your
# machine.
#
# In the presence of the domain name service or NIS, this file may
# not be consulted at all; see /etc/nsswitch.conf for the resolution order.
#
#
::1 localhost localhost.my.domain
127.0.0.1 localhost localhost.my.domain
#
# Imaginary network.
#10.0.0.2 myname.my.domain myname
#10.0.0.3 myfriend.my.domain myfriend
#
# According to RFC 1918, you can use the following IP networks for
# private nets which will never be connected to the Internet:
#
# 10.0.0.0 - 10.255.255.255
# 172.16.0.0 - 172.31.255.255
# 192.168.0.0 - 192.168.255.255
#
# In case you want to be able to connect to the Internet, you need
# real official assigned numbers. Do not try to invent your own network
# numbers but instead get one from your network provider (if any) or
# from your regional registry (ARIN, APNIC, LACNIC, RIPE NCC, or AfriNIC.)
#The format of /etc/hosts is as
follows:[Internet address] [official hostname] [alias1] [alias2] ...For example:10.0.0.1 myRealHostname.example.com myRealHostname foobar1 foobar2Consult &man.hosts.5; for more information.Tuning with &man.sysctl.8;sysctltuningwith sysctl&man.sysctl.8; is used to make changes to a running &os;
system. This includes many advanced options of the
TCP/IP stack and virtual memory system
that can dramatically improve performance for an experienced
system administrator. Over five hundred system variables can
be read and set using &man.sysctl.8;.At its core, &man.sysctl.8; serves two functions: to read
and to modify system settings.To view all readable variables:&prompt.user; sysctl -aTo read a particular variable, specify its name:&prompt.user; sysctl kern.maxproc
kern.maxproc: 1044To set a particular variable, use the
variable=value
syntax:&prompt.root; sysctl kern.maxfiles=5000
kern.maxfiles: 2088 -> 5000Settings of sysctl variables are usually either strings,
numbers, or booleans, where a boolean is 1
for yes or 0 for no.To automatically set some variables each time the machine
boots, add them to /etc/sysctl.conf. For
more information, refer to &man.sysctl.conf.5; and
.sysctl.confsysctl.confsysctlThe configuration file for &man.sysctl.8;,
/etc/sysctl.conf, looks much like
/etc/rc.conf. Values are set in a
variable=value form. The specified values
are set after the system goes into multi-user mode. Not all
variables are settable in this mode.For example, to turn off logging of fatal signal exits
and prevent users from seeing processes started by other
users, the following tunables can be set in
/etc/sysctl.conf:# Do not log fatal signal exits (e.g., sig 11)
kern.logsigexit=0
# Prevent users from seeing information about processes that
# are being run under another UID.
security.bsd.see_other_uids=0&man.sysctl.8; Read-onlyTomRhodesContributed by In some cases it may be desirable to modify read-only
&man.sysctl.8; values, which will require a reboot of the
system.For instance, on some laptop models the &man.cardbus.4;
device will not probe memory ranges and will fail with errors
similar to:cbb0: Could not map register memory
device_probe_and_attach: cbb0 attach returned 12The fix requires the modification of a read-only
&man.sysctl.8; setting. Add
to
/boot/loader.conf and reboot. Now
&man.cardbus.4; should work properly.Tuning DisksThe following section will discuss various tuning
mechanisms and options which may be applied to disk
devices. In many cases, disks with mechanical parts,
such as SCSI drives, will be the
bottleneck driving down the overall system performance. While
a solution is to install a drive without mechanical parts,
such as a solid state drive, mechanical drives are not
going away anytime in the near future. When tuning disks,
it is advisable to utilize the features of the &man.iostat.8;
command to test various changes to the system. This
command will allow the user to obtain valuable information
on system IO.Sysctl Variablesvfs.vmiodirenablevfs.vmiodirenableThe vfs.vmiodirenable &man.sysctl.8;
variable
may be set to either 0 (off) or
1 (on). It is set to
1 by default. This variable controls
how directories are cached by the system. Most directories
are small, using just a single fragment (typically 1 K)
in the file system and typically 512 bytes in the
buffer cache. With this variable turned off, the buffer
cache will only cache a fixed number of directories, even
if the system has a huge amount of memory. When turned on,
this &man.sysctl.8; allows the buffer cache to use the
VM page cache to cache the directories,
making all the memory available for caching directories.
However, the minimum in-core memory used to cache a
directory is the physical page size (typically 4 K)
rather than 512 bytes. Keeping this option enabled
is recommended if the system is running any services which
manipulate large numbers of files. Such services can
include web caches, large mail systems, and news systems.
Keeping this option on will generally not reduce
performance, even with the wasted memory, but one should
experiment to find out.vfs.write_behindvfs.write_behindThe vfs.write_behind &man.sysctl.8;
variable
defaults to 1 (on). This tells the file
system to issue media writes as full clusters are collected,
which typically occurs when writing large sequential files.
This avoids saturating the buffer cache with dirty buffers
when it would not benefit I/O performance. However, this
may stall processes and under certain circumstances should
be turned off.vfs.hirunningspacevfs.hirunningspaceThe vfs.hirunningspace &man.sysctl.8;
variable determines how much outstanding write I/O may be
queued to disk controllers system-wide at any given
instance. The default is usually sufficient, but on
machines with many disks, try bumping it up to four or five
megabytes. Setting too high a value
which exceeds the buffer cache's write threshold can lead
to bad clustering performance. Do not set this value
arbitrarily high as higher write values may add latency to
reads occurring at the same time.There are various other buffer cache and
VM page cache related &man.sysctl.8;
values. Modifying these values is not recommended as the
VM system does a good job of
automatically tuning itself.vm.swap_idle_enabledvm.swap_idle_enabledThe vm.swap_idle_enabled
&man.sysctl.8; variable is useful in large multi-user
systems with many active login users and lots of idle
processes. Such systems tend to generate continuous
pressure on free memory reserves. Turning this feature on
and tweaking the swapout hysteresis (in idle seconds) via
vm.swap_idle_threshold1 and
vm.swap_idle_threshold2 depresses the
priority of memory pages associated with idle processes more
quickly then the normal pageout algorithm. This gives a
helping hand to the pageout daemon. Only turn this option
on if needed, because the tradeoff is essentially pre-page
memory sooner rather than later which eats more swap and
disk bandwidth. In a small system this option will have a
determinable effect, but in a large system that is already
doing moderate paging, this option allows the
VM system to stage whole processes into
and out of memory easily.hw.ata.wchw.ata.wcTurning off IDE write caching reduces
write bandwidth to IDE disks, but may
sometimes be necessary due to data consistency issues
introduced by hard drive vendors. The problem is that
some IDE drives lie about when a write
completes. With IDE write caching
turned on, IDE hard drives write data
to disk out of order and will sometimes delay writing some
blocks indefinitely when under heavy disk load. A crash or
power failure may cause serious file system corruption.
Check the default on the system by observing the
hw.ata.wc &man.sysctl.8; variable. If
IDE write caching is turned off, one can
set this read-only variable to
1 in
/boot/loader.conf in order to enable
it at boot time.For more information, refer to &man.ata.4;.SCSI_DELAY
(kern.cam.scsi_delay)kern.cam.scsi_delaykernel optionsSCSI DELAYThe SCSI_DELAY kernel configuration
option may be used to reduce system boot times. The
defaults are fairly high and can be responsible for
15 seconds of delay in the boot process.
Reducing it to 5 seconds usually works
with modern drives. The
kern.cam.scsi_delay boot time tunable
should be used. The tunable and kernel configuration
option accept values in terms of
milliseconds and
notseconds.Soft UpdatesSoft Updates&man.tunefs.8;To fine-tune a file system, use &man.tunefs.8;. This
program has many different options. To toggle Soft Updates
on and off, use:&prompt.root; tunefs -n enable /filesystem
&prompt.root; tunefs -n disable /filesystemA file system cannot be modified with &man.tunefs.8; while
it is mounted. A good time to enable Soft Updates is before
any partitions have been mounted, in single-user mode.Soft Updates is recommended for UFS
file systems as it drastically improves meta-data performance,
mainly file creation and deletion, through the use of a memory
cache. There are two downsides to Soft Updates to be aware
of. First, Soft Updates guarantee file system consistency
in the case of a crash, but could easily be several seconds
or even a minute behind updating the physical disk. If the
system crashes, unwritten data may be lost. Secondly, Soft
Updates delay the freeing of file system blocks. If the
root file system is almost full, performing a major update,
such as make installworld, can cause the
file system to run out of space and the update to fail.More Details About Soft UpdatesSoft UpdatesdetailsMeta-data updates are updates to non-content data like
inodes or directories. There are two traditional approaches
to writing a file system's meta-data back to disk.Historically, the default behavior was to write out
meta-data updates synchronously. If a directory changed,
the system waited until the change was actually written to
disk. The file data buffers (file contents) were passed
through the buffer cache and backed up to disk later on
asynchronously. The advantage of this implementation is
that it operates safely. If there is a failure during an
update, meta-data is always in a consistent state. A
file is either created completely or not at all. If the
data blocks of a file did not find their way out of the
buffer cache onto the disk by the time of the crash,
&man.fsck.8; recognizes this and repairs the file system
by setting the file length to 0.
Additionally, the implementation is clear and simple. The
disadvantage is that meta-data changes are slow. For
example, rm -r touches all the files in a
directory sequentially, but each directory change will be
written synchronously to the disk. This includes updates to
the directory itself, to the inode table, and possibly to
indirect blocks allocated by the file. Similar
considerations apply for unrolling large hierarchies using
tar -x.The second approach is to use asynchronous meta-data
updates. This is the default for a UFS
file system mounted with mount -o async.
Since all meta-data updates are also passed through the
buffer cache, they will be intermixed with the updates of
the file content data. The advantage of this
implementation is there is no need to wait until each
meta-data update has been written to disk, so all operations
which cause huge amounts of meta-data updates work much
faster than in the synchronous case. This implementation
is still clear and simple, so there is a low risk for bugs
creeping into the code. The disadvantage is that there is
no guarantee for a consistent state of the file system.
If there is a failure during an operation that updated
large amounts of meta-data, like a power failure or someone
pressing the reset button, the file system will be left
in an unpredictable state. There is no opportunity to
examine the state of the file system when the system comes
up again as the data blocks of a file could already have
been written to the disk while the updates of the inode
table or the associated directory were not. It is
impossible to implement a &man.fsck.8; which is able to
clean up the resulting chaos because the necessary
information is not available on the disk. If the file
system has been damaged beyond repair, the only choice
is to reformat it and restore from backup.The usual solution for this problem is to implement
dirty region logging, which is also
referred to as journaling.
Meta-data updates are still written synchronously, but only
into a small region of the disk. Later on, they are moved
to their proper location. Because the logging area is a
small, contiguous region on the disk, there are no long
distances for the disk heads to move, even during heavy
operations, so these operations are quicker than synchronous
updates. Additionally, the complexity of the implementation
is limited, so the risk of bugs being present is low. A
disadvantage is that all meta-data is written twice, once
into the logging region and once to the proper location, so
performance pessimization might result. On
the other hand, in case of a crash, all pending meta-data
operations can be either quickly rolled back or completed
from the logging area after the system comes up again,
resulting in a fast file system startup.Kirk McKusick, the developer of Berkeley
FFS, solved this problem with Soft
Updates. All pending meta-data updates are kept in memory
and written out to disk in a sorted sequence
(ordered meta-data updates). This has the
effect that, in case of heavy meta-data operations, later
updates to an item catch the earlier ones
which are still in memory and have not already been written
to disk. All operations are generally performed in memory
before the update is written to disk and the data blocks are
sorted according to their position so that they will not be
on the disk ahead of their meta-data. If the system
crashes, an implicit log rewind causes all
operations which were not written to the disk appear as if
they never happened. A consistent file system state is
maintained that appears to be the one of 30 to 60 seconds
earlier. The algorithm used guarantees that all resources
in use are marked as such in their blocks and inodes.
After a crash, the only resource allocation error that
occurs is that resources are marked as used
which are actually free. &man.fsck.8;
recognizes this situation, and frees the resources that
are no longer used. It is safe to ignore the dirty state
of the file system after a crash by forcibly mounting it
with mount -f. In order to free
resources that may be unused, &man.fsck.8; needs to be run
at a later time. This is the idea behind the
background &man.fsck.8;: at system
startup time, only a snapshot of the
file system is recorded and &man.fsck.8; is run afterwards.
All file systems can then be mounted
dirty, so the system startup proceeds in
multi-user mode. Then, background &man.fsck.8; is
scheduled for all file systems where this is required, to
free resources that may be unused. File systems that do
not use Soft Updates still need the usual foreground
&man.fsck.8;.The advantage is that meta-data operations are nearly
as fast as asynchronous updates and are faster than
logging, which has to write the
meta-data twice. The disadvantages are the complexity of
the code, a higher memory consumption, and some
idiosyncrasies. After a crash, the state of the file
system appears to be somewhat older. In
situations where the standard synchronous approach would
have caused some zero-length files to remain after the
&man.fsck.8;, these files do not exist at all with Soft
Updates because neither the meta-data nor the file contents
have been written to disk. Disk space is not released until
the updates have been written to disk, which may take place
some time after running &man.rm.1;. This may cause problems
when installing large amounts of data on a file system
that does not have enough free space to hold all the files
twice.Tuning Kernel Limitstuningkernel limitsFile/Process Limitskern.maxfileskern.maxfilesThe kern.maxfiles &man.sysctl.8;
variable can be raised or lowered based upon system
requirements. This variable indicates the maximum number
of file descriptors on the system. When the file descriptor
table is full, file: table is full
will show up repeatedly in the system message buffer, which
can be viewed using &man.dmesg.8;.Each open file, socket, or fifo uses one file
descriptor. A large-scale production server may easily
require many thousands of file descriptors, depending on the
kind and number of services running concurrently.In older &os; releases, the default value of
kern.maxfiles is derived from
in the kernel configuration file.
kern.maxfiles grows proportionally to the
value of . When compiling a custom
kernel, consider setting this kernel configuration option
according to the use of the system. From this number, the
kernel is given most of its pre-defined limits. Even though
a production machine may not have 256 concurrent users, the
resources needed may be similar to a high-scale web
server.The read-only &man.sysctl.8; variable
kern.maxusers is automatically sized at
boot based on the amount of memory available in the system,
and may be determined at run-time by inspecting the value
of kern.maxusers. Some systems require
larger or smaller values of
kern.maxusers and values of
64, 128, and
256 are not uncommon. Going above
256 is not recommended unless a huge
number of file descriptors is needed. Many of the tunable
values set to their defaults by
kern.maxusers may be individually
overridden at boot-time or run-time in
/boot/loader.conf. Refer to
&man.loader.conf.5; and
/boot/defaults/loader.conf for more
details and some hints.In older releases, the system will auto-tune
maxusers if it is set to
0.
The auto-tuning algorithm sets
maxusers equal to the amount of
memory in the system, with a minimum of
32, and a maximum of
384.. When
setting this option, set maxusers to
at least 4, especially if the system
runs &xorg; or is used to
compile software. The most important table set by
maxusers is the maximum number of
processes, which is set to
20 + 16 * maxusers. If
maxusers is set to 1,
there can only be
36 simultaneous processes, including
the 18 or so that the system starts up
at boot time and the 15 or so used by
&xorg;. Even a simple task like
reading a manual page will start up nine processes to
filter, decompress, and view it. Setting
maxusers to 64 allows
up to 1044 simultaneous processes, which
should be enough for nearly all uses. If, however, the
proc table full error is displayed
when trying to start another program, or a server is
running with a large number of simultaneous users, increase
the number and rebuild.maxusers does
not limit the number of users which
can log into the machine. It instead sets various table
sizes to reasonable values considering the maximum number
of users on the system and how many processes each user
will be running.kern.ipc.soacceptqueuekern.ipc.soacceptqueueThe kern.ipc.soacceptqueue
&man.sysctl.8; variable limits the size of the listen queue
for accepting new TCP connections. The
default value of 128 is typically too low
for robust handling of new connections on a heavily loaded
web server. For such environments, it is recommended to
increase this value to 1024 or higher. A
service such as &man.sendmail.8;, or
Apache may itself limit the
listen queue size, but will often have a directive in its
configuration file to adjust the queue size. Large listen
queues do a better job of avoiding Denial of Service
(DoS) attacks.Network LimitsThe NMBCLUSTERS kernel configuration
option dictates the amount of network Mbufs available to the
system. A heavily-trafficked server with a low number of
Mbufs will hinder performance. Each cluster represents
approximately 2 K of memory, so a value of
1024 represents 2
megabytes of kernel memory reserved for network buffers. A
simple calculation can be done to figure out how many are
needed. A web server which maxes out at
1000 simultaneous connections where each
connection uses a 6 K receive and 16 K send buffer,
requires approximately 32 MB worth of network buffers
to cover the web server. A good rule of thumb is to multiply
by 2, so
2x32 MB / 2 KB =
64 MB / 2 kB =
32768. Values between
4096 and 32768 are
recommended for machines with greater amounts of memory.
Never specify an arbitrarily high value for this parameter
as it could lead to a boot time crash. To observe network
cluster usage, use with
&man.netstat.1;.The kern.ipc.nmbclusters loader tunable
should be used to tune this at boot time. Only older versions
of &os; will require the use of the
NMBCLUSTERS kernel &man.config.8;
option.For busy servers that make extensive use of the
&man.sendfile.2; system call, it may be necessary to increase
the number of &man.sendfile.2; buffers via the
NSFBUFS kernel configuration option or by
setting its value in /boot/loader.conf
(see &man.loader.8; for details). A common indicator that
this parameter needs to be adjusted is when processes are seen
in the sfbufa state. The &man.sysctl.8;
variable kern.ipc.nsfbufs is read-only.
This parameter nominally scales with
kern.maxusers, however it may be necessary
to tune accordingly.Even though a socket has been marked as non-blocking,
calling &man.sendfile.2; on the non-blocking socket may
result in the &man.sendfile.2; call blocking until enough
struct sf_buf's are made
available.net.inet.ip.portrange.*net.inet.ip.portrange.*The net.inet.ip.portrange.*
&man.sysctl.8; variables control the port number ranges
automatically bound to TCP and
UDP sockets. There are three ranges: a
low range, a default range, and a high range. Most network
programs use the default range which is controlled by
net.inet.ip.portrange.first and
net.inet.ip.portrange.last, which default
to 1024 and 5000,
respectively. Bound port ranges are used for outgoing
connections and it is possible to run the system out of
ports under certain circumstances. This most commonly
occurs when running a heavily loaded web proxy. The port
range is not an issue when running a server which handles
mainly incoming connections, such as a web server, or has
a limited number of outgoing connections, such as a mail
relay. For situations where there is a shortage of ports,
it is recommended to increase
net.inet.ip.portrange.last modestly. A
value of 10000, 20000
or 30000 may be reasonable. Consider
firewall effects when changing the port range. Some
firewalls may block large ranges of ports, usually
low-numbered ports, and expect systems to use higher ranges
of ports for outgoing connections. For this reason, it
is not recommended that the value of
net.inet.ip.portrange.first be
lowered.TCP Bandwidth Delay ProductTCP Bandwidth Delay Product
Limitingnet.inet.tcp.inflight.enableTCP bandwidth delay product limiting
can be enabled by setting the
net.inet.tcp.inflight.enable
&man.sysctl.8; variable to 1. This
instructs the system to attempt to calculate the bandwidth
delay product for each connection and limit the amount of
data queued to the network to just the amount required to
maintain optimum throughput.This feature is useful when serving data over modems,
Gigabit Ethernet, high speed WAN links,
or any other link with a high bandwidth delay product,
especially when also using window scaling or when a large
send window has been configured. When enabling this option,
also set net.inet.tcp.inflight.debug to
0 to disable debugging. For production
use, setting net.inet.tcp.inflight.min
to at least 6144 may be beneficial.
Setting high minimums may effectively disable bandwidth
limiting, depending on the link. The limiting feature
reduces the amount of data built up in intermediate route
and switch packet queues and reduces the amount of data
built up in the local host's interface queue. With fewer
queued packets, interactive connections, especially over
slow modems, will operate with lower
Round Trip Times. This feature only
effects server side data transmission such as uploading.
It has no effect on data reception or downloading.Adjusting net.inet.tcp.inflight.stab
is not recommended. This parameter
defaults to 20, representing 2 maximal
packets added to the bandwidth delay product window
calculation. The additional window is required to stabilize
the algorithm and improve responsiveness to changing
conditions, but it can also result in higher &man.ping.8;
times over slow links, though still much lower than without
the inflight algorithm. In such cases, try reducing this
parameter to 15, 10,
or 5 and reducing
net.inet.tcp.inflight.min to a value such
as 3500 to get the desired effect.
Reducing these parameters should be done as a last resort
only.Virtual Memorykern.maxvnodesA vnode is the internal representation of a file or
directory. Increasing the number of vnodes available to
the operating system reduces disk I/O. Normally, this is
handled by the operating system and does not need to be
changed. In some cases where disk I/O is a bottleneck and
the system is running out of vnodes, this setting needs
to be increased. The amount of inactive and free
RAM will need to be taken into
account.To see the current number of vnodes in use:&prompt.root; sysctl vfs.numvnodes
vfs.numvnodes: 91349To see the maximum vnodes:&prompt.root; sysctl kern.maxvnodes
kern.maxvnodes: 100000If the current vnode usage is near the maximum, try
increasing kern.maxvnodes by a value of
1000. Keep an eye on the number of
vfs.numvnodes. If it climbs up to the
maximum again, kern.maxvnodes will need
to be increased further. Otherwise, a shift in memory
usage as reported by &man.top.1; should be visible and
more memory should be active.Adding Swap SpaceSometimes a system requires more swap space. This section
describes two methods to increase swap space: adding swap to an
existing partition or new hard drive, and creating a swap file
on an existing partition.For information on how to encrypt swap space, which options
exist, and why it should be done, refer to .Swap on a New Hard Drive or Existing PartitionAdding a new hard drive for swap gives better performance
than using a partition on an existing drive. Setting up
partitions and hard drives is explained in while discusses partition layouts
and swap partition size considerations.Use swapon to add a swap partition to
the system. For example:&prompt.root; swapon /dev/ada1s1bIt is possible to use any partition not currently
mounted, even if it already contains data. Using
swapon on a partition that contains data
will overwrite and destroy that data. Make sure that the
partition to be added as swap is really the intended
partition before running swapon.To automatically add this swap partition on boot, add an
entry to /etc/fstab:/dev/ada1s1b none swap sw 0 0See &man.fstab.5; for an explanation of the entries in
/etc/fstab. More information about
swapon can be found in
&man.swapon.8;.Creating a Swap FileThese examples create a 64M swap file called
/usr/swap0 instead of using a
partition.Using swap files requires that the module needed by
&man.md.4; has either been built into the kernel or has been
loaded before swap is enabled. See
for information about building
a custom kernel.Creating a Swap File on
&os; 10.X and LaterCreate the swap file:&prompt.root; dd if=/dev/zero of=/usr/swap0 bs=1m count=64Set the proper permissions on the new file:&prompt.root; chmod 0600 /usr/swap0Inform the system about the swap file by adding a
line to /etc/fstab:md99 none swap sw,file=/usr/swap0,late 0 0The &man.md.4; device md99 is
used, leaving lower device numbers available for
interactive use.Swap space will be added on system startup. To add
swap space immediately, use &man.swapon.8;:&prompt.root; swapon -aLCreating a Swap File on
&os; 9.X and EarlierCreate the swap file,
/usr/swap0:&prompt.root; dd if=/dev/zero of=/usr/swap0 bs=1m count=64Set the proper permissions on
/usr/swap0:&prompt.root; chmod 0600 /usr/swap0Enable the swap file in
/etc/rc.conf:swapfile="/usr/swap0" # Set to name of swap fileSwap space will be added on system startup. To
enable the swap file immediately, specify a free memory
device. Refer to for
more information about memory devices.&prompt.root; mdconfig -a -t vnode -f /usr/swap0 -u 0 && swapon /dev/md0Power and Resource ManagementHitenPandyaWritten by TomRhodesIt is important to utilize hardware resources in an
efficient manner. Power and resource management allows the
operating system to monitor system limits and to possibly
provide an alert if the system temperature increases
unexpectedly. An early specification for providing power
management was the Advanced Power Management
(APM) facility. APM
controls the power usage of a system based on its activity.
However, it was difficult and inflexible for operating systems
to manage the power usage and thermal properties of a system.
The hardware was managed by the BIOS and the
user had limited configurability and visibility into the power
management settings. The APM
BIOS is supplied by the vendor and is
specific to the hardware platform. An APM
driver in the operating system mediates access to the
APM Software Interface, which allows
management of power levels.There are four major problems in APM.
First, power management is done by the vendor-specific
BIOS, separate from the operating system.
For example, the user can set idle-time values for a hard drive
in the APM BIOS so that,
when exceeded, the BIOS spins down the hard
drive without the consent of the operating system. Second, the
APM logic is embedded in the
BIOS, and it operates outside the scope of
the operating system. This means that users can only fix
problems in the APM
BIOS by flashing a new one into the
ROM, which is a dangerous procedure with the
potential to leave the system in an unrecoverable state if it
fails. Third, APM is a vendor-specific
technology, meaning that there is a lot of duplication of
efforts and bugs found in one vendor's BIOS
may not be solved in others. Lastly, the APM
BIOS did not have enough room to implement a
sophisticated power policy or one that can adapt well to the
purpose of the machine.The Plug and Play BIOS
(PNPBIOS) was unreliable in many situations.
PNPBIOS is 16-bit technology, so the
operating system has to use 16-bit emulation in order to
interface with PNPBIOS methods. &os;
provides an APM driver as
APM should still be used for systems
manufactured at or before the year 2000. The driver is
documented in &man.apm.4;.ACPIAPMThe successor to APM is the Advanced
Configuration and Power Interface (ACPI).
ACPI is a standard written by an alliance of
vendors to provide an interface for hardware resources and power
management. It is a key element in Operating
System-directed configuration and Power Management
as it provides more control and flexibility to the operating
system.This chapter demonstrates how to configure
ACPI on &os;. It then offers some tips on
how to debug ACPI and how to submit a problem
report containing debugging information so that developers can
diagnosis and fix ACPI issues.Configuring ACPIIn &os; the &man.acpi.4; driver is loaded by default at
system boot and should not be compiled
into the kernel. This driver cannot be unloaded after boot
because the system bus uses it for various hardware
interactions. However, if the system is experiencing
problems, ACPI can be disabled altogether
by rebooting after setting
hint.acpi.0.disabled="1" in
/boot/loader.conf or by setting this
variable at the loader prompt, as described in .ACPI and APM
cannot coexist and should be used separately. The last one
to load will terminate if the driver notices the other is
running.ACPI can be used to put the system into
a sleep mode with acpiconf, the
flag, and a number from
1 to 5. Most users only
need 1 (quick suspend to
RAM) or 3 (suspend to
RAM). Option 5 performs
a soft-off which is the same as running
halt -p.Other options are available using
sysctl. Refer to &man.acpi.4; and
&man.acpiconf.8; for more information.Common ProblemsACPIACPI is present in all modern computers
that conform to the ia32 (x86), ia64 (Itanium), and amd64
(AMD) architectures. The full standard has
many features including CPU performance
management, power planes control, thermal zones, various
battery systems, embedded controllers, and bus enumeration.
Most systems implement less than the full standard. For
instance, a desktop system usually only implements bus
enumeration while a laptop might have cooling and battery
management support as well. Laptops also have suspend and
resume, with their own associated complexity.An ACPI-compliant system has various
components. The BIOS and chipset vendors
provide various fixed tables, such as FADT,
in memory that specify things like the APIC
map (used for SMP), config registers, and
simple configuration values. Additionally, a bytecode table,
the Differentiated System Description Table
DSDT, specifies a tree-like name space of
devices and methods.The ACPI driver must parse the fixed
tables, implement an interpreter for the bytecode, and modify
device drivers and the kernel to accept information from the
ACPI subsystem. For &os;, &intel; has
provided an interpreter (ACPI-CA) that is
shared with &linux; and NetBSD. The path to the
ACPI-CA source code is
src/sys/contrib/dev/acpica. The glue
code that allows ACPI-CA to work on &os; is
in src/sys/dev/acpica/Osd. Finally,
drivers that implement various ACPI devices
are found in src/sys/dev/acpica.ACPIproblemsFor ACPI to work correctly, all the
parts have to work correctly. Here are some common problems,
in order of frequency of appearance, and some possible
workarounds or fixes. If a fix does not resolve the issue,
refer to for instructions
on how to submit a bug report.Mouse IssuesIn some cases, resuming from a suspend operation will
cause the mouse to fail. A known work around is to add
hint.psm.0.flags="0x3000" to
/boot/loader.conf.Suspend/ResumeACPI has three suspend to
RAM (STR) states,
S1-S3, and one suspend
to disk state (STD), called
S4. STD can be
implemented in two separate ways. The
S4BIOS is a
BIOS-assisted suspend to disk and
S4OS is implemented
entirely by the operating system. The normal state the
system is in when plugged in but not powered up is
soft off (S5).Use sysctl hw.acpi to check for the
suspend-related items. These example results are from a
Thinkpad:hw.acpi.supported_sleep_state: S3 S4 S5
hw.acpi.s4bios: 0Use acpiconf -s to test
S3, S4, and
S5. An of one
(1) indicates
S4BIOS support instead
of S4 operating system support.When testing suspend/resume, start with
S1, if supported. This state is most
likely to work since it does not require much driver
support. No one has implemented S2,
which is similar to S1. Next, try
S3. This is the deepest
STR state and requires a lot of driver
support to properly reinitialize the hardware.A common problem with suspend/resume is that many device
drivers do not save, restore, or reinitialize their
firmware, registers, or device memory properly. As a first
attempt at debugging the problem, try:&prompt.root; sysctl debug.bootverbose=1
&prompt.root; sysctl debug.acpi.suspend_bounce=1
&prompt.root; acpiconf -s 3This test emulates the suspend/resume cycle of all
device drivers without actually going into
S3 state. In some cases, problems such
as losing firmware state, device watchdog time out, and
retrying forever, can be captured with this method. Note
that the system will not really enter S3
state, which means devices may not lose power, and many
will work fine even if suspend/resume methods are totally
missing, unlike real S3 state.Harder cases require additional hardware, such as a
serial port and cable for debugging through a serial
console, a Firewire port and cable for using &man.dcons.4;,
and kernel debugging skills.To help isolate the problem, unload as many drivers as
possible. If it works, narrow down which driver is the
problem by loading drivers until it fails again. Typically,
binary drivers like nvidia.ko, display
drivers, and USB will have the most
problems while Ethernet interfaces usually work fine. If
drivers can be properly loaded and unloaded, automate this
by putting the appropriate commands in
/etc/rc.suspend and
/etc/rc.resume. Try setting
to 1
if the display is messed up after resume. Try setting
longer or shorter values for
to see if that
helps.Try loading a recent &linux; distribution to see if
suspend/resume works on the same hardware. If it works on
&linux;, it is likely a &os; driver problem. Narrowing down
which driver causes the problem will assist developers in
fixing the problem. Since the ACPI
maintainers rarely maintain other drivers, such as sound
or ATA, any driver problems should also
be posted to the &a.current.name; list and mailed to the
driver maintainer. Advanced users can include debugging
&man.printf.3;s in a problematic driver to track down where
in its resume function it hangs.Finally, try disabling ACPI and
enabling APM instead. If suspend/resume
works with APM, stick with
APM, especially on older hardware
(pre-2000). It took vendors a while to get
ACPI support correct and older hardware
is more likely to have BIOS problems with
ACPI.System HangsMost system hangs are a result of lost interrupts or an
interrupt storm. Chipsets may have problems based on boot,
how the BIOS configures interrupts before
correctness of the APIC
(MADT) table, and routing of the System
Control Interrupt (SCI).interrupt stormsInterrupt storms can be distinguished from lost
interrupts by checking the output of
vmstat -i and looking at the line that
has acpi0. If the counter is increasing
at more than a couple per second, there is an interrupt
storm. If the system appears hung, try breaking to
DDB (CTRLALTESC on console) and type
show interrupts.APICdisablingWhen dealing with interrupt problems, try disabling
APIC support with
hint.apic.0.disabled="1" in
/boot/loader.conf.PanicsPanics are relatively rare for ACPI
and are the top priority to be fixed. The first step is to
isolate the steps to reproduce the panic, if possible, and
get a backtrace. Follow the advice for enabling
options DDB and setting up a serial
console in or setting
up a dump partition. To get a backtrace in
DDB, use tr. When
handwriting the backtrace, get at least the last five and
the top five lines in the trace.Then, try to isolate the problem by booting with
ACPI disabled. If that works, isolate
the ACPI subsystem by using various
values of . See
&man.acpi.4; for some examples.System Powers Up After Suspend or ShutdownFirst, try setting
hw.acpi.disable_on_poweroff="0" in
/boot/loader.conf. This keeps
ACPI from disabling various events during
the shutdown process. Some systems need this value set to
1 (the default) for the same reason.
This usually fixes the problem of a system powering up
spontaneously after a suspend or poweroff.BIOS Contains Buggy BytecodeACPIASLSome BIOS vendors provide incorrect
or buggy bytecode. This is usually manifested by kernel
console messages like this:ACPI-1287: *** Error: Method execution failed [\\_SB_.PCI0.LPC0.FIGD._STA] \\
(Node 0xc3f6d160), AE_NOT_FOUNDOften, these problems may be resolved by updating the
BIOS to the latest revision. Most
console messages are harmless, but if there are other
problems, like the battery status is not working, these
messages are a good place to start looking for
problems.Overriding the Default AMLThe BIOS bytecode, known as
ACPI Machine Language
(AML), is compiled from a source language
called ACPI Source Language
(ASL). The AML is
found in the table known as the Differentiated System
Description Table (DSDT).ACPIASLThe goal of &os; is for everyone to have working
ACPI without any user intervention.
Workarounds are still being developed for common mistakes made
by BIOS vendors. The µsoft;
interpreter (acpi.sys and
acpiec.sys) does not strictly check for
adherence to the standard, and thus many
BIOS vendors who only test
ACPI under &windows; never fix their
ASL. &os; developers continue to identify
and document which non-standard behavior is allowed by
µsoft;'s interpreter and replicate it so that &os; can
work without forcing users to fix the
ASL.To help identify buggy behavior and possibly fix it
manually, a copy can be made of the system's
ASL. To copy the system's
ASL to a specified file name, use
acpidump with , to show
the contents of the fixed tables, and , to
disassemble the AML:&prompt.root; acpidump -td > my.aslSome AML versions assume the user is
running &windows;. To override this, set
hw.acpi.osname="Windows
2009" in
/boot/loader.conf, using the most recent
&windows; version listed in the ASL.Other workarounds may require my.asl
to be customized. If this file is edited, compile the new
ASL using the following command. Warnings
can usually be ignored, but errors are bugs that will usually
prevent ACPI from working correctly.&prompt.root; iasl -f my.aslIncluding forces creation of the
AML, even if there are errors during
compilation. Some errors, such as missing return statements,
are automatically worked around by the &os;
interpreter.The default output filename for iasl is
DSDT.aml. Load this file instead of the
BIOS's buggy copy, which is still present
in flash memory, by editing
/boot/loader.conf as follows:acpi_dsdt_load="YES"
acpi_dsdt_name="/boot/DSDT.aml"Be sure to copy DSDT.aml to
/boot, then reboot the system. If this
fixes the problem, send a &man.diff.1; of the old and new
ASL to &a.acpi.name; so that developers can
work around the buggy behavior in
acpica.Getting and Submitting Debugging InfoNateLawsonWritten by PeterSchultzWith contributions from TomRhodesACPIproblemsACPIdebuggingThe ACPI driver has a flexible
debugging facility. A set of subsystems and the level of
verbosity can be specified. The subsystems to debug are
specified as layers and are broken down into components
(ACPI_ALL_COMPONENTS) and
ACPI hardware support
(ACPI_ALL_DRIVERS). The verbosity of
debugging output is specified as the level and ranges from
just report errors (ACPI_LV_ERROR) to
everything (ACPI_LV_VERBOSE). The level is
a bitmask so multiple options can be set at once, separated by
spaces. In practice, a serial console should be used to log
the output so it is not lost as the console message buffer
flushes. A full list of the individual layers and levels is
found in &man.acpi.4;.Debugging output is not enabled by default. To enable it,
add options ACPI_DEBUG to the custom kernel
configuration file if ACPI is compiled into
the kernel. Add ACPI_DEBUG=1 to
/etc/make.conf to enable it globally. If
a module is used instead of a custom kernel, recompile just
the acpi.ko module as follows:&prompt.root; cd /sys/modules/acpi/acpi && make clean && make ACPI_DEBUG=1Copy the compiled acpi.ko to
/boot/kernel and add the desired level
and layer to /boot/loader.conf. The
entries in this example enable debug messages for all
ACPI components and hardware drivers and
output error messages at the least verbose level:debug.acpi.layer="ACPI_ALL_COMPONENTS ACPI_ALL_DRIVERS"
debug.acpi.level="ACPI_LV_ERROR"If the required information is triggered by a specific
event, such as a suspend and then resume, do not modify
/boot/loader.conf. Instead, use
sysctl to specify the layer and level after
booting and preparing the system for the specific event. The
variables which can be set using sysctl are
named the same as the tunables in
/boot/loader.conf.ACPIproblemsOnce the debugging information is gathered, it can be sent
to &a.acpi.name; so that it can be used by the &os;
ACPI maintainers to identify the root cause
of the problem and to develop a solution.Before submitting debugging information to this mailing
list, ensure the latest BIOS version is
installed and, if available, the embedded controller
firmware version.When submitting a problem report, include the following
information:Description of the buggy behavior, including system
type, model, and anything that causes the bug to appear.
Note as accurately as possible when the bug began
occurring if it is new.The output of dmesg after running
boot -v, including any error messages
generated by the bug.The dmesg output from boot
-v with ACPI disabled,
if disabling ACPI helps to fix the
problem.Output from sysctl hw.acpi. This
lists which features the system offers.The URL to a pasted version of the
system's ASL. Do
not send the ASL
directly to the list as it can be very large. Generate a
copy of the ASL by running this
command:&prompt.root; acpidump -dt > name-system.aslSubstitute the login name for
name and manufacturer/model for
system. For example, use
njl-FooCo6000.asl.Most &os; developers watch the &a.current;, but one should
submit problems to &a.acpi.name; to be sure it is seen. Be
patient when waiting for a response. If the bug is not
immediately apparent, submit a PR using
&man.send-pr.1;. When entering a PR,
include the same information as requested above. This helps
developers to track the problem and resolve it. Do not send a
PR without emailing &a.acpi.name; first as
it is likely that the problem has been reported before.ReferencesMore information about ACPI may be
found in the following locations:The &os; ACPI Mailing List Archives
(http://lists.freebsd.org/pipermail/freebsd-acpi/)The ACPI 2.0 Specification (http://acpi.info/spec.htm)&man.acpi.4;, &man.acpi.thermal.4;, &man.acpidump.8;,
&man.iasl.8;, and &man.acpidb.8;
Index: head/en_US.ISO8859-1/books/handbook/disks/chapter.xml
===================================================================
--- head/en_US.ISO8859-1/books/handbook/disks/chapter.xml (revision 50807)
+++ head/en_US.ISO8859-1/books/handbook/disks/chapter.xml (revision 50808)
@@ -1,3806 +1,3806 @@
StorageSynopsisThis chapter covers the use of disks and storage media in
&os;. This includes SCSI and
IDE disks, CD and
DVD media, memory-backed disks, and
USB storage devices.After reading this chapter, you will know:How to add additional hard disks to a &os;
system.How to grow the size of a disk's partition on
&os;.How to configure &os; to use USB
storage devices.How to use CD and
DVD media on a &os; system.How to use the backup programs available under
&os;.How to set up memory disks.What file system snapshots are and how to use them
efficiently.How to use quotas to limit disk space usage.How to encrypt disks and swap to secure them against
attackers.How to configure a highly available storage
network.Before reading this chapter, you should:Know how to configure and
install a new &os; kernel.Adding DisksDavidO'BrienOriginally contributed by disksaddingThis section describes how to add a new
SATA disk to a machine that currently only
has a single drive. First, turn off the computer and install
the drive in the computer following the instructions of the
computer, controller, and drive manufacturers. Reboot the
system and become
root.Inspect /var/run/dmesg.boot to ensure
the new disk was found. In this example, the newly added
SATA drive will appear as
ada1.partitionsgpartFor this example, a single large partition will be created
on the new disk. The
GPT partitioning scheme will be
used in preference to the older and less versatile
MBR scheme.If the disk to be added is not blank, old partition
information can be removed with
gpart delete. See &man.gpart.8; for
details.The partition scheme is created, and then a single partition
is added. To improve performance on newer disks with larger
hardware block sizes, the partition is aligned to one megabyte
boundaries:&prompt.root; gpart create -s GPT ada1
&prompt.root; gpart add -t freebsd-ufs -a 1M ada1Depending on use, several smaller partitions may be desired.
See &man.gpart.8; for options to create partitions smaller than
a whole disk.The disk partition information can be viewed with
gpart show:&prompt.user; gpart show ada1
=> 34 1465146988 ada1 GPT (699G)
34 2014 - free - (1.0M)
2048 1465143296 1 freebsd-ufs (699G)
1465145344 1678 - free - (839K)A file system is created in the new partition on the new disk:&prompt.root; newfs -U /dev/ada1p1An empty directory is created as a
mountpoint, a location for mounting the new
disk in the original disk's file system:&prompt.root; mkdir /newdiskFinally, an entry is added to
/etc/fstab so the new disk will be mounted
automatically at startup:/dev/ada1p1 /newdisk ufs rw 2 2The new disk can be mounted manually, without restarting the
system:&prompt.root; mount /newdiskResizing and Growing DisksAllanJudeOriginally contributed by disksresizingA disk's capacity can increase without any changes to the
data already present. This happens commonly with virtual
machines, when the virtual disk turns out to be too small and is
enlarged. Sometimes a disk image is written to a
USB memory stick, but does not use the full
capacity. Here we describe how to resize or
grow disk contents to take advantage of
increased capacity.Determine the device name of the disk to be resized by
inspecting /var/run/dmesg.boot. In this
example, there is only one SATA disk in the
system, so the drive will appear as
ada0.partitionsgpartList the partitions on the disk to see the current
configuration:&prompt.root; gpart show ada0
=> 34 83886013 ada0 GPT (48G) [CORRUPT]
34 128 1 freebsd-boot (64k)
162 79691648 2 freebsd-ufs (38G)
79691810 4194236 3 freebsd-swap (2G)
83886046 1 - free - (512B)If the disk was formatted with the
GPT partitioning scheme, it may show
as corrupted because the GPT
backup partition table is no longer at the end of the
drive. Fix the backup
partition table with
gpart:&prompt.root; gpart recover ada0
ada0 recoveredNow the additional space on the disk is available for
use by a new partition, or an existing partition can be
expanded:&prompt.root; gpart show ada0
=> 34 102399933 ada0 GPT (48G)
34 128 1 freebsd-boot (64k)
162 79691648 2 freebsd-ufs (38G)
79691810 4194236 3 freebsd-swap (2G)
83886046 18513921 - free - (8.8G)Partitions can only be resized into contiguous free space.
Here, the last partition on the disk is the swap partition, but
the second partition is the one that needs to be resized. Swap
partitions only contain temporary data, so it can safely be
unmounted, deleted, and then recreated after resizing other
partitions.&prompt.root; swapoff /dev/ada0p3
&prompt.root; gpart delete -i 3ada0
ada0p3 deleted
&prompt.root; gpart show ada0
=> 34 102399933 ada0 GPT (48G)
34 128 1 freebsd-boot (64k)
162 79691648 2 freebsd-ufs (38G)
79691810 22708157 - free - (10G)There is risk of data loss when modifying the partition
table of a mounted file system. It is best to perform the
following steps on an unmounted file system while running from
a live CD-ROM or USB
device. However, if absolutely necessary, a mounted file
system can be resized after disabling GEOM safety
features:&prompt.root; sysctl kern.geom.debugflags=16Resize the partition, leaving room to recreate a swap
partition of the desired size. This only modifies the size of
the partition. The file system in the partition will be
expanded in a separate step.&prompt.root; gpart resize -i 2 -a 4k -s 47Gada0
ada0p2 resized
&prompt.root; gpart show ada0
=> 34 102399933 ada0 GPT (48G)
34 128 1 freebsd-boot (64k)
162 98566144 2 freebsd-ufs (47G)
98566306 3833661 - free - (1.8G)Recreate the swap partition:&prompt.root; gpart add -t freebsd-swap -a 4k ada0
ada0p3 added
&prompt.root; gpart show ada0
=> 34 102399933 ada0 GPT (48G)
34 128 1 freebsd-boot (64k)
162 98566144 2 freebsd-ufs (47G)
98566306 3833661 3 freebsd-swap (1.8G)
&prompt.root; swapon /dev/ada0p3Grow the UFS file system to use the new
capacity of the resized partition:Growing a live UFS file system is only
possible in &os; 10.0-RELEASE and later. For earlier
versions, the file system must not be mounted.&prompt.root; growfs /dev/ada0p2
Device is mounted read-write; resizing will result in temporary write suspension for /.
It's strongly recommended to make a backup before growing the file system.
OK to grow file system on /dev/ada0p2, mounted on /, from 38GB to 47GB? [Yes/No] Yes
super-block backups (for fsck -b #) at:
80781312, 82063552, 83345792, 84628032, 85910272, 87192512, 88474752,
89756992, 91039232, 92321472, 93603712, 94885952, 96168192, 97450432Both the partition and the file system on it have now been
resized to use the newly-available disk space.USB Storage DevicesMarcFonvieilleContributed by USBdisksMany external storage solutions, such as hard drives,
USB thumbdrives, and CD
and DVD burners, use the Universal Serial Bus
(USB). &os; provides support for
USB 1.x, 2.0, and 3.0 devices.USB 3.0 support is not compatible with
some hardware, including Haswell (Lynx point) chipsets. If
&os; boots with a failed with error 19
message, disable xHCI/USB3 in the system
BIOS.Support for USB storage devices is built
into the GENERIC kernel. For a custom
kernel, be sure that the following lines are present in the
kernel configuration file:device scbus # SCSI bus (required for ATA/SCSI)
device da # Direct Access (disks)
device pass # Passthrough device (direct ATA/SCSI access)
device uhci # provides USB 1.x support
device ohci # provides USB 1.x support
device ehci # provides USB 2.0 support
device xhci # provides USB 3.0 support
device usb # USB Bus (required)
device umass # Disks/Mass storage - Requires scbus and da
device cd # needed for CD and DVD burners&os; uses the &man.umass.4; driver which uses the
SCSI subsystem to access
USB storage devices. Since any
USB device will be seen as a
SCSI device by the system, if the
USB device is a CD or
DVD burner, do not
include in a custom kernel
configuration file.The rest of this section demonstrates how to verify that a
USB storage device is recognized by &os; and
how to configure the device so that it can be used.Device ConfigurationTo test the USB configuration, plug in
the USB device. Use
dmesg to confirm that the drive appears in
the system message buffer. It should look something like
this:umass0: <STECH Simple Drive, class 0/0, rev 2.00/1.04, addr 3> on usbus0
umass0: SCSI over Bulk-Only; quirks = 0x0100
umass0:4:0:-1: Attached to scbus4
da0 at umass-sim0 bus 0 scbus4 target 0 lun 0
da0: <STECH Simple Drive 1.04> Fixed Direct Access SCSI-4 device
da0: Serial Number WD-WXE508CAN263
da0: 40.000MB/s transfers
da0: 152627MB (312581808 512 byte sectors: 255H 63S/T 19457C)
da0: quirks=0x2<NO_6_BYTE>The brand, device node (da0), speed,
and size will differ according to the device.Since the USB device is seen as a
SCSI one, camcontrol can
be used to list the USB storage devices
attached to the system:&prompt.root; camcontrol devlist
<STECH Simple Drive 1.04> at scbus4 target 0 lun 0 (pass3,da0)Alternately, usbconfig can be used to
list the device. Refer to &man.usbconfig.8; for more
information about this command.&prompt.root; usbconfig
ugen0.3: <Simple Drive STECH> at usbus0, cfg=0 md=HOST spd=HIGH (480Mbps) pwr=ON (2mA)If the device has not been formatted, refer to for instructions on how to format
and create partitions on the USB drive. If
the drive comes with a file system, it can be mounted by
root using the
instructions in .Allowing untrusted users to mount arbitrary media, by
enabling vfs.usermount as described
below, should not be considered safe from a security point
of view. Most file systems were not built to safeguard
against malicious devices.To make the device mountable as a normal user, one
solution is to make all users of the device a member of the
operator group
using &man.pw.8;. Next, ensure that operator is able to read and
write the device by adding these lines to
/etc/devfs.rules:[localrules=5]
add path 'da*' mode 0660 group operatorIf internal SCSI disks are also
installed in the system, change the second line as
follows:add path 'da[3-9]*' mode 0660 group operatorThis will exclude the first three
SCSI disks (da0 to
da2)from belonging to the operator group. Replace
3 with the number of internal
SCSI disks. Refer to &man.devfs.rules.5;
for more information about this file.Next, enable the ruleset in
/etc/rc.conf:devfs_system_ruleset="localrules"Then, instruct the system to allow regular users to mount
file systems by adding the following line to
/etc/sysctl.conf:vfs.usermount=1Since this only takes effect after the next reboot, use
sysctl to set this variable now:&prompt.root; sysctl vfs.usermount=1
vfs.usermount: 0 -> 1The final step is to create a directory where the file
system is to be mounted. This directory needs to be owned by
the user that is to mount the file system. One way to do that
is for root to
create a subdirectory owned by that user as /mnt/username.
In the following example, replace
username with the login name of the
user and usergroup with the user's
primary group:&prompt.root; mkdir /mnt/username
&prompt.root; chown username:usergroup /mnt/usernameSuppose a USB thumbdrive is plugged in,
and a device /dev/da0s1 appears. If the
device is formatted with a FAT file system,
the user can mount it using:&prompt.user; mount -t msdosfs -o -m=644,-M=755 /dev/da0s1 /mnt/usernameBefore the device can be unplugged, it
must be unmounted first:&prompt.user; umount /mnt/usernameAfter device removal, the system message buffer will show
messages similar to the following:umass0: at uhub3, port 2, addr 3 (disconnected)
da0 at umass-sim0 bus 0 scbus4 target 0 lun 0
da0: <STECH Simple Drive 1.04> s/n WD-WXE508CAN263 detached
(da0:umass-sim0:0:0:0): Periph destroyedAutomounting Removable Media&man.autofs.5; supports automatic mounting of
removable media starting with &os; 10.2-RELEASE.USB devices can be automatically
mounted by uncommenting this line in
/etc/auto_master:/media -media -nosuidThen add these lines to
/etc/devd.conf:notify 100 {
match "system" "GEOM";
match "subsystem" "DEV";
action "/usr/sbin/automount -c";
};Reload the configuration if &man.autofs.5;
and &man.devd.8; are already running:&prompt.root; service automount reload
&prompt.root; service devd restart&man.autofs.5; can be set to start at boot by adding this
line to /etc/rc.conf:autofs_enable="YES"&man.autofs.5; requires &man.devd.8; to be enabled, as it
is by default.Start the services immediately with:&prompt.root; service automount start
&prompt.root; service automountd start
&prompt.root; service autounmountd start
&prompt.root; service devd startEach file system that can be automatically mounted appears
as a directory in /media/. The directory
is named after the file system label. If the label is
missing, the directory is named after the device node.The file system is transparently mounted on the first
access, and unmounted after a period of inactivity.
Automounted drives can also be unmounted manually:&prompt.root; automount -fuThis mechanism is typically used for memory cards and
USB memory sticks. It can be used with
any block device, including optical drives or
iSCSI LUNs.USB Mass Storage TargetThe &man.cfumass.4; driver is a USB
device mode driver first available in &os; 12.0.When running on USB
OTG-compliant hardware like that built into
many embedded boards, the &os; USB stack
can run in device mode. Device mode
makes it possible for the computer to present itself as
different kinds of USB device classes,
including serial ports, network adapters, and mass storage. A
USB host like a laptop or desktop computer
is able to access them just like physical
USB devices.The &man.usb.template.4; kernel module allows the
USB stack to switch between host-side and
device-side automatically, depending on what is connected to
the USB port. Connecting a
USB device like a memory stick to the
USB OTG port causes &os;
to switch to host mode. Connecting a USB
host like a computer causes &os; to switch to device
mode.What &os; presents to the USB host
depends on the hw.usb.template sysctl. See
&man.usb.template.4; for the list of available values. Note
that for the host to notice the configuration change, it must
be either physically disconnected and reconnected, or forced
to rescan the USB bus in a system-specific
way. When &os; is running on the host, &man.usbconfig.8;
reset can be used. This also must be done
after loading usb_template.ko if the
USB host was already connected to the
USB OTG socket.The hw.usb.template sysctl
is set to 0 by default, making &os; work as a
USB Mass Storage target. Both
&man.usb.template.4; and &man.cfumass.4; kernel modules must
be loaded. &man.cfumass.4; interfaces to the CTL subsystem,
the same one that is used for iSCSI or
Fibre Channel targets. On the host side,
USB Mass Storage initiators can only access
a single LUN,
LUN 0.USB Mass Storage does not require the
&man.ctld.8; daemon to be running, although it can be used if
desired. This is different from iSCSI.
Thus, there are two ways to configure the target:
&man.ctladm.8;, or &man.ctld.8;. Both require the
cfumass.ko kernel module to be loaded.
The module can be loaded manually:&prompt.root; kldload cfumassIf cfumass.ko has not been built into
the kernel, /boot/loader.conf can be set
to load the module at boot:cfumass_load="YES"A LUN can be created without the
&man.ctld.8; daemon:&prompt.root; ctladm create -b block -o file=/data/target0This presents the contents of the image file
/data/target0 as a LUN
to the USB host. The file must exist
before executing the command. To configure the
LUN at system startup, add the command to
/etc/rc.local.&man.ctld.8; can also be used to manage
LUNs. Create
/etc/ctl.conf, add a line to
/etc/rc.conf to make sure &man.ctld.8; is
automatically started at boot, and then start the
daemon.This is an example of a simple
/etc/ctl.conf configuration file. Refer
to &man.ctl.conf.5; for a more complete description of the
options.target naa.50015178f369f092 {
lun 0 {
path /data/target0
size 4G
}
}The example creates a single target with a single
LUN. The
naa.50015178f369f092 is a device identifier
composed of 32 random hexadecimal digits. The
path line defines the full path to a file
or zvol backing the LUN. That file must
exist before starting &man.ctld.8;. The second line is
optional and specifies the size of the
LUN.To make sure the &man.ctld.8; daemon is started at
boot, add this line to
/etc/rc.conf:ctld_enable="YES"To start &man.ctld.8; now, run this command:&prompt.root; service ctld startAs the &man.ctld.8; daemon is started, it reads
/etc/ctl.conf. If this file is edited
after the daemon starts, reload the changes so they take
effect immediately:&prompt.root; service ctld reloadCreating and Using CD MediaMikeMeyerContributed by CD-ROMscreatingCompact Disc (CD) media provide a number
of features that differentiate them from conventional disks.
They are designed so that they can be read continuously without
delays to move the head between tracks. While
CD media do have tracks, these refer to a
section of data to be read continuously, and not a physical
property of the disk. The ISO 9660 file
system was designed to deal with these differences.ISO
9660file systemsISO 9660CD burnerATAPIThe &os; Ports Collection provides several utilities for
burning and duplicating audio and data CDs.
This chapter demonstrates the use of several command line
utilities. For CD burning software with a
graphical utility, consider installing the
sysutils/xcdroast or
sysutils/k3b packages or ports.Supported DevicesMarcFonvieilleContributed by CD burnerATAPI/CAM driverThe GENERIC kernel provides support
for SCSI, USB, and
ATAPI CD readers and
burners. If a custom kernel is used, the options that need to
be present in the kernel configuration file vary by the type
of device.For a SCSI burner, make sure these
options are present:device scbus # SCSI bus (required for ATA/SCSI)
device da # Direct Access (disks)
device pass # Passthrough device (direct ATA/SCSI access)
device cd # needed for CD and DVD burnersFor a USB burner, make sure these
options are present:device scbus # SCSI bus (required for ATA/SCSI)
device da # Direct Access (disks)
device pass # Passthrough device (direct ATA/SCSI access)
device cd # needed for CD and DVD burners
device uhci # provides USB 1.x support
device ohci # provides USB 1.x support
device ehci # provides USB 2.0 support
device xhci # provides USB 3.0 support
device usb # USB Bus (required)
device umass # Disks/Mass storage - Requires scbus and daFor an ATAPI burner, make sure these
options are present:device ata # Legacy ATA/SATA controllers
device scbus # SCSI bus (required for ATA/SCSI)
device pass # Passthrough device (direct ATA/SCSI access)
device cd # needed for CD and DVD burnersOn &os; versions prior to 10.x, this line is also
needed in the kernel configuration file if the burner is an
ATAPI device:device atapicamAlternately, this driver can be loaded at boot time by
adding the following line to
/boot/loader.conf:atapicam_load="YES"This will require a reboot of the system as this driver
can only be loaded at boot time.To verify that &os; recognizes the device, run
dmesg and look for an entry for the device.
On systems prior to 10.x, the device name in the first line of
the output will be acd0 instead of
cd0.&prompt.user; dmesg | grep cd
cd0 at ahcich1 bus 0 scbus1 target 0 lun 0
cd0: <HL-DT-ST DVDRAM GU70N LT20> Removable CD-ROM SCSI-0 device
cd0: Serial Number M3OD3S34152
cd0: 150.000MB/s transfers (SATA 1.x, UDMA6, ATAPI 12bytes, PIO 8192bytes)
cd0: Attempt to query device size failed: NOT READY, Medium not present - tray closedBurning a CDIn &os;, cdrecord can be used to burn
CDs. This command is installed with the
sysutils/cdrtools package or port.While cdrecord has many options, basic
usage is simple. Specify the name of the
ISO file to burn and, if the system has
multiple burner devices, specify the name of the device to
use:&prompt.root; cdrecord dev=deviceimagefile.isoTo determine the device name of the burner, use
which might produce results like
this:CD-ROMsburning&prompt.root; cdrecord -scanbus
ProDVD-ProBD-Clone 3.00 (amd64-unknown-freebsd10.0) Copyright (C) 1995-2010 Jörg Schilling
Using libscg version 'schily-0.9'
scsibus0:
0,0,0 0) 'SEAGATE ' 'ST39236LW ' '0004' Disk
0,1,0 1) 'SEAGATE ' 'ST39173W ' '5958' Disk
0,2,0 2) *
0,3,0 3) 'iomega ' 'jaz 1GB ' 'J.86' Removable Disk
0,4,0 4) 'NEC ' 'CD-ROM DRIVE:466' '1.26' Removable CD-ROM
0,5,0 5) *
0,6,0 6) *
0,7,0 7) *
scsibus1:
1,0,0 100) *
1,1,0 101) *
1,2,0 102) *
1,3,0 103) *
1,4,0 104) *
1,5,0 105) 'YAMAHA ' 'CRW4260 ' '1.0q' Removable CD-ROM
1,6,0 106) 'ARTEC ' 'AM12S ' '1.06' Scanner
1,7,0 107) *Locate the entry for the CD burner and
use the three numbers separated by commas as the value for
. In this case, the Yamaha burner device
is 1,5,0, so the appropriate input to
specify that device is . Refer to
the manual page for cdrecord for other ways
to specify this value and for information on writing audio
tracks and controlling the write speed.Alternately, run the following command to get the device
address of the burner:&prompt.root; camcontrol devlist
<MATSHITA CDRW/DVD UJDA740 1.00> at scbus1 target 0 lun 0 (cd0,pass0)Use the numeric values for scbus,
target, and lun. For
this example, 1,0,0 is the device name to
use.Writing Data to an ISO File
SystemIn order to produce a data CD, the data
files that are going to make up the tracks on the
CD must be prepared before they can be
burned to the CD. In &os;,
sysutils/cdrtools installs
mkisofs, which can be used to produce an
ISO 9660 file system that is an image of a
directory tree within a &unix; file system. The simplest
usage is to specify the name of the ISO
file to create and the path to the files to place into the
ISO 9660 file system:&prompt.root; mkisofs -o imagefile.iso/path/to/treefile systemsISO 9660This command maps the file names in the specified path to
names that fit the limitations of the standard
ISO 9660 file system, and will exclude
files that do not meet the standard for ISO
file systems.file systemsJolietA number of options are available to overcome the
restrictions imposed by the standard. In particular,
enables the Rock Ridge extensions common
to &unix; systems and enables Joliet
extensions used by µsoft; systems.For CDs that are going to be used only
on &os; systems, can be used to disable
all filename restrictions. When used with
, it produces a file system image that is
identical to the specified &os; tree, even if it violates the
ISO 9660 standard.CD-ROMscreating bootableThe last option of general use is .
This is used to specify the location of a boot image for use
in producing an El Torito bootable
CD. This option takes an argument which is
the path to a boot image from the top of the tree being
written to the CD. By default,
mkisofs creates an ISO
image in floppy disk emulation mode, and thus
expects the boot image to be exactly 1200, 1440 or
2880 KB in size. Some boot loaders, like the one used by
the &os; distribution media, do not use emulation mode. In
this case, should be used. So,
if /tmp/myboot holds a bootable &os;
system with the boot image in
/tmp/myboot/boot/cdboot, this command
would produce
/tmp/bootable.iso:&prompt.root; mkisofs -R -no-emul-boot -b boot/cdboot -o /tmp/bootable.iso /tmp/mybootThe resulting ISO image can be mounted
as a memory disk with:&prompt.root; mdconfig -a -t vnode -f /tmp/bootable.iso -u 0
&prompt.root; mount -t cd9660 /dev/md0 /mntOne can then verify that /mnt and
/tmp/myboot are identical.There are many other options available for
mkisofs to fine-tune its behavior. Refer
to &man.mkisofs.8; for details.It is possible to copy a data CD to
an image file that is functionally equivalent to the image
file created with mkisofs. To do so, use
dd with the device name as the input
file and the name of the ISO to create as
the output file:&prompt.root; dd if=/dev/cd0 of=file.iso bs=2048The resulting image file can be burned to
CD as described in .Using Data CDsOnce an ISO has been burned to a
CD, it can be mounted by specifying the
file system type, the name of the device containing the
CD, and an existing mount point:&prompt.root; mount -t cd9660 /dev/cd0/mntSince mount assumes that a file system
is of type ufs, a Incorrect
super block error will occur if -t
cd9660 is not included when mounting a data
CD.While any data CD can be mounted this
way, disks with certain ISO 9660 extensions
might behave oddly. For example, Joliet disks store all
filenames in two-byte Unicode characters. If some non-English
characters show up as question marks, specify the local
charset with . For more information, refer
to &man.mount.cd9660.8;.In order to do this character conversion with the help
of , the kernel requires the
cd9660_iconv.ko module to be loaded.
This can be done either by adding this line to
loader.conf:cd9660_iconv_load="YES"and then rebooting the machine, or by directly loading
the module with kldload.Occasionally, Device not configured
will be displayed when trying to mount a data
CD. This usually means that the
CD drive has not detected a disk in
the tray, or that the drive is not visible on the bus. It
can take a couple of seconds for a CD
drive to detect media, so be
patient.Sometimes, a SCSI
CD drive may be missed because it did not
have enough time to answer the bus reset. To resolve this,
a custom kernel can be created which increases the default
SCSI delay. Add the following option to
the custom kernel configuration file and rebuild the kernel
using the instructions in :options SCSI_DELAY=15000This tells the SCSI bus to pause 15
seconds during boot, to give the CD
drive every possible chance to answer the bus reset.It is possible to burn a file directly to
CD, without creating an
ISO 9660 file system. This is known as
burning a raw data CD and some people do
this for backup purposes.This type of disk can not be mounted as a normal data
CD. In order to retrieve the data burned
to such a CD, the data must be read from
the raw device node. For example, this command will extract
a compressed tar file located on the second
CD device into the current working
directory:&prompt.root; tar xzvf /dev/cd1 In order to mount a data CD, the
data must be written using
mkisofs.Duplicating Audio CDsTo duplicate an audio CD, extract the
audio data from the CD to a series of
files, then write these files to a blank
CD. describes how to
duplicate and burn an audio CD. If the
&os; version is less than 10.0 and the device is
ATAPI, the module
must be first loaded using the instructions in .Duplicating an Audio CDThe sysutils/cdrtools package or
port installs cdda2wav. This command
can be used to extract all of the audio tracks, with each
track written to a separate WAV file in
the current working directory:&prompt.user; cdda2wav -vall -B -OwavA device name does not need to be specified if there
is only one CD device on the system.
Refer to the cdda2wav manual page for
instructions on how to specify a device and to learn more
about the other options available for this command.Use cdrecord to write the
.wav files:&prompt.user; cdrecord -v dev=2,0 -dao -useinfo *.wavMake sure that 2,0 is set
appropriately, as described in .Creating and Using DVD MediaMarcFonvieilleContributed by AndyPolyakovWith inputs from DVDburningCompared to the CD, the
DVD is the next generation of optical media
storage technology. The DVD can hold more
data than any CD and is the standard for
video publishing.Five physical recordable formats can be defined for a
recordable DVD:DVD-R: This was the first DVD
recordable format available. The DVD-R standard is defined
by the DVD
Forum. This format is write once.DVD-RW: This is the rewritable
version of the DVD-R standard. A
DVD-RW can be rewritten about 1000
times.DVD-RAM: This is a rewritable format
which can be seen as a removable hard drive. However, this
media is not compatible with most
DVD-ROM drives and DVD-Video players as
only a few DVD writers support the
DVD-RAM format. Refer to for more information on
DVD-RAM use.DVD+RW: This is a rewritable format
defined by the DVD+RW
Alliance. A DVD+RW can be
rewritten about 1000 times.DVD+R: This format is the write once variation of the
DVD+RW format.A single layer recordable DVD can hold up
to 4,700,000,000 bytes which is actually 4.38 GB or
4485 MB as 1 kilobyte is 1024 bytes.A distinction must be made between the physical media and
the application. For example, a DVD-Video is a specific file
layout that can be written on any recordable
DVD physical media such as DVD-R, DVD+R, or
DVD-RW. Before choosing the type of media,
ensure that both the burner and the DVD-Video player are
compatible with the media under consideration.ConfigurationTo perform DVD recording, use
&man.growisofs.1;. This command is part of the
sysutils/dvd+rw-tools utilities which
support all DVD media types.These tools use the SCSI subsystem to
access the devices, therefore ATAPI/CAM support must be loaded
or statically compiled into the kernel. This support is not
needed if the burner uses the USB
interface. Refer to for more
details on USB device configuration.DMA access must also be enabled for
ATAPI devices, by adding the following line
to /boot/loader.conf:hw.ata.atapi_dma="1"Before attempting to use
dvd+rw-tools, consult the Hardware
Compatibility Notes.For a graphical user interface, consider using
sysutils/k3b which provides a user
friendly interface to &man.growisofs.1; and many other
burning tools.Burning Data DVDsSince &man.growisofs.1; is a front-end to mkisofs, it will invoke
&man.mkisofs.8; to create the file system layout and perform
the write on the DVD. This means that an
image of the data does not need to be created before the
burning process.To burn to a DVD+R or a DVD-R the data in
/path/to/data, use the following
command:&prompt.root; growisofs -dvd-compat -Z /dev/cd0 -J -R /path/to/dataIn this example, is passed to
&man.mkisofs.8; to create an ISO 9660 file system with Joliet
and Rock Ridge extensions. Refer to &man.mkisofs.8; for more
details.For the initial session recording, is
used for both single and multiple sessions. Replace
/dev/cd0, with the name of the
DVD device. Using
indicates that the disk will be
closed and that the recording will be unappendable. This
should also provide better media compatibility with
DVD-ROM drives.To burn a pre-mastered image, such as
imagefile.iso, use:&prompt.root; growisofs -dvd-compat -Z /dev/cd0=imagefile.isoThe write speed should be detected and automatically set
according to the media and the drive being used. To force the
write speed, use . Refer to
&man.growisofs.1; for example usage.In order to support working files larger than 4.38GB, an
UDF/ISO-9660 hybrid file system must be created by passing
to &man.mkisofs.8; and
all related programs, such as &man.growisofs.1;. This is
required only when creating an ISO image file or when
writing files directly to a disk. Since a disk created this
way must be mounted as an UDF file system with
&man.mount.udf.8;, it will be usable only on an UDF aware
operating system. Otherwise it will look as if it contains
corrupted files.To create this type of ISO file:&prompt.user; mkisofs -R -J -udf -iso-level 3 -o imagefile.iso/path/to/dataTo burn files directly to a disk:&prompt.root; growisofs -dvd-compat -udf -iso-level 3 -Z /dev/cd0 -J -R /path/to/dataWhen an ISO image already contains large files, no
additional options are required for &man.growisofs.1; to
burn that image on a disk.Be sure to use an up-to-date version of
sysutils/cdrtools, which contains
&man.mkisofs.8;, as an older version may not contain large
files support. If the latest version does not work, install
sysutils/cdrtools-devel and read its
&man.mkisofs.8;.Burning a DVD-VideoDVDDVD-VideoA DVD-Video is a specific file layout based on the ISO
9660 and micro-UDF (M-UDF) specifications. Since DVD-Video
presents a specific data structure hierarchy, a particular
program such as multimedia/dvdauthor is
needed to author the DVD.If an image of the DVD-Video file system already exists,
it can be burned in the same way as any other image. If
dvdauthor was used to make the
DVD and the result is in
/path/to/video, the following command
should be used to burn the DVD-Video:&prompt.root; growisofs -Z /dev/cd0 -dvd-video /path/to/video is passed to &man.mkisofs.8;
to instruct it to create a DVD-Video file system layout.
This option implies the
&man.growisofs.1; option.Using a DVD+RWDVDDVD+RWUnlike CD-RW, a virgin DVD+RW needs to
be formatted before first use. It is
recommended to let &man.growisofs.1; take
care of this automatically whenever appropriate. However, it
is possible to use dvd+rw-format to format
the DVD+RW:&prompt.root; dvd+rw-format /dev/cd0Only perform this operation once and keep in mind that
only virgin DVD+RW medias need to be
formatted. Once formatted, the DVD+RW can
be burned as usual.To burn a totally new file system and not just append some
data onto a DVD+RW, the media does not need
to be blanked first. Instead, write over the previous
recording like this:&prompt.root; growisofs -Z /dev/cd0 -J -R /path/to/newdataThe DVD+RW format supports appending
data to a previous recording. This operation consists of
merging a new session to the existing one as it is not
considered to be multi-session writing. &man.growisofs.1;
will grow the ISO 9660 file system
present on the media.For example, to append data to a
DVD+RW, use the following:&prompt.root; growisofs -M /dev/cd0 -J -R /path/to/nextdataThe same &man.mkisofs.8; options used to burn the
initial session should be used during next writes.Use for better media
compatibility with DVD-ROM drives. When
using DVD+RW, this option will not
prevent the addition of data.To blank the media, use:&prompt.root; growisofs -Z /dev/cd0=/dev/zeroUsing a DVD-RWDVDDVD-RWA DVD-RW accepts two disc formats:
incremental sequential and restricted overwrite. By default,
DVD-RW discs are in sequential
format.A virgin DVD-RW can be directly written
without being formatted. However, a non-virgin
DVD-RW in sequential format needs to be
blanked before writing a new initial session.To blank a DVD-RW in sequential
mode:&prompt.root; dvd+rw-format -blank=full /dev/cd0A full blanking using will
take about one hour on a 1x media. A fast blanking can be
performed using , if the
DVD-RW will be recorded in Disk-At-Once
(DAO) mode. To burn the DVD-RW in DAO
mode, use the command:&prompt.root; growisofs -use-the-force-luke=dao -Z /dev/cd0=imagefile.isoSince &man.growisofs.1; automatically attempts to detect
fast blanked media and engage DAO write,
should not be
required.One should instead use restricted overwrite mode with
any DVD-RW as this format is more
flexible than the default of incremental sequential.To write data on a sequential DVD-RW,
use the same instructions as for the other
DVD formats:&prompt.root; growisofs -Z /dev/cd0 -J -R /path/to/dataTo append some data to a previous recording, use
with &man.growisofs.1;. However, if data
is appended on a DVD-RW in incremental
sequential mode, a new session will be created on the disc and
the result will be a multi-session disc.A DVD-RW in restricted overwrite format
does not need to be blanked before a new initial session.
Instead, overwrite the disc with . It is
also possible to grow an existing ISO 9660 file system written
on the disc with . The result will be a
one-session DVD.To put a DVD-RW in restricted overwrite
format, the following command must be used:&prompt.root; dvd+rw-format /dev/cd0To change back to sequential format, use:&prompt.root; dvd+rw-format -blank=full /dev/cd0Multi-SessionFew DVD-ROM drives support
multi-session DVDs and most of the time only read the first
session. DVD+R, DVD-R and DVD-RW in
sequential format can accept multiple sessions. The notion
of multiple sessions does not exist for the
DVD+RW and the DVD-RW
restricted overwrite formats.Using the following command after an initial non-closed
session on a DVD+R, DVD-R, or DVD-RW in
sequential format, will add a new session to the disc:&prompt.root; growisofs -M /dev/cd0 -J -R /path/to/nextdataUsing this command with a DVD+RW or a
DVD-RW in restricted overwrite mode will
append data while merging the new session to the existing one.
The result will be a single-session disc. Use this method to
add data after an initial write on these types of
media.Since some space on the media is used between each
session to mark the end and start of sessions, one should
add sessions with a large amount of data to optimize media
space. The number of sessions is limited to 154 for a
DVD+R, about 2000 for a DVD-R, and 127 for a DVD+R Double
Layer.For More InformationTo obtain more information about a DVD,
use dvd+rw-mediainfo
/dev/cd0 while the
disc in the specified drive.More information about
dvd+rw-tools can be found in
&man.growisofs.1;, on the dvd+rw-tools
web site, and in the cdwrite
mailing list archives.When creating a problem report related to the use of
dvd+rw-tools, always include the
output of dvd+rw-mediainfo.Using a DVD-RAMDVDDVD-RAMDVD-RAM writers can use either a
SCSI or ATAPI interface.
For ATAPI devices, DMA access has to be
enabled by adding the following line to
/boot/loader.conf:hw.ata.atapi_dma="1"A DVD-RAM can be seen as a removable
hard drive. Like any other hard drive, the
DVD-RAM must be formatted before it can be
used. In this example, the whole disk space will be formatted
with a standard UFS2 file system:&prompt.root; dd if=/dev/zero of=/dev/acd0 bs=2k count=1
&prompt.root; bsdlabel -Bw acd0
&prompt.root; newfs /dev/acd0The DVD device,
acd0, must be changed according to the
configuration.Once the DVD-RAM has been formatted, it
can be mounted as a normal hard drive:&prompt.root; mount /dev/acd0/mntOnce mounted, the DVD-RAM will be both
readable and writeable.Creating and Using Floppy DisksThis section explains how to format a 3.5 inch floppy disk
in &os;.Steps to Format a FloppyA floppy disk needs to be low-level formatted before it
can be used. This is usually done by the vendor, but
formatting is a good way to check media integrity. To
low-level format the floppy disk on &os;, use
&man.fdformat.1;. When using this utility, make note of any
error messages, as these can help determine if the disk is
good or bad.To format the floppy, insert a new 3.5 inch floppy disk
into the first floppy drive and issue:&prompt.root; /usr/sbin/fdformat -f 1440 /dev/fd0After low-level formatting the disk, create a disk label
as it is needed by the system to determine the size of the
disk and its geometry. The supported geometry values are
listed in /etc/disktab.To write the disk label, use &man.bsdlabel.8;:&prompt.root; /sbin/bsdlabel -B -w /dev/fd0 fd1440The floppy is now ready to be high-level formatted with
a file system. The floppy's file system can be either UFS
or FAT, where FAT is generally a better choice for
floppies.To format the floppy with FAT, issue:&prompt.root; /sbin/newfs_msdos /dev/fd0The disk is now ready for use. To use the floppy, mount it
with &man.mount.msdosfs.8;. One can also install and use
emulators/mtools from the Ports
Collection.Backup BasicsImplementing a backup plan is essential in order to have the
ability to recover from disk failure, accidental file deletion,
random file corruption, or complete machine destruction,
including destruction of on-site backups.The backup type and schedule will vary, depending upon the
importance of the data, the granularity needed for file
restores, and the amount of acceptable downtime. Some possible
backup techniques include:Archives of the whole system, backed up onto permanent,
off-site media. This provides protection against all of the
problems listed above, but is slow and inconvenient to
restore from, especially for non-privileged users.File system snapshots, which are useful for restoring
deleted files or previous versions of files.Copies of whole file systems or disks which are
synchronized with another system on the network using a
scheduled net/rsync.Hardware or software RAID, which
minimizes or avoids downtime when a disk fails.Typically, a mix of backup techniques is used. For
example, one could create a schedule to automate a weekly, full
system backup that is stored off-site and to supplement this
backup with hourly ZFS snapshots. In addition, one could make a
manual backup of individual directories or files before making
file edits or deletions.This section describes some of the utilities which can be
used to create and manage backups on a &os; system.File System Backupsbackup softwaredump / restoredumprestoreThe traditional &unix; programs for backing up a file
system are &man.dump.8;, which creates the backup, and
&man.restore.8;, which restores the backup. These utilities
work at the disk block level, below the abstractions of the
files, links, and directories that are created by file
systems. Unlike other backup software,
dump backs up an entire file system and is
unable to backup only part of a file system or a directory
tree that spans multiple file systems. Instead of writing
files and directories, dump writes the raw
data blocks that comprise files and directories.If dump is used on the root
directory, it will not back up /home,
/usr or many other directories since
these are typically mount points for other file systems or
symbolic links into those file systems.When used to restore data, restore
stores temporary files in /tmp/ by
default. When using a recovery disk with a small
/tmp, set TMPDIR to a
directory with more free space in order for the restore to
succeed.When using dump, be aware that some
quirks remain from its early days in Version 6 of
AT&T &unix;,circa 1975. The default parameters assume a
backup to a 9-track tape, rather than to another type of media
or to the high-density tapes available today. These defaults
must be overridden on the command line..rhostsIt is possible to backup a file system across the network
to a another system or to a tape drive attached to another
computer. While the &man.rdump.8; and &man.rrestore.8;
utilities can be used for this purpose, they are not
considered to be secure.Instead, one can use dump and
restore in a more secure fashion over an
SSH connection. This example creates a
full, compressed backup of /usr and sends
the backup file to the specified host over a
SSH connection.Using dump over
ssh&prompt.root; /sbin/dump -0uan -f - /usr | gzip -2 | ssh -c blowfish \
targetuser@targetmachine.example.com dd of=/mybigfiles/dump-usr-l0.gzThis example sets RSH in order to write the
backup to a tape drive on a remote system over a
SSH connection:Using dump over
ssh with RSH
Set&prompt.root; env RSH=/usr/bin/ssh /sbin/dump -0uan -f targetuser@targetmachine.example.com:/dev/sa0 /usrDirectory Backupsbackup softwaretarSeveral built-in utilities are available for backing up
and restoring specified files and directories as
needed.A good choice for making a backup of all of the files in a
directory is &man.tar.1;. This utility dates back to Version
6 of AT&T &unix; and by default assumes a recursive backup
to a local tape device. Switches can be used to instead
specify the name of a backup file.tarThis example creates a compressed backup of the current
directory and saves it to
/tmp/mybackup.tgz. When creating a
backup file, make sure that the backup is not saved to the
same directory that is being backed up.Backing Up the Current Directory with
tar&prompt.root; tar czvf /tmp/mybackup.tgz . To restore the entire backup, cd into
the directory to restore into and specify the name of the
backup. Note that this will overwrite any newer versions of
files in the restore directory. When in doubt, restore to a
temporary directory or specify the name of the file within the
backup to restore.Restoring Up the Current Directory with
tar&prompt.root; tar xzvf /tmp/mybackup.tgzThere are dozens of available switches which are described
in &man.tar.1;. This utility also supports the use of exclude
patterns to specify which files should not be included when
backing up the specified directory or restoring files from a
backup.backup softwarecpioTo create a backup using a specified list of files and
directories, &man.cpio.1; is a good choice. Unlike
tar, cpio does not know
how to walk the directory tree and it must be provided the
list of files to backup.For example, a list of files can be created using
ls or find. This
example creates a recursive listing of the current directory
which is then piped to cpio in order to
create an output backup file named
/tmp/mybackup.cpio.Using ls and cpio
to Make a Recursive Backup of the Current Directory&prompt.root; ls -R | cpio -ovF /tmp/mybackup.cpiobackup softwarepaxpaxPOSIXIEEEA backup utility which tries to bridge the features
provided by tar and cpio
is &man.pax.1;. Over the years, the various versions of
tar and cpio became
slightly incompatible. &posix; created pax
which attempts to read and write many of the various
cpio and tar formats,
plus new formats of its own.The pax equivalent to the previous
examples would be:Backing Up the Current Directory with
pax&prompt.root; pax -wf /tmp/mybackup.pax .Using Data Tapes for Backupstape mediaWhile tape technology has continued to evolve, modern
backup systems tend to combine off-site backups with local
removable media. &os; supports any tape drive that uses
SCSI, such as LTO or
DAT. There is limited support for
SATA and USB tape
drives.For SCSI tape devices, &os; uses the
&man.sa.4; driver and the /dev/sa0,
/dev/nsa0, and
/dev/esa0 devices. The physical device
name is /dev/sa0. When
/dev/nsa0 is used, the backup application
will not rewind the tape after writing a file, which allows
writing more than one file to a tape. Using
/dev/esa0 ejects the tape after the
device is closed.In &os;, mt is used to control
operations of the tape drive, such as seeking through files on
a tape or writing tape control marks to the tape. For
example, the first three files on a tape can be preserved by
skipping past them before writing a new file:&prompt.root; mt -f /dev/nsa0 fsf 3This utility supports many operations. Refer to
&man.mt.1; for details.To write a single file to tape using
tar, specify the name of the tape device
and the file to backup:&prompt.root; tar cvf /dev/sa0 fileTo recover files from a tar archive
on tape into the current directory:&prompt.root; tar xvf /dev/sa0To backup a UFS file system, use
dump. This examples backs up
/usr without rewinding the tape when
finished:&prompt.root; dump -0aL -b64 -f /dev/nsa0 /usrTo interactively restore files from a
dump file on tape into the current
directory:&prompt.root; restore -i -f /dev/nsa0Third-Party Backup Utilitiesbackup softwareThe &os; Ports Collection provides many third-party
utilities which can be used to schedule the creation of
backups, simplify tape backup, and make backups easier and
more convenient. Many of these applications are client/server
based and can be used to automate the backups of a single
system or all of the computers in a network.Popular utilities include
Amanda,
Bacula,
rsync, and
duplicity.Emergency RecoveryIn addition to regular backups, it is recommended to
perform the following steps as part of an emergency
preparedness plan.bsdlabelCreate a print copy of the output of the following
commands:gpart showmore /etc/fstabdmesglivefs
CDStore this printout and a copy of the installation media
in a secure location. Should an emergency restore be
needed, boot into the installation media and select
Live CD to access a rescue shell. This
rescue mode can be used to view the current state of the
system, and if needed, to reformat disks and restore data
from backups.The installation media for
&os;/&arch.i386; &rel2.current;-RELEASE does not
include a rescue shell. For this version, instead
download and burn a Livefs CD image from
ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/&arch.i386;/ISO-IMAGES/&rel2.current;/&os;-&rel2.current;-RELEASE-&arch.i386;-livefs.iso.Next, test the rescue shell and the backups. Make notes
of the procedure. Store these notes with the media, the
printouts, and the backups. These notes may prevent the
inadvertent destruction of the backups while under the stress
of performing an emergency recovery.For an added measure of security, store the latest backup
at a remote location which is physically separated from the
computers and disk drives by a significant distance.Memory DisksMarcFonvieilleReorganized and enhanced by In addition to physical disks, &os; also supports the
creation and use of memory disks. One possible use for a
memory disk is to access the contents of an
ISO file system without the overhead of first
burning it to a CD or DVD,
then mounting the CD/DVD media.In &os;, the &man.md.4; driver is used to provide support
for memory disks. The GENERIC kernel
includes this driver. When using a custom kernel configuration
file, ensure it includes this line:device mdAttaching and Detaching Existing ImagesdisksmemoryTo mount an existing file system image, use
mdconfig to specify the name of the
ISO file and a free unit number. Then,
refer to that unit number to mount it on an existing mount
point. Once mounted, the files in the ISO
will appear in the mount point. This example attaches
diskimage.iso to the memory device
/dev/md0 then mounts that memory device
on /mnt:&prompt.root; mdconfig -f diskimage.iso -u 0
&prompt.root; mount /dev/md0/mntIf a unit number is not specified with
, mdconfig will
automatically allocate an unused memory device and output
the name of the allocated unit, such as
md4. Refer to &man.mdconfig.8; for more
details about this command and its options.disksdetaching a memory diskWhen a memory disk is no longer in use, its resources
should be released back to the system. First, unmount the
file system, then use mdconfig to detach
the disk from the system and release its resources. To
continue this example:&prompt.root; umount /mnt
&prompt.root; mdconfig -d -u 0To determine if any memory disks are still attached to the
system, type mdconfig -l.Creating a File- or Memory-Backed Memory Diskdisksmemory file system&os; also supports memory disks where the storage to use
is allocated from either a hard disk or an area of memory.
The first method is commonly referred to as a file-backed file
system and the second method as a memory-backed file system.
Both types can be created using
mdconfig.To create a new memory-backed file system, specify a type
of swap and the size of the memory disk to
create. Then, format the memory disk with a file system and
mount as usual. This example creates a 5M memory disk on unit
1. That memory disk is then formatted with
the UFS file system before it is
mounted:&prompt.root; mdconfig -a -t swap -s 5m -u 1
&prompt.root; newfs -U md1
/dev/md1: 5.0MB (10240 sectors) block size 16384, fragment size 2048
using 4 cylinder groups of 1.27MB, 81 blks, 192 inodes.
with soft updates
super-block backups (for fsck -b #) at:
160, 2752, 5344, 7936
&prompt.root; mount /dev/md1/mnt
&prompt.root; df /mnt
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/md1 4718 4 4338 0% /mntTo create a new file-backed memory disk, first allocate an
area of disk to use. This example creates an empty 5K file
named newimage:&prompt.root; dd if=/dev/zero of=newimage bs=1k count=5k
5120+0 records in
5120+0 records outNext, attach that file to a memory disk, label the memory
disk and format it with the UFS file
system, mount the memory disk, and verify the size of the
file-backed disk:&prompt.root; mdconfig -f newimage -u 0
&prompt.root; bsdlabel -w md0 auto
&prompt.root; newfs md0a
/dev/md0a: 5.0MB (10224 sectors) block size 16384, fragment size 2048
using 4 cylinder groups of 1.25MB, 80 blks, 192 inodes.
super-block backups (for fsck -b #) at:
160, 2720, 5280, 7840
&prompt.root; mount /dev/md0a /mnt
&prompt.root; df /mnt
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/md0a 4710 4 4330 0% /mntIt takes several commands to create a file- or
memory-backed file system using mdconfig.
&os; also comes with mdmfs which
automatically configures a memory disk, formats it with the
UFS file system, and mounts it. For
example, after creating newimage
with dd, this one command is equivalent to
running the bsdlabel,
newfs, and mount
commands shown above:&prompt.root; mdmfs -F newimage -s 5m md0/mntTo instead create a new memory-based memory disk with
mdmfs, use this one command:&prompt.root; mdmfs -s 5m md1/mntIf the unit number is not specified,
mdmfs will automatically select an unused
memory device. For more details about
mdmfs, refer to &man.mdmfs.8;.File System SnapshotsTomRhodesContributed by file systemssnapshots&os; offers a feature in conjunction with
Soft Updates: file system
snapshots.UFS snapshots allow a user to create images of specified
file systems, and treat them as a file. Snapshot files must be
created in the file system that the action is performed on, and
a user may create no more than 20 snapshots per file system.
Active snapshots are recorded in the superblock so they are
persistent across unmount and remount operations along with
system reboots. When a snapshot is no longer required, it can
be removed using &man.rm.1;. While snapshots may be removed in
any order, all the used space may not be acquired because
another snapshot will possibly claim some of the released
blocks.The un-alterable file flag is set
by &man.mksnap.ffs.8; after initial creation of a snapshot file.
&man.unlink.1; makes an exception for snapshot files since it
allows them to be removed.Snapshots are created using &man.mount.8;. To place a
snapshot of /var in the
file /var/snapshot/snap, use the following
command:&prompt.root; mount -u -o snapshot /var/snapshot/snap /varAlternatively, use &man.mksnap.ffs.8; to create the
snapshot:&prompt.root; mksnap_ffs /var /var/snapshot/snapOne can find snapshot files on a file system, such as
/var, using
&man.find.1;:&prompt.root; find /var -flags snapshotOnce a snapshot has been created, it has several
uses:Some administrators will use a snapshot file for backup
purposes, because the snapshot can be transferred to
CDs or tape.The file system integrity checker, &man.fsck.8;, may be
run on the snapshot. Assuming that the file system was
clean when it was mounted, this should always provide a
clean and unchanging result.Running &man.dump.8; on the snapshot will produce a dump
file that is consistent with the file system and the
timestamp of the snapshot. &man.dump.8; can also take a
snapshot, create a dump image, and then remove the snapshot
in one command by using .The snapshot can be mounted as a frozen image of the
file system. To &man.mount.8; the snapshot
/var/snapshot/snap run:&prompt.root; mdconfig -a -t vnode -o readonly -f /var/snapshot/snap -u 4
&prompt.root; mount -r /dev/md4 /mntThe frozen /var is now available
through /mnt. Everything will initially be
in the same state it was during the snapshot creation time. The
only exception is that any earlier snapshots will appear as zero
length files. To unmount the snapshot, use:&prompt.root; umount /mnt
&prompt.root; mdconfig -d -u 4For more information about and
file system snapshots, including technical papers, visit
Marshall Kirk McKusick's website at http://www.mckusick.com/.Disk Quotasaccountingdisk spacedisk quotasDisk quotas can be used to limit the amount of disk space or
the number of files a user or members of a group may allocate on
a per-file system basis. This prevents one user or group of
users from consuming all of the available disk space.This section describes how to configure disk quotas for the
UFS file system. To configure quotas on the
ZFS file system, refer to Enabling Disk QuotasTo determine if the &os; kernel provides support for disk
quotas:&prompt.user; sysctl kern.features.ufs_quota
kern.features.ufs_quota: 1In this example, the 1 indicates quota
support. If the value is instead 0, add
the following line to a custom kernel configuration file and
rebuild the kernel using the instructions in :options QUOTANext, enable disk quotas in
/etc/rc.conf:quota_enable="YES"disk quotascheckingNormally on bootup, the quota integrity of each file
system is checked by &man.quotacheck.8;. This program insures
that the data in the quota database properly reflects the data
on the file system. This is a time consuming process that
will significantly affect the time the system takes to boot.
To skip this step, add this variable to
/etc/rc.conf:check_quotas="NO"Finally, edit /etc/fstab to enable
disk quotas on a per-file system basis. To enable per-user
quotas on a file system, add to the
options field in the /etc/fstab entry for
the file system to enable quotas on. For example:/dev/da1s2g /home ufs rw,userquota 1 2To enable group quotas, use
instead. To enable both user and group quotas, separate the
options with a comma:/dev/da1s2g /home ufs rw,userquota,groupquota 1 2By default, quota files are stored in the root directory
of the file system as quota.user and
quota.group. Refer to &man.fstab.5; for
more information. Specifying an alternate location for the
quota files is not recommended.Once the configuration is complete, reboot the system and
/etc/rc will automatically run the
appropriate commands to create the initial quota files for all
of the quotas enabled in
/etc/fstab.In the normal course of operations, there should be no
need to manually run &man.quotacheck.8;, &man.quotaon.8;, or
&man.quotaoff.8;. However, one should read these manual pages
to be familiar with their operation.Setting Quota Limitsdisk quotaslimitsTo
verify that quotas are enabled, run:&prompt.root; quota -vThere should be a one line summary of disk usage and
current quota limits for each file system that quotas are
enabled on.The system is now ready to be assigned quota limits with
edquota.Several options are available to enforce limits on the
amount of disk space a user or group may allocate, and how
many files they may create. Allocations can be limited based
on disk space (block quotas), number of files (inode quotas),
or a combination of both. Each limit is further broken down
into two categories: hard and soft limits.hard limitA hard limit may not be exceeded. Once a user reaches a
hard limit, no further allocations can be made on that file
system by that user. For example, if the user has a hard
limit of 500 kbytes on a file system and is currently using
490 kbytes, the user can only allocate an additional 10
kbytes. Attempting to allocate an additional 11 kbytes will
fail.soft limitSoft limits can be exceeded for a limited amount of time,
known as the grace period, which is one week by default. If a
user stays over their limit longer than the grace period, the
soft limit turns into a hard limit and no further allocations
are allowed. When the user drops back below the soft limit,
the grace period is reset.In the following example, the quota for the test account is being edited.
When edquota is invoked, the editor
specified by EDITOR is opened in order to edit
the quota limits. The default editor is set to
vi.&prompt.root; edquota -u test
Quotas for user test:
/usr: kbytes in use: 65, limits (soft = 50, hard = 75)
inodes in use: 7, limits (soft = 50, hard = 60)
/usr/var: kbytes in use: 0, limits (soft = 50, hard = 75)
inodes in use: 0, limits (soft = 50, hard = 60)There are normally two lines for each file system that has
quotas enabled. One line represents the block limits and the
other represents the inode limits. Change the value to modify
the quota limit. For example, to raise the block limit on
/usr to a soft limit of
500 and a hard limit of
600, change the values in that line as
follows:/usr: kbytes in use: 65, limits (soft = 500, hard = 600)The new quota limits take effect upon exiting the
editor.Sometimes it is desirable to set quota limits on a range
of users. This can be done by first assigning the desired
quota limit to a user. Then, use to
duplicate that quota to a specified range of user IDs
(UIDs). The following command will
duplicate those quota limits for UIDs
10,000 through
19,999:&prompt.root; edquota -p test 10000-19999For more information, refer to &man.edquota.8;.Checking Quota Limits and Disk Usagedisk quotascheckingTo check individual user or group quotas and disk usage,
use &man.quota.1;. A user may only examine their own quota
and the quota of a group they are a member of. Only the
superuser may view all user and group quotas. To get a
summary of all quotas and disk usage for file systems with
quotas enabled, use &man.repquota.8;.Normally, file systems that the user is not using any disk
space on will not show in the output of
quota, even if the user has a quota limit
assigned for that file system. Use to
display those file systems. The following is sample output
from quota -v for a user that has quota
limits on two file systems.Disk quotas for user test (uid 1002):
Filesystem usage quota limit grace files quota limit grace
/usr 65* 50 75 5days 7 50 60
/usr/var 0 50 75 0 50 60grace periodIn this example, the user is currently 15 kbytes over the
soft limit of 50 kbytes on /usr and has 5
days of grace period left. The asterisk *
indicates that the user is currently over the quota
limit.Quotas over NFSNFSQuotas are enforced by the quota subsystem on the
NFS server. The &man.rpc.rquotad.8; daemon
makes quota information available to quota
on NFS clients, allowing users on those
machines to see their quota statistics.On the NFS server, enable
rpc.rquotad by removing the
# from this line in
/etc/inetd.conf:rquotad/1 dgram rpc/udp wait root /usr/libexec/rpc.rquotad rpc.rquotadThen, restart inetd:&prompt.root; service inetd restartEncrypting Disk PartitionsLuckyGreenContributed by shamrock@cypherpunks.todisksencrypting&os; offers excellent online protections against
unauthorized data access. File permissions and Mandatory Access Control (MAC) help
prevent unauthorized users from accessing data while the
operating system is active and the computer is powered up.
However, the permissions enforced by the operating system are
irrelevant if an attacker has physical access to a computer and
can move the computer's hard drive to another system to copy and
analyze the data.Regardless of how an attacker may have come into possession
of a hard drive or powered-down computer, the
GEOM-based cryptographic subsystems built
into &os; are able to protect the data on the computer's file
systems against even highly-motivated attackers with significant
resources. Unlike encryption methods that encrypt individual
files, the built-in gbde and
geli utilities can be used to transparently
encrypt entire file systems. No cleartext ever touches the hard
drive's platter.This chapter demonstrates how to create an encrypted file
system on &os;. It first demonstrates the process using
gbde and then demonstrates the same example
using geli.Disk Encryption with
gbdeThe objective of the &man.gbde.4; facility is to provide a
formidable challenge for an attacker to gain access to the
contents of a cold storage device.
However, if the computer is compromised while up and running
and the storage device is actively attached, or the attacker
has access to a valid passphrase, it offers no protection to
the contents of the storage device. Thus, it is important to
provide physical security while the system is running and to
protect the passphrase used by the encryption
mechanism.This facility provides several barriers to protect the
data stored in each disk sector. It encrypts the contents of
a disk sector using 128-bit AES in
CBC mode. Each sector on the disk is
encrypted with a different AES key. For
more information on the cryptographic design, including how
the sector keys are derived from the user-supplied passphrase,
refer to &man.gbde.4;.&os; provides a kernel module for
gbde which can be loaded with this
command:&prompt.root; kldload geom_bdeIf using a custom kernel configuration file, ensure it
contains this line:options GEOM_BDEThe following example demonstrates adding a new hard drive
to a system that will hold a single encrypted partition that
will be mounted as /private.Encrypting a Partition with
gbdeAdd the New Hard DriveInstall the new drive to the system as explained in
. For the purposes of this
example, a new hard drive partition has been added as
/dev/ad4s1c and
/dev/ad0s1*
represents the existing standard &os; partitions.&prompt.root; ls /dev/ad*
/dev/ad0 /dev/ad0s1b /dev/ad0s1e /dev/ad4s1
/dev/ad0s1 /dev/ad0s1c /dev/ad0s1f /dev/ad4s1c
/dev/ad0s1a /dev/ad0s1d /dev/ad4Create a Directory to Hold gbde
Lock Files&prompt.root; mkdir /etc/gbdeThe gbde lock file
contains information that gbde
requires to access encrypted partitions. Without access
to the lock file, gbde will not
be able to decrypt the data contained in the encrypted
partition without significant manual intervention which is
not supported by the software. Each encrypted partition
uses a separate lock file.Initialize the gbde
PartitionA gbde partition must be
initialized before it can be used. This initialization
needs to be performed only once. This command will open
the default editor, in order to set various configuration
options in a template. For use with the
UFS file system, set the sector_size to
2048:
- &prompt.root; gbde init /dev/ad4s1c -i -L /etc/gbde/ad4s1c.lock
-# $FreeBSD: src/sbin/gbde/template.txt,v 1.1.36.1 2009/08/03 08:13:06 kensmith Exp $
+ &prompt.root; gbde init /dev/ad4s1c -i -L /etc/gbde/ad4s1c.lock
+# $FreeBSD: src/sbin/gbde/template.txt,v 1.1.36.1 2009/08/03 08:13:06 kensmith Exp $
#
# Sector size is the smallest unit of data which can be read or written.
# Making it too small decreases performance and decreases available space.
# Making it too large may prevent filesystems from working. 512 is the
# minimum and always safe. For UFS, use the fragment size
#
sector_size = 2048
[...]Once the edit is saved, the user will be asked twice
to type the passphrase used to secure the data. The
passphrase must be the same both times. The ability of
gbde to protect data depends
entirely on the quality of the passphrase. For tips on
how to select a secure passphrase that is easy to
remember, see http://world.std.com/~reinhold/diceware.htm.This initialization creates a lock file for the
gbde partition. In this
example, it is stored as
/etc/gbde/ad4s1c.lock. Lock files
must end in .lock in order to be correctly
detected by the /etc/rc.d/gbde start
up script.Lock files must be backed up
together with the contents of any encrypted partitions.
Without the lock file, the legitimate owner will be
unable to access the data on the encrypted
partition.Attach the Encrypted Partition to the
Kernel&prompt.root; gbde attach /dev/ad4s1c -l /etc/gbde/ad4s1c.lockThis command will prompt to input the passphrase that
was selected during the initialization of the encrypted
partition. The new encrypted device will appear in
/dev as
/dev/device_name.bde:&prompt.root; ls /dev/ad*
/dev/ad0 /dev/ad0s1b /dev/ad0s1e /dev/ad4s1
/dev/ad0s1 /dev/ad0s1c /dev/ad0s1f /dev/ad4s1c
/dev/ad0s1a /dev/ad0s1d /dev/ad4 /dev/ad4s1c.bdeCreate a File System on the Encrypted
DeviceOnce the encrypted device has been attached to the
kernel, a file system can be created on the device. This
example creates a UFS file system with
soft updates enabled. Be sure to specify the partition
which has a
*.bde
extension:&prompt.root; newfs -U /dev/ad4s1c.bdeMount the Encrypted PartitionCreate a mount point and mount the encrypted file
system:&prompt.root; mkdir /private
&prompt.root; mount /dev/ad4s1c.bde /privateVerify That the Encrypted File System is
AvailableThe encrypted file system should now be visible and
available for use:&prompt.user; df -H
Filesystem Size Used Avail Capacity Mounted on
/dev/ad0s1a 1037M 72M 883M 8% /
/devfs 1.0K 1.0K 0B 100% /dev
/dev/ad0s1f 8.1G 55K 7.5G 0% /home
/dev/ad0s1e 1037M 1.1M 953M 0% /tmp
/dev/ad0s1d 6.1G 1.9G 3.7G 35% /usr
/dev/ad4s1c.bde 150G 4.1K 138G 0% /privateAfter each boot, any encrypted file systems must be
manually re-attached to the kernel, checked for errors, and
mounted, before the file systems can be used. To configure
these steps, add the following lines to
/etc/rc.conf:gbde_autoattach_all="YES"
gbde_devices="ad4s1c"
gbde_lockdir="/etc/gbde"This requires that the passphrase be entered at the
console at boot time. After typing the correct passphrase,
the encrypted partition will be mounted automatically.
Additional gbde boot options are
available and listed in &man.rc.conf.5;.sysinstall is incompatible
with gbde-encrypted devices. All
*.bde devices must be detached from the
kernel before starting sysinstall
or it will crash during its initial probing for devices. To
detach the encrypted device used in the example, use the
following command:&prompt.root; gbde detach /dev/ad4s1cDisk Encryption with geliDanielGerzoContributed by An alternative cryptographic GEOM class
is available using geli. This control
utility adds some features and uses a different scheme for
doing cryptographic work. It provides the following
features:Utilizes the &man.crypto.9; framework and
automatically uses cryptographic hardware when it is
available.Supports multiple cryptographic algorithms such as
AES, Blowfish, and
3DES.Allows the root partition to be encrypted. The
passphrase used to access the encrypted root partition
will be requested during system boot.Allows the use of two independent keys.It is fast as it performs simple sector-to-sector
encryption.Allows backup and restore of master keys. If a user
destroys their keys, it is still possible to get access to
the data by restoring keys from the backup.Allows a disk to attach with a random, one-time key
which is useful for swap partitions and temporary file
systems.More features and usage examples can be found in
&man.geli.8;.The following example describes how to generate a key file
which will be used as part of the master key for the encrypted
provider mounted under /private. The key
file will provide some random data used to encrypt the master
key. The master key will also be protected by a passphrase.
The provider's sector size will be 4kB. The example describes
how to attach to the geli provider, create
a file system on it, mount it, work with it, and finally, how
to detach it.Encrypting a Partition with
geliLoad geli SupportSupport for geli is available as a
loadable kernel module. To configure the system to
automatically load the module at boot time, add the
following line to
/boot/loader.conf:geom_eli_load="YES"To load the kernel module now:&prompt.root; kldload geom_eliFor a custom kernel, ensure the kernel configuration
file contains these lines:options GEOM_ELI
device cryptoGenerate the Master KeyThe following commands generate a master key
(/root/da2.key) that is protected
with a passphrase. The data source for the key file is
/dev/random and the sector size of
the provider (/dev/da2.eli) is 4kB as
a bigger sector size provides better performance:&prompt.root; dd if=/dev/random of=/root/da2.key bs=64 count=1
&prompt.root; geli init -s 4096 -K /root/da2.key /dev/da2
Enter new passphrase:
Reenter new passphrase:It is not mandatory to use both a passphrase and a key
file as either method of securing the master key can be
used in isolation.If the key file is given as -, standard
input will be used. For example, this command generates
three key files:&prompt.root; cat keyfile1 keyfile2 keyfile3 | geli init -K - /dev/da2Attach the Provider with the Generated KeyTo attach the provider, specify the key file, the name
of the disk, and the passphrase:&prompt.root; geli attach -k /root/da2.key /dev/da2
Enter passphrase:This creates a new device with an
.eli extension:&prompt.root; ls /dev/da2*
/dev/da2 /dev/da2.eliCreate the New File SystemNext, format the device with the
UFS file system and mount it on an
existing mount point:&prompt.root; dd if=/dev/random of=/dev/da2.eli bs=1m
&prompt.root; newfs /dev/da2.eli
&prompt.root; mount /dev/da2.eli /privateThe encrypted file system should now be available for
use:&prompt.root; df -H
Filesystem Size Used Avail Capacity Mounted on
/dev/ad0s1a 248M 89M 139M 38% /
/devfs 1.0K 1.0K 0B 100% /dev
/dev/ad0s1f 7.7G 2.3G 4.9G 32% /usr
/dev/ad0s1d 989M 1.5M 909M 0% /tmp
/dev/ad0s1e 3.9G 1.3G 2.3G 35% /var
/dev/da2.eli 150G 4.1K 138G 0% /privateOnce the work on the encrypted partition is done, and the
/private partition is no longer needed,
it is prudent to put the device into cold storage by
unmounting and detaching the geli encrypted
partition from the kernel:&prompt.root; umount /private
&prompt.root; geli detach da2.eliA rc.d script is provided to
simplify the mounting of geli-encrypted
devices at boot time. For this example, add these lines to
/etc/rc.conf:geli_devices="da2"
geli_da2_flags="-k /root/da2.key"This configures /dev/da2 as a
geli provider with a master key of
/root/da2.key. The system will
automatically detach the provider from the kernel before the
system shuts down. During the startup process, the script
will prompt for the passphrase before attaching the provider.
Other kernel messages might be shown before and after the
password prompt. If the boot process seems to stall, look
carefully for the password prompt among the other messages.
Once the correct passphrase is entered, the provider is
attached. The file system is then mounted, typically by an
entry in /etc/fstab. Refer to for instructions on how to
configure a file system to mount at boot time.Encrypting SwapChristianBruefferWritten by swapencryptingLike the encryption of disk partitions, encryption of swap
space is used to protect sensitive information. Consider an
application that deals with passwords. As long as these
passwords stay in physical memory, they are not written to disk
and will be cleared after a reboot. However, if &os; starts
swapping out memory pages to free space, the passwords may be
written to the disk unencrypted. Encrypting swap space can be a
solution for this scenario.This section demonstrates how to configure an encrypted
swap partition using &man.gbde.8; or &man.geli.8; encryption.
It assumes that
/dev/ada0s1b is the swap partition.Configuring Encrypted SwapSwap partitions are not encrypted by default and should be
cleared of any sensitive data before continuing. To overwrite
the current swap partition with random garbage, execute the
following command:&prompt.root; dd if=/dev/random of=/dev/ada0s1b bs=1mTo encrypt the swap partition using &man.gbde.8;, add the
.bde suffix to the swap line in
/etc/fstab:# Device Mountpoint FStype Options Dump Pass#
/dev/ada0s1b.bde none swap sw 0 0To instead encrypt the swap partition using &man.geli.8;,
use the
.eli suffix:# Device Mountpoint FStype Options Dump Pass#
/dev/ada0s1b.eli none swap sw 0 0By default, &man.geli.8; uses the AES
algorithm with a key length of 128 bits. Normally the default
settings will suffice. If desired, these defaults can be
altered in the options field in
/etc/fstab. The possible flags
are:aalgoData integrity verification algorithm used to ensure
that the encrypted data has not been tampered with. See
&man.geli.8; for a list of supported algorithms.ealgoEncryption algorithm used to protect the data. See
&man.geli.8; for a list of supported algorithms.keylenThe length of the key used for the encryption
algorithm. See &man.geli.8; for the key lengths that
are supported by each encryption algorithm.sectorsizeThe size of the blocks data is broken into before
it is encrypted. Larger sector sizes increase
performance at the cost of higher storage
overhead. The recommended size is 4096 bytes.This example configures an encryped swap partition using
the Blowfish algorithm with a key length of 128 bits and a
sectorsize of 4 kilobytes:# Device Mountpoint FStype Options Dump Pass#
/dev/ada0s1b.eli none swap sw,ealgo=blowfish,keylen=128,sectorsize=4096 0 0Encrypted Swap VerificationOnce the system has rebooted, proper operation of the
encrypted swap can be verified using
swapinfo.If &man.gbde.8; is being used:&prompt.user; swapinfo
Device 1K-blocks Used Avail Capacity
/dev/ada0s1b.bde 542720 0 542720 0%If &man.geli.8; is being used:&prompt.user; swapinfo
Device 1K-blocks Used Avail Capacity
/dev/ada0s1b.eli 542720 0 542720 0%Highly Available Storage
(HAST)DanielGerzoContributed by FreddieCashWith inputs from Pawel JakubDawidekMichael W.LucasViktorPeterssonHASThigh availabilityHigh availability is one of the main requirements in
serious business applications and highly-available storage is a
key component in such environments. In &os;, the Highly
Available STorage (HAST) framework allows
transparent storage of the same data across several physically
separated machines connected by a TCP/IP
network. HAST can be understood as a
network-based RAID1 (mirror), and is similar to the DRBD®
storage system used in the GNU/&linux; platform. In combination
with other high-availability features of &os; like
CARP, HAST makes it
possible to build a highly-available storage cluster that is
resistant to hardware failures.The following are the main features of
HAST:Can be used to mask I/O errors on
local hard drives.File system agnostic as it works with any file system
supported by &os;.Efficient and quick resynchronization as only the blocks
that were modified during the downtime of a node are
synchronized.Can be used in an already deployed environment to add
additional redundancy.Together with CARP,
Heartbeat, or other tools, it can
be used to build a robust and durable storage system.After reading this section, you will know:What HAST is, how it works, and
which features it provides.How to set up and use HAST on
&os;.How to integrate CARP and
&man.devd.8; to build a robust storage system.Before reading this section, you should:Understand &unix; and &os; basics ().Know how to configure network
interfaces and other core &os; subsystems ().Have a good understanding of &os;
networking ().The HAST project was sponsored by The
&os; Foundation with support from http://www.omc.net/
and http://www.transip.nl/.HAST OperationHAST provides synchronous block-level
replication between two physical machines: the
primary, also known as the
master node, and the
secondary, or slave
node. These two machines together are referred to as a
cluster.Since HAST works in a primary-secondary
configuration, it allows only one of the cluster nodes to be
active at any given time. The primary node, also called
active, is the one which will handle all
the I/O requests to
HAST-managed devices. The secondary node
is automatically synchronized from the primary node.The physical components of the HAST
system are the local disk on primary node, and the disk on the
remote, secondary node.HAST operates synchronously on a block
level, making it transparent to file systems and applications.
HAST provides regular GEOM providers in
/dev/hast/ for use by other tools or
applications. There is no difference between using
HAST-provided devices and raw disks or
partitions.Each write, delete, or flush operation is sent to both the
local disk and to the remote disk over
TCP/IP. Each read operation is served from
the local disk, unless the local disk is not up-to-date or an
I/O error occurs. In such cases, the read
operation is sent to the secondary node.HAST tries to provide fast failure
recovery. For this reason, it is important to reduce
synchronization time after a node's outage. To provide fast
synchronization, HAST manages an on-disk
bitmap of dirty extents and only synchronizes those during a
regular synchronization, with an exception of the initial
sync.There are many ways to handle synchronization.
HAST implements several replication modes
to handle different synchronization methods:memsync: This mode reports a
write operation as completed when the local write
operation is finished and when the remote node
acknowledges data arrival, but before actually storing the
data. The data on the remote node will be stored directly
after sending the acknowledgement. This mode is intended
to reduce latency, but still provides good reliability.
This mode is the default.fullsync: This mode reports a
write operation as completed when both the local write and
the remote write complete. This is the safest and the
slowest replication mode.async: This mode reports a write
operation as completed when the local write completes.
This is the fastest and the most dangerous replication
mode. It should only be used when replicating to a
distant node where latency is too high for other
modes.HAST ConfigurationThe HAST framework consists of several
components:The &man.hastd.8; daemon which provides data
synchronization. When this daemon is started, it will
automatically load geom_gate.ko.The userland management utility,
&man.hastctl.8;.The &man.hast.conf.5; configuration file. This file
must exist before starting
hastd.Users who prefer to statically build
GEOM_GATE support into the kernel should
add this line to the custom kernel configuration file, then
rebuild the kernel using the instructions in :options GEOM_GATEThe following example describes how to configure two nodes
in master-slave/primary-secondary operation using
HAST to replicate the data between the two.
The nodes will be called hasta, with an
IP address of
172.16.0.1, and hastb,
with an IP address of
172.16.0.2. Both nodes will have a
dedicated hard drive /dev/ad6 of the same
size for HAST operation. The
HAST pool, sometimes referred to as a
resource or the GEOM provider in /dev/hast/, will be called
test.Configuration of HAST is done using
/etc/hast.conf. This file should be
identical on both nodes. The simplest configuration
is:resource test {
on hasta {
local /dev/ad6
remote 172.16.0.2
}
on hastb {
local /dev/ad6
remote 172.16.0.1
}
}For more advanced configuration, refer to
&man.hast.conf.5;.It is also possible to use host names in the
remote statements if the hosts are
resolvable and defined either in
/etc/hosts or in the local
DNS.Once the configuration exists on both nodes, the
HAST pool can be created. Run these
commands on both nodes to place the initial metadata onto the
local disk and to start &man.hastd.8;:&prompt.root; hastctl create test
&prompt.root; service hastd onestartIt is not possible to use
GEOM
providers with an existing file system or to convert an
existing storage to a HAST-managed pool.
This procedure needs to store some metadata on the provider
and there will not be enough required space available on an
existing provider.A HAST node's primary or
secondary role is selected by an
administrator, or software like
Heartbeat, using &man.hastctl.8;.
On the primary node, hasta, issue this
command:&prompt.root; hastctl role primary testRun this command on the secondary node,
hastb:&prompt.root; hastctl role secondary testVerify the result by running hastctl on
each node:&prompt.root; hastctl status testCheck the status line in the output.
If it says degraded, something is wrong
with the configuration file. It should say
complete on each node, meaning that the
synchronization between the nodes has started. The
synchronization completes when hastctl
status reports 0 bytes of dirty
extents.The next step is to create a file system on the
GEOM provider and mount it. This must be
done on the primary node. Creating the
file system can take a few minutes, depending on the size of
the hard drive. This example creates a UFS
file system on /dev/hast/test:&prompt.root; newfs -U /dev/hast/test
&prompt.root; mkdir /hast/test
&prompt.root; mount /dev/hast/test/hast/testOnce the HAST framework is configured
properly, the final step is to make sure that
HAST is started automatically during
system boot. Add this line to
/etc/rc.conf:hastd_enable="YES"Failover ConfigurationThe goal of this example is to build a robust storage
system which is resistant to the failure of any given node.
If the primary node fails, the secondary node is there to
take over seamlessly, check and mount the file system, and
continue to work without missing a single bit of
data.To accomplish this task, the Common Address Redundancy
Protocol (CARP) is used to provide for
automatic failover at the IP layer.
CARP allows multiple hosts on the same
network segment to share an IP address.
Set up CARP on both nodes of the cluster
according to the documentation available in . In this example, each node will have
its own management IP address and a
shared IP address of
172.16.0.254. The primary
HAST node of the cluster must be the
master CARP node.The HAST pool created in the previous
section is now ready to be exported to the other hosts on
the network. This can be accomplished by exporting it
through NFS or
Samba, using the shared
IP address
172.16.0.254. The only problem
which remains unresolved is an automatic failover should the
primary node fail.In the event of CARP interfaces going
up or down, the &os; operating system generates a
&man.devd.8; event, making it possible to watch for state
changes on the CARP interfaces. A state
change on the CARP interface is an
indication that one of the nodes failed or came back online.
These state change events make it possible to run a script
which will automatically handle the HAST failover.To catch state changes on the
CARP interfaces, add this configuration
to /etc/devd.conf on each node:notify 30 {
match "system" "IFNET";
match "subsystem" "carp0";
match "type" "LINK_UP";
action "/usr/local/sbin/carp-hast-switch master";
};
notify 30 {
match "system" "IFNET";
match "subsystem" "carp0";
match "type" "LINK_DOWN";
action "/usr/local/sbin/carp-hast-switch slave";
};If the systems are running &os; 10 or higher,
replace carp0 with the name of the
CARP-configured interface.Restart &man.devd.8; on both nodes to put the new
configuration into effect:&prompt.root; service devd restartWhen the specified interface state changes by going up
or down , the system generates a notification, allowing the
&man.devd.8; subsystem to run the specified automatic
failover script,
/usr/local/sbin/carp-hast-switch.
For further clarification about this configuration, refer to
&man.devd.conf.5;.Here is an example of an automated failover
script:#!/bin/sh
# Original script by Freddie Cash <fjwcash@gmail.com>
# Modified by Michael W. Lucas <mwlucas@BlackHelicopters.org>
# and Viktor Petersson <vpetersson@wireload.net>
# The names of the HAST resources, as listed in /etc/hast.conf
resources="test"
# delay in mounting HAST resource after becoming master
# make your best guess
delay=3
# logging
log="local0.debug"
name="carp-hast"
# end of user configurable stuff
case "$1" in
master)
logger -p $log -t $name "Switching to primary provider for ${resources}."
sleep ${delay}
# Wait for any "hastd secondary" processes to stop
for disk in ${resources}; do
while $( pgrep -lf "hastd: ${disk} \(secondary\)" > /dev/null 2>&1 ); do
sleep 1
done
# Switch role for each disk
hastctl role primary ${disk}
if [ $? -ne 0 ]; then
logger -p $log -t $name "Unable to change role to primary for resource ${disk}."
exit 1
fi
done
# Wait for the /dev/hast/* devices to appear
for disk in ${resources}; do
for I in $( jot 60 ); do
[ -c "/dev/hast/${disk}" ] && break
sleep 0.5
done
if [ ! -c "/dev/hast/${disk}" ]; then
logger -p $log -t $name "GEOM provider /dev/hast/${disk} did not appear."
exit 1
fi
done
logger -p $log -t $name "Role for HAST resources ${resources} switched to primary."
logger -p $log -t $name "Mounting disks."
for disk in ${resources}; do
mkdir -p /hast/${disk}
fsck -p -y -t ufs /dev/hast/${disk}
mount /dev/hast/${disk} /hast/${disk}
done
;;
slave)
logger -p $log -t $name "Switching to secondary provider for ${resources}."
# Switch roles for the HAST resources
for disk in ${resources}; do
if ! mount | grep -q "^/dev/hast/${disk} on "
then
else
umount -f /hast/${disk}
fi
sleep $delay
hastctl role secondary ${disk} 2>&1
if [ $? -ne 0 ]; then
logger -p $log -t $name "Unable to switch role to secondary for resource ${disk}."
exit 1
fi
logger -p $log -t $name "Role switched to secondary for resource ${disk}."
done
;;
esacIn a nutshell, the script takes these actions when a
node becomes master:Promotes the HAST pool to
primary on the other node.Checks the file system under the
HAST pool.Mounts the pool.When a node becomes secondary:Unmounts the HAST pool.Degrades the HAST pool to
secondary.This is just an example script which serves as a proof
of concept. It does not handle all the possible scenarios
and can be extended or altered in any way, for example, to
start or stop required services.For this example, a standard UFS
file system was used. To reduce the time needed for
recovery, a journal-enabled UFS or
ZFS file system can be used
instead.More detailed information with additional examples can
be found at http://wiki.FreeBSD.org/HAST.TroubleshootingHAST should generally work without
issues. However, as with any other software product, there
may be times when it does not work as supposed. The sources
of the problems may be different, but the rule of thumb is to
ensure that the time is synchronized between the nodes of the
cluster.When troubleshooting HAST, the
debugging level of &man.hastd.8; should be increased by
starting hastd with -d.
This argument may be specified multiple times to further
increase the debugging level. Consider also using
-F, which starts hastd
in the foreground.Recovering from the Split-brain ConditionSplit-brain occurs when the nodes
of the cluster are unable to communicate with each other,
and both are configured as primary. This is a dangerous
condition because it allows both nodes to make incompatible
changes to the data. This problem must be corrected
manually by the system administrator.The administrator must either decide which node has more
important changes, or perform the merge manually. Then, let
HAST perform full synchronization of the
node which has the broken data. To do this, issue these
commands on the node which needs to be
resynchronized:&prompt.root; hastctl role init test
&prompt.root; hastctl create test
&prompt.root; hastctl role secondary test
Index: head/en_US.ISO8859-1/books/handbook/mail/chapter.xml
===================================================================
--- head/en_US.ISO8859-1/books/handbook/mail/chapter.xml (revision 50807)
+++ head/en_US.ISO8859-1/books/handbook/mail/chapter.xml (revision 50808)
@@ -1,1951 +1,1951 @@
Electronic MailBillLloydOriginal
work by JimMockRewritten
by SynopsisemailElectronic Mail, better known as email, is
one of the most widely used forms of communication today. This
chapter provides a basic introduction to running a mail server
on &os;, as well as an introduction to sending and receiving
email using &os;. For more complete coverage of this subject,
refer to the books listed in .After reading this chapter, you will know:Which software components are involved in sending and
receiving electronic mail.Where basic Sendmail
configuration files are located in &os;.The difference between remote and local
mailboxes.How to block spammers from illegally using a mail server
as a relay.How to install and configure an alternate Mail Transfer
Agent, replacing
Sendmail.How to troubleshoot common mail server problems.How to set up the system to send mail only.How to use mail with a dialup connection.How to configure SMTP authentication for added
security.How to install and use a Mail User Agent, such as
mutt, to send and receive
email.How to download mail from a remote
POP or IMAP
server.How to automatically apply filters and rules to incoming
email.Before reading this chapter, you should:Properly set up a network connection ().Properly set up the DNS information
for a mail host ().Know how to install additional third-party software
().Mail ComponentsPOPIMAPDNSmail server daemonsSendmailmail server daemonsPostfixmail server daemonsqmailmail server daemonsEximemailreceivingMX recordmail hostThere are five major parts involved in an email exchange:
the Mail User Agent (MUA), the Mail Transfer
Agent (MTA), a mail host, a remote or local
mailbox, and DNS. This section provides an
overview of these components.Mail User Agent (MUA)The Mail User Agent (MUA) is an
application which is used to compose, send, and receive
emails. This application can be a command line program,
such as the built-in mail utility or a
third-party application from the Ports Collection, such as
mutt,
alpine, or
elm. Dozens of graphical
programs are also available in the Ports Collection,
including Claws Mail,
Evolution, and
Thunderbird. Some
organizations provide a web mail program which can be
accessed through a web browser. More information about
installing and using a MUA on &os; can
be found in .Mail Transfer Agent (MTA)The Mail Transfer Agent (MTA) is
responsible for receiving incoming mail and delivering
outgoing mail. &os; ships with
Sendmail as the default
MTA, but it also supports numerous
other mail server daemons, including
Exim,
Postfix, and
qmail.
Sendmail configuration is
described in . If another
MTA is installed using the Ports
Collection, refer to its post-installation message for
&os;-specific configuration details and the application's
website for more general configuration
instructions.Mail Host and MailboxesThe mail host is a server that is responsible for
delivering and receiving mail for a host or a network.
The mail host collects all mail sent to the domain and
stores it either in the default mbox
or the alternative Maildir format, depending on the
configuration. Once mail has been stored, it may either
be read locally using a MUA or remotely
accessed and collected using protocols such as
POP or IMAP. If
mail is read locally, a POP or
IMAP server does not need to be
installed.To access mailboxes remotely, a POP
or IMAP server is required as these
protocols allow users to connect to their mailboxes from
remote locations. IMAP offers several
advantages over POP. These include the
ability to store a copy of messages on a remote server
after they are downloaded and concurrent updates.
IMAP can be useful over low-speed links
as it allows users to fetch the structure of messages
without downloading them. It can also perform tasks such
as searching on the server in order to minimize data
transfer between clients and servers.Several POP and
IMAP servers are available in the Ports
Collection. These include
mail/qpopper,
mail/imap-uw,
mail/courier-imap, and
mail/dovecot2.It should be noted that both POP
and IMAP transmit information,
including username and password credentials, in
clear-text. To secure the transmission of information
across these protocols, consider tunneling sessions over
&man.ssh.1; ()
or using SSL ().Domain Name System (DNS)The Domain Name System (DNS) and
its daemon named play a large role in
the delivery of email. In order to deliver mail from one
site to another, the MTA will look up
the remote site in DNS to determine
which host will receive mail for the destination. This
process also occurs when mail is sent from a remote host
to the MTA.In addition to mapping hostnames to
IP addresses, DNS is
responsible for storing information specific to mail
delivery, known as Mail eXchanger
MX records. The MX
record specifies which hosts will receive mail for a
particular domain.To view the MX records for a
domain, specify the type of record. Refer to
&man.host.1;, for more details about this command:&prompt.user; host -t mx FreeBSD.org
FreeBSD.org mail is handled by 10 mx1.FreeBSD.orgRefer to for more
information about DNS and its
configuration.Sendmail Configuration
FilesChristopherShumwayContributed by SendmailSendmail is the default
MTA installed with &os;. It accepts mail
from MUAs and delivers it to the appropriate
mail host, as defined by its configuration.
Sendmail can also accept network
connections and deliver mail to local mailboxes or to another
program.The configuration files for
Sendmail are located in
/etc/mail. This section describes these
files in more detail./etc/mail/access/etc/mail/aliases/etc/mail/local-host-names/etc/mail/mailer.conf/etc/mail/mailertable/etc/mail/sendmail.cf/etc/mail/virtusertable/etc/mail/accessThis access database file defines which hosts or
IP addresses have access to the local
mail server and what kind of access they have. Hosts
listed as , which is the default
option, are allowed to send mail to this host as long as
the mail's final destination is the local machine. Hosts
listed as are rejected for all
mail connections. Hosts listed as
are allowed to send mail for any destination using this
mail server. Hosts listed as will
have their mail returned with the specified mail error.
If a host is listed as ,
Sendmail will abort the current
search for this entry without accepting or rejecting the
mail. Hosts listed as will
have their messages held and will receive the specified
text as the reason for the hold.Examples of using these options for both
IPv4 and IPv6
addresses can be found in the &os; sample configuration,
/etc/mail/access.sample:
- # $FreeBSD$
+ # $FreeBSD$
#
# Mail relay access control list. Default is to reject mail unless the
# destination is local, or listed in /etc/mail/local-host-names
#
## Examples (commented out for safety)
#From:cyberspammer.com ERROR:"550 We don't accept mail from spammers"
#From:okay.cyberspammer.com OK
#Connect:sendmail.org RELAY
#To:sendmail.org RELAY
#Connect:128.32 RELAY
#Connect:128.32.2 SKIP
#Connect:IPv6:1:2:3:4:5:6:7 RELAY
#Connect:suspicious.example.com QUARANTINE:Mail from suspicious host
#Connect:[127.0.0.3] OK
#Connect:[IPv6:1:2:3:4:5:6:7:8] OKTo configure the access database, use the format shown
in the sample to make entries in
/etc/mail/access, but do not put a
comment symbol (#) in front of the
entries. Create an entry for each host or network whose
access should be configured. Mail senders that match the
left side of the table are affected by the action on the
right side of the table.Whenever this file is updated, update its database and
restart Sendmail:&prompt.root; makemap hash /etc/mail/access < /etc/mail/access
&prompt.root; service sendmail restart/etc/mail/aliasesThis database file contains a list of virtual
mailboxes that are expanded to users, files, programs, or
other aliases. Here are a few entries to illustrate the
file format:root: localuser
ftp-bugs: joe,eric,paul
bit.bucket: /dev/null
procmail: "|/usr/local/bin/procmail"The mailbox name on the left side of the colon is
expanded to the target(s) on the right. The first entry
expands the root
mailbox to the localuser mailbox, which
is then looked up in the
/etc/mail/aliases database. If no
match is found, the message is delivered to localuser. The second
entry shows a mail list. Mail to ftp-bugs is expanded to
the three local mailboxes joe, eric, and paul. A remote mailbox
could be specified as
user@example.com. The third
entry shows how to write mail to a file, in this case
/dev/null. The last entry
demonstrates how to send mail to a program,
/usr/local/bin/procmail, through a
&unix; pipe. Refer to &man.aliases.5; for more
information about the format of this file.Whenever this file is updated, run
newaliases to update and initialize the
aliases database./etc/mail/sendmail.cfThis is the master configuration file for
Sendmail. It controls the
overall behavior of Sendmail,
including everything from rewriting email addresses to
printing rejection messages to remote mail servers.
Accordingly, this configuration file is quite complex.
Fortunately, this file rarely needs to be changed for
standard mail servers.The master Sendmail
configuration file can be built from &man.m4.1; macros
that define the features and behavior of
Sendmail. Refer to
/usr/src/contrib/sendmail/cf/README
for some of the details.Whenever changes to this file are made,
Sendmail needs to be restarted
for the changes to take effect./etc/mail/virtusertableThis database file maps mail addresses for virtual
domains and users to real mailboxes. These mailboxes can
be local, remote, aliases defined in
/etc/mail/aliases, or files. This
allows multiple virtual domains to be hosted on one
machine.&os; provides a sample configuration file in
/etc/mail/virtusertable.sample to
further demonstrate its format. The following example
demonstrates how to create custom entries using that
format:root@example.com root
postmaster@example.com postmaster@noc.example.net
@example.com joeThis file is processed in a first match order. When
an email address matches the address on the left, it is
mapped to the local mailbox listed on the right. The
format of the first entry in this example maps a specific
email address to a local mailbox, whereas the format of
the second entry maps a specific email address to a remote
mailbox. Finally, any email address from
example.com which has not matched any
of the previous entries will match the last mapping and be
sent to the local mailbox joe. When
creating custom entries, use this format and add them to
/etc/mail/virtusertable. Whenever
this file is edited, update its database and restart
Sendmail:&prompt.root; makemap hash /etc/mail/virtusertable < /etc/mail/virtusertable
&prompt.root; service sendmail restart/etc/mail/relay-domainsIn a default &os; installation,
Sendmail is configured to only
send mail from the host it is running on. For example, if
a POP server is available, users will
be able to check mail from remote locations but they will
not be able to send outgoing emails from outside
locations. Typically, a few moments after the attempt, an
email will be sent from MAILER-DAEMON
with a 5.7 Relaying Denied
message.The most straightforward solution is to add the
ISP's FQDN to
/etc/mail/relay-domains. If multiple
addresses are needed, add them one per
line:your.isp.example.com
other.isp.example.net
users-isp.example.org
www.example.orgAfter creating or editing this file, restart
Sendmail with
service sendmail restart.Now any mail sent through the system by any host in
this list, provided the user has an account on the system,
will succeed. This allows users to send mail from the
system remotely without opening the system up to relaying
SPAM from the Internet.Changing the Mail Transfer AgentAndrewBoothmanWritten by GregoryNeil ShapiroInformation taken from emails written by emailchange mta&os; comes with Sendmail already
installed as the MTA which is in charge of
outgoing and incoming mail. However, the system administrator
can change the system's MTA. A wide choice
of alternative MTAs is available from the
mail category of the &os; Ports
Collection.Once a new MTA is installed, configure
and test the new software before replacing
Sendmail. Refer to the documentation
of the new MTA for information on how to
configure the software.Once the new MTA is working, use the
instructions in this section to disable
Sendmail and configure &os; to use
the replacement MTA.Disable SendmailIf Sendmail's outgoing mail
service is disabled, it is important that it is replaced
with an alternative mail delivery system. Otherwise, system
functions such as &man.periodic.8; will be unable to deliver
their results by email. Many parts of the system expect a
functional MTA. If applications continue
to use Sendmail's binaries to try
to send email after they are disabled, mail could go into an
inactive Sendmail queue and
never be delivered.In order to completely disable
Sendmail, add or edit the following
lines in /etc/rc.conf:sendmail_enable="NO"
sendmail_submit_enable="NO"
sendmail_outbound_enable="NO"
sendmail_msp_queue_enable="NO"To only disable Sendmail's
incoming mail service, use only this entry in
/etc/rc.conf:sendmail_enable="NO"More information on Sendmail's
startup options is available in &man.rc.sendmail.8;.Replace the Default MTAWhen a new MTA is installed using the
Ports Collection, its startup script is also installed and
startup instructions are mentioned in its package message.
Before starting the new MTA, stop the
running Sendmail processes. This
example stops all of these services, then starts the
Postfix service:&prompt.root; service sendmail stop
&prompt.root; service postfix startTo start the replacement MTA at system
boot, add its configuration line to
/etc/rc.conf. This entry enables the
Postfix MTA:postfix_enable="YES"Some extra configuration is needed as
Sendmail is so ubiquitous that some
software assumes it is already installed and configured.
Check /etc/periodic.conf and make sure
that these values are set to NO. If this
file does not exist, create it with these entries:daily_clean_hoststat_enable="NO"
daily_status_mail_rejects_enable="NO"
daily_status_include_submit_mailq="NO"
daily_submit_queuerun="NO"Some alternative MTAs provide their own
compatible implementations of the
Sendmail command-line interface in
order to facilitate using them as drop-in replacements for
Sendmail. However, some
MUAs may try to execute standard
Sendmail binaries instead of the
new MTA's binaries. &os; uses
/etc/mail/mailer.conf to map the expected
Sendmail binaries to the location
of the new binaries. More information about this mapping can
be found in &man.mailwrapper.8;.The default /etc/mail/mailer.conf
looks like this:
- # $FreeBSD$
+ # $FreeBSD$
#
# Execute the "real" sendmail program, named /usr/libexec/sendmail/sendmail
#
sendmail /usr/libexec/sendmail/sendmail
send-mail /usr/libexec/sendmail/sendmail
mailq /usr/libexec/sendmail/sendmail
newaliases /usr/libexec/sendmail/sendmail
hoststat /usr/libexec/sendmail/sendmail
purgestat /usr/libexec/sendmail/sendmailWhen any of the commands listed on the left are run, the
system actually executes the associated command shown on the
right. This system makes it easy to change what binaries are
executed when these default binaries are invoked.Some MTAs, when installed using the
Ports Collection, will prompt to update this file for the new
binaries. For example, Postfix
will update the file like this:#
# Execute the Postfix sendmail program, named /usr/local/sbin/sendmail
#
sendmail /usr/local/sbin/sendmail
send-mail /usr/local/sbin/sendmail
mailq /usr/local/sbin/sendmail
newaliases /usr/local/sbin/sendmailIf the installation of the MTA does
not automatically update
/etc/mail/mailer.conf, edit this file in
a text editor so that it points to the new binaries. This
example points to the binaries installed by
mail/ssmtp:sendmail /usr/local/sbin/ssmtp
send-mail /usr/local/sbin/ssmtp
mailq /usr/local/sbin/ssmtp
newaliases /usr/local/sbin/ssmtp
hoststat /usr/bin/true
purgestat /usr/bin/trueOnce everything is configured, it is recommended to reboot
the system. Rebooting provides the opportunity to ensure that
the system is correctly configured to start the new
MTA automatically on boot.TroubleshootingemailtroubleshootingWhy do I have to use the FQDN for hosts on my
site?The host may actually be in a different domain. For
example, in order for a host in foo.bar.edu to reach a
host called mumble in the
bar.edu
domain, refer to it by the Fully-Qualified Domain Name
FQDN, mumble.bar.edu,
instead of just mumble.This is because the version of
BINDBIND which ships with &os;
no longer provides default abbreviations for non-FQDNs
other than the local domain. An unqualified host such as
mumble must either be found as
mumble.foo.bar.edu, or
it will be searched for in the root domain.In older versions of BIND,
the search continued across mumble.bar.edu, and
mumble.edu.
RFC 1535 details why this is considered bad practice or
even a security hole.As a good workaround, place the line:search foo.bar.edu bar.eduinstead of the previous:domain foo.bar.eduinto /etc/resolv.conf. However,
make sure that the search order does not go beyond the
boundary between local and public
administration, as RFC 1535 calls it.How can I run a mail server on a dial-up PPP
host?Connect to a &os; mail gateway on the LAN. The PPP
connection is non-dedicated.One way to do this is to get a full-time Internet
server to provide secondary
MX
MX record
services for the domain. In this example, the domain is
example.com
and the ISP has configured
example.net
to provide secondary MX services to the
domain:example.com. MX 10 example.com.
MX 20 example.net.Only one host should be specified as the final
recipient. For Sendmail, add
Cw example.com in
/etc/mail/sendmail.cf on example.com.When the sending MTA attempts
to deliver mail, it will try to connect to the system,
example.com,
over the PPP link. This will time out if the destination
is offline. The MTA will automatically
deliver it to the secondary MX site at
the Internet Service Provider (ISP),
example.net.
The secondary MX site will periodically
try to connect to the primary MX host,
example.com.Use something like this as a login script:#!/bin/sh
# Put me in /usr/local/bin/pppmyisp
( sleep 60 ; /usr/sbin/sendmail -q ) &
/usr/sbin/ppp -direct pppmyispWhen creating a separate login script for users,
instead use sendmail -qRexample.com in
the script above. This will force all mail in the queue
for
example.com
to be processed immediately.A further refinement of the situation can be seen from
this example from the &a.isp;:> we provide the secondary MX for a customer. The customer connects to
> our services several times a day automatically to get the mails to
> his primary MX (We do not call his site when a mail for his domains
> arrived). Our sendmail sends the mailqueue every 30 minutes. At the
> moment he has to stay 30 minutes online to be sure that all mail is
> gone to the primary MX.
>
> Is there a command that would initiate sendmail to send all the mails
> now? The user has not root-privileges on our machine of course.
In the privacy flags section of sendmail.cf, there is a
definition Opgoaway,restrictqrun
Remove restrictqrun to allow non-root users to start the queue processing.
You might also like to rearrange the MXs. We are the 1st MX for our
customers like this, and we have defined:
# If we are the best MX for a host, try directly instead of generating
# local config error.
OwTrue
That way a remote site will deliver straight to you, without trying
the customer connection. You then send to your customer. Only works for
hosts, so you need to get your customer to name their mail
machine customer.com as well as
hostname.customer.com in the DNS. Just put an A record in
the DNS for customer.com.Advanced TopicsThis section covers more involved topics such as mail
configuration and setting up mail for an entire domain.Basic ConfigurationemailconfigurationOut of the box, one can send email to external hosts as
long as /etc/resolv.conf is configured or
the network has access to a configured DNS
server. To have email delivered to the MTA
on the &os; host, do one of the following:Run a DNS server for the
domain.Get mail delivered directly to the
FQDN for the machine.SMTPIn order to have mail delivered directly to a host, it
must have a permanent static IP address, not a dynamic IP
address. If the system is behind a firewall, it must be
configured to allow SMTP traffic. To receive mail directly at
a host, one of these two must be configured:Make sure that the lowest-numbered
MXMX
record record in
DNS points to the host's static IP
address.Make sure there is no MX entry in
the DNS for the host.Either of the above will allow mail to be received
directly at the host.Try this:&prompt.root; hostname
example.FreeBSD.org
&prompt.root; host example.FreeBSD.org
example.FreeBSD.org has address 204.216.27.XXIn this example, mail sent directly to
yourlogin@example.FreeBSD.org
should work without problems, assuming
Sendmail is running correctly on
example.FreeBSD.org.For this example:&prompt.root; host example.FreeBSD.org
example.FreeBSD.org has address 204.216.27.XX
example.FreeBSD.org mail is handled (pri=10) by nevdull.FreeBSD.orgAll mail sent to example.FreeBSD.org will
be collected on hub under the same
username instead of being sent directly to your host.The above information is handled by the
DNS server. The DNS
record that carries mail routing information is the
MX entry. If no MX
record exists, mail will be delivered directly to the host by
way of its IP address.The MX entry for freefall.FreeBSD.org at
one time looked like this:freefall MX 30 mail.crl.net
freefall MX 40 agora.rdrop.com
freefall MX 10 freefall.FreeBSD.org
freefall MX 20 who.cdrom.comfreefall had many
MX entries. The lowest
MX number is the host that receives mail
directly, if available. If it is not accessible for some
reason, the next lower-numbered host will accept messages
temporarily, and pass it along when a lower-numbered host
becomes available.Alternate MX sites should have separate
Internet connections in order to be most useful. Your
ISP can provide this service.Mail for a DomainWhen configuring a MTA for a network,
any mail sent to hosts in its domain should be diverted to the
MTA so that users can receive their mail on
the master mail server.DNSTo make life easiest, a user account with the same
username should exist on both the
MTA and the system with the
MUA. Use &man.adduser.8; to create the
user accounts.The MTA must be the designated mail
exchanger for each workstation on the network. This is done
in theDNS configuration with an
MX record:example.FreeBSD.org A 204.216.27.XX ; Workstation
MX 10 nevdull.FreeBSD.org ; MailhostThis will redirect mail for the workstation to the
MTA no matter where the A record points.
The mail is sent to the MX host.This must be configured on a DNS
server. If the network does not run its own
DNS server, talk to the
ISP or DNS
provider.The following is an example of virtual email hosting.
Consider a customer with the domain customer1.org, where all
the mail for customer1.org should be
sent to mail.myhost.com. The
DNS entry should look like this:customer1.org MX 10 mail.myhost.comAn A> record is
not needed for customer1.org in order to
only handle email for that domain. However, running
ping against customer1.org will not
work unless an A record exists for
it.Tell the MTA which domains and/or
hostnames it should accept mail for. Either of the following
will work for Sendmail:Add the hosts to
/etc/mail/local-host-names when
using the FEATURE(use_cw_file).Add a Cwyour.host.com line to
/etc/sendmail.cf.Setting Up to Send OnlyBillMoranContributed by There are many instances where one may only want to send
mail through a relay. Some examples are:The computer is a desktop machine that needs to use
programs such as &man.send-pr.1;, using the
ISP's mail relay.The computer is a server that does not handle mail
locally, but needs to pass off all mail to a relay for
processing.While any MTA is capable of filling
this particular niche, it can be difficult to properly configure
a full-featured MTA just to handle offloading
mail. Programs such as Sendmail and
Postfix are overkill for this
use.Additionally, a typical Internet access service agreement
may forbid one from running a mail server.The easiest way to fulfill those needs is to install the
mail/ssmtp port:&prompt.root; cd /usr/ports/mail/ssmtp
&prompt.root; make install replace cleanOnce installed, mail/ssmtp can be
configured with
/usr/local/etc/ssmtp/ssmtp.conf:root=yourrealemail@example.com
mailhub=mail.example.com
rewriteDomain=example.com
hostname=_HOSTNAME_Use the real email address for root. Enter the
ISP's outgoing mail relay in place of
mail.example.com.
Some ISPs call this the outgoing mail
server or SMTP server.Make sure to disable Sendmail,
including the outgoing mail service. See for details.mail/ssmtp has some other options
available. Refer to the examples in
/usr/local/etc/ssmtp or the manual page
of ssmtp for more information.Setting up ssmtp in this manner
allows any software on the computer that needs to send mail to
function properly, while not violating the
ISP's usage policy or allowing the computer
to be hijacked for spamming.Using Mail with a Dialup ConnectionWhen using a static IP address, one should not need to
adjust the default configuration. Set the hostname to the
assigned Internet name and Sendmail
will do the rest.When using a dynamically assigned IP address and a dialup
PPP connection to the Internet, one usually has a mailbox on the
ISP's mail server. In this example, the
ISP's domain is example.net, the user name
is user, the hostname
is bsd.home, and
the ISP has allowed relay.example.net as a mail
relay.In order to retrieve mail from the ISP's
mailbox, install a retrieval agent from the Ports Collection.
mail/fetchmail is a good choice as it
supports many different protocols. Usually, the
ISP will provide POP.
When using user PPP, email can be
automatically fetched when an Internet connection is established
with the following entry in
/etc/ppp/ppp.linkup:MYADDR:
!bg su user -c fetchmailWhen using Sendmail to deliver
mail to non-local accounts, configure
Sendmail to process the mail queue as
soon as the Internet connection is established. To do this, add
this line after the above fetchmail entry in
/etc/ppp/ppp.linkup: !bg su user -c "sendmail -q"In this example, there is an account for
user on bsd.home. In the home
directory of user on
bsd.home, create a
.fetchmailrc which contains this
line:poll example.net protocol pop3 fetchall pass MySecretThis file should not be readable by anyone except
user as it contains
the password MySecret.In order to send mail with the correct
from: header, configure
Sendmail to use
user@example.net rather than user@bsd.home and to send all mail via
relay.example.net,
allowing quicker mail transmission.The following .mc should
suffice:VERSIONID(`bsd.home.mc version 1.0')
OSTYPE(bsd4.4)dnl
FEATURE(nouucp)dnl
MAILER(local)dnl
MAILER(smtp)dnl
Cwlocalhost
Cwbsd.home
MASQUERADE_AS(`example.net')dnl
FEATURE(allmasquerade)dnl
FEATURE(masquerade_envelope)dnl
FEATURE(nocanonify)dnl
FEATURE(nodns)dnl
define(`SMART_HOST', `relay.example.net')
Dmbsd.home
define(`confDOMAIN_NAME',`bsd.home')dnl
define(`confDELIVERY_MODE',`deferred')dnlRefer to the previous section for details of how to convert
this file into the sendmail.cf format. Do
not forget to restart Sendmail after
updating sendmail.cf.SMTP AuthenticationJamesGorhamWritten by Configuring SMTP authentication on the
MTA provides a number of benefits.
SMTP authentication adds a layer
of security to Sendmail, and provides
mobile users who switch hosts the ability to use the same
MTA without the need to reconfigure their
mail client's settings each time.Install security/cyrus-sasl2
from the Ports Collection. This port supports a number of
compile-time options. For the SMTP authentication method
demonstrated in this example, make sure that
is not disabled.After installing
security/cyrus-sasl2, edit
/usr/local/lib/sasl2/Sendmail.conf,
or create it if it does not exist, and add the following
line:pwcheck_method: saslauthdNext, install
security/cyrus-sasl2-saslauthd and add
the following line to
/etc/rc.conf:saslauthd_enable="YES"Finally, start the saslauthd daemon:&prompt.root; service saslauthd startThis daemon serves as a broker for
Sendmail to authenticate against
the &os; &man.passwd.5; database. This saves the trouble of
creating a new set of usernames and passwords for each user
that needs to use SMTP authentication,
and keeps the login and mail password the same.Next, edit /etc/make.conf and add
the following lines:SENDMAIL_CFLAGS=-I/usr/local/include/sasl -DSASL
SENDMAIL_LDFLAGS=-L/usr/local/lib
SENDMAIL_LDADD=-lsasl2These lines provide Sendmail
the proper configuration options for linking to
cyrus-sasl2 at compile time. Make sure
that cyrus-sasl2 has been installed
before recompiling
Sendmail.Recompile Sendmail by
executing the following commands:&prompt.root; cd /usr/src/lib/libsmutil
&prompt.root; make cleandir && make obj && make
&prompt.root; cd /usr/src/lib/libsm
&prompt.root; make cleandir && make obj && make
&prompt.root; cd /usr/src/usr.sbin/sendmail
&prompt.root; make cleandir && make obj && make && make installThis compile should not have any problems if
/usr/src has not changed extensively
and the shared libraries it needs are available.After Sendmail has been
compiled and reinstalled, edit
/etc/mail/freebsd.mc or the local
.mc. Many administrators choose
to use the output from &man.hostname.1; as the name of
.mc for uniqueness. Add these
lines:dnl set SASL options
TRUST_AUTH_MECH(`GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN')dnl
define(`confAUTH_MECHANISMS', `GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN')dnlThese options configure the different methods available
to Sendmail for authenticating
users. To use a method other than
pwcheck, refer to the
Sendmail documentation.Finally, run &man.make.1; while in
/etc/mail. That will run the new
.mc and create a
.cf named either
freebsd.cf or the name used for the
local .mc. Then, run make
install restart, which will copy the file to
sendmail.cf, and properly restart
Sendmail. For more information
about this process, refer to
/etc/mail/Makefile.To test the configuration, use a MUA to
send a test message. For further investigation, set the
of Sendmail
to 13 and watch
/var/log/maillog for any errors.For more information, refer to
SMTP authentication.Mail User AgentsMarcSilverContributed by Mail User AgentsA MUA is an application that is used to
send and receive email. As email evolves and
becomes more complex, MUAs are becoming
increasingly powerful and provide users increased functionality
and flexibility. The mail category of the
&os; Ports Collection contains numerous MUAs.
These include graphical email clients such as
Evolution or
Balsa and console based clients such
as mutt or
alpine.mail&man.mail.1; is the default
MUA installed with &os;. It is a console
based MUA that offers the basic
functionality required to send and receive text-based email.
It provides limited attachment support and can only access
local mailboxes.Although mail does not natively support
interaction with POP or
IMAP servers, these mailboxes may be
downloaded to a local mbox using an
application such as
fetchmail.In order to send and receive email, run
mail:&prompt.user; mailThe contents of the user's mailbox in
/var/mail are automatically read by
mail. Should the mailbox be empty, the
utility exits with a message indicating that no mail could
be found. If mail exists, the application interface starts,
and a list of messages will be displayed. Messages are
automatically numbered, as can be seen in the following
example:Mail version 8.1 6/6/93. Type ? for help.
"/var/mail/marcs": 3 messages 3 new
>N 1 root@localhost Mon Mar 8 14:05 14/510 "test"
N 2 root@localhost Mon Mar 8 14:05 14/509 "user account"
N 3 root@localhost Mon Mar 8 14:05 14/509 "sample"Messages can now be read by typing t
followed by the message number. This example reads the first
email:& t 1
Message 1:
From root@localhost Mon Mar 8 14:05:52 2004
X-Original-To: marcs@localhost
Delivered-To: marcs@localhost
To: marcs@localhost
Subject: test
Date: Mon, 8 Mar 2004 14:05:52 +0200 (SAST)
From: root@localhost (Charlie Root)
This is a test message, please reply if you receive it.As seen in this example, the message will be displayed
with full headers. To display the list of messages again,
press h.If the email requires a reply, press either
R or rmail keys. R instructs
mail to reply only to the sender of the
email, while r replies to all other
recipients of the message. These commands can be suffixed
with the mail number of the message to reply to. After typing
the response, the end of the message should be marked by a
single . on its own line. An example can be
seen below:& R 1
To: root@localhost
Subject: Re: test
Thank you, I did get your email.
.
EOTIn order to send a new email, press m,
followed by the recipient email address. Multiple recipients
may be specified by separating each address with the
, delimiter. The subject of the message may
then be entered, followed by the message contents. The end of
the message should be specified by putting a single
. on its own line.& mail root@localhost
Subject: I mastered mail
Now I can send and receive email using mail ... :)
.
EOTWhile using mail, press
? to display help at any time. Refer to
&man.mail.1; for more help on how to use
mail.&man.mail.1; was not designed to handle attachments and
thus deals with them poorly. Newer MUAs
handle attachments in a more intelligent way. Users who
prefer to use mail may find the
converters/mpack port to be of
considerable use.muttmutt is a powerful
MUA, with many features, including:The ability to thread messages.PGP support for digital signing and encryption of
email.MIME support.Maildir support.Highly customizable.Refer to http://www.mutt.org
for more information on
mutt.mutt may be installed using the
mail/mutt port. After the port has been
installed, mutt can be started by
issuing the following command:&prompt.user; muttmutt will automatically read
and display the contents of the user mailbox in
/var/mail. If no mails are found,
mutt will wait for commands from
the user. The example below shows
mutt displaying a list of
messages:To read an email, select it using the cursor keys and
press Enter. An example of
mutt displaying email can be seen
below:Similar to &man.mail.1;, mutt
can be used to reply only to the sender of the message as well
as to all recipients. To reply only to the sender of the
email, press r. To send a group reply
to the original sender as well as all the message recipients,
press g.By default, mutt uses the
&man.vi.1; editor for creating and replying to emails. Each
user can customize this by creating or editing the
.muttrc in their home directory and
setting the editor variable or by setting
the EDITOR environment variable. Refer to
http://www.mutt.org/
for more information about configuring
mutt.To compose a new mail message, press
m. After a valid subject has been given,
mutt will start &man.vi.1; so the
email can be written. Once the contents of the email are
complete, save and quit from vi.
mutt will resume, displaying a
summary screen of the mail that is to be delivered. In
order to send the mail, press y. An example
of the summary screen can be seen below:mutt contains extensive help
which can be accessed from most of the menus by pressing
?. The top line also displays the keyboard
shortcuts where appropriate.alpinealpine is aimed at a beginner
user, but also includes some advanced features.alpine has had several remote
vulnerabilities discovered in the past, which allowed remote
attackers to execute arbitrary code as users on the local
system, by the action of sending a specially-prepared email.
While known problems have been fixed,
alpine code is written in an
insecure style and the &os; Security Officer believes there
are likely to be other undiscovered vulnerabilities. Users
install alpine at their own
risk.The current version of alpine
may be installed using the mail/alpine
port. Once the port has installed,
alpine can be started by issuing
the following command:&prompt.user; alpineThe first time alpine
runs, it displays a greeting page with a brief introduction,
as well as a request from the
alpine development team to send
an anonymous email message allowing them to judge how many
users are using their client. To send this anonymous message,
press Enter. Alternatively, press
E to exit the greeting without sending an
anonymous message. An example of the greeting page is
shown below:The main menu is then presented, which can be navigated
using the cursor keys. This main menu provides shortcuts for
the composing new mails, browsing mail directories, and
administering address book entries. Below the main menu,
relevant keyboard shortcuts to perform functions specific to
the task at hand are shown.The default directory opened by
alpine is
inbox. To view the message index, press
I, or select the
MESSAGE INDEX option shown
below:The message index shows messages in the current directory
and can be navigated by using the cursor keys. Highlighted
messages can be read by pressing
Enter.In the screenshot below, a sample message is displayed by
alpine. Contextual keyboard
shortcuts are displayed at the bottom of the screen. An
example of one of a shortcut is r, which
tells the MUA to reply to the current
message being displayed.Replying to an email in alpine
is done using the pico editor,
which is installed by default with
alpine.
pico makes it easy to navigate the
message and is easier for novice users to use than &man.vi.1;
or &man.mail.1;. Once the reply is complete, the message can
be sent by pressing CtrlX. alpine will ask for
confirmation before sending the message.alpine can be customized using
the SETUP option from the main
menu. Consult http://www.washington.edu/alpine/
for more information.Using fetchmailMarcSilverContributed by fetchmailfetchmail is a full-featured
IMAP and POP client. It
allows users to automatically download mail from remote
IMAP and POP servers and
save it into local mailboxes where it can be accessed more
easily. fetchmail can be installed
using the mail/fetchmail port, and offers
various features, including:Support for the POP3,
APOP, KPOP,
IMAP, ETRN and
ODMR protocols.Ability to forward mail using SMTP,
which allows filtering, forwarding, and aliasing to function
normally.May be run in daemon mode to check periodically for new
messages.Can retrieve multiple mailboxes and forward them, based
on configuration, to different local users.This section explains some of the basic features of
fetchmail. This utility requires a
.fetchmailrc configuration in the user's
home directory in order to run correctly. This file includes
server information as well as login credentials. Due to the
sensitive nature of the contents of this file, it is advisable
to make it readable only by the user, with the following
command:&prompt.user; chmod 600 .fetchmailrcThe following .fetchmailrc serves as an
example for downloading a single user mailbox using
POP. It tells
fetchmail to connect to
example.com using
a username of joesoap
and a password of XXX. This example assumes
that the user joesoap
exists on the local system.poll example.com protocol pop3 username "joesoap" password "XXX"The next example connects to multiple POP
and IMAP servers and redirects to different
local usernames where applicable:poll example.com proto pop3:
user "joesoap", with password "XXX", is "jsoap" here;
user "andrea", with password "XXXX";
poll example2.net proto imap:
user "john", with password "XXXXX", is "myth" here;fetchmail can be run in daemon
mode by running it with , followed by the
interval (in seconds) that fetchmail
should poll servers listed in .fetchmailrc.
The following example configures
fetchmail to poll every 600
seconds:&prompt.user; fetchmail -d 600More information on fetchmail can
be found at http://www.fetchmail.info/.Using procmailMarcSilverContributed by procmailprocmail is a powerful
application used to filter incoming mail. It allows users to
define rules which can be matched to incoming
mails to perform specific functions or to reroute mail to
alternative mailboxes or email addresses.
procmail can be installed using the
mail/procmail port. Once installed, it can
be directly integrated into most MTAs.
Consult the MTA documentation for more
information. Alternatively, procmail
can be integrated by adding the following line to a
.forward in the home directory of the
user:"|exec /usr/local/bin/procmail || exit 75"The following section displays some basic
procmail rules, as well as brief
descriptions of what they do. Rules must be inserted into a
.procmailrc, which must reside in the
user's home directory.The majority of these rules can be found in
&man.procmailex.5;.To forward all mail from user@example.com to
an external address of goodmail@example2.com::0
* ^From.*user@example.com
! goodmail@example2.comTo forward all mails shorter than 1000 bytes to an external
address of goodmail@example2.com::0
* < 1000
! goodmail@example2.comTo send all mail sent to
alternate@example.com to a mailbox called
alternate::0
* ^TOalternate@example.com
alternateTo send all mail with a subject of Spam to
/dev/null::0
^Subject:.*Spam
/dev/nullA useful recipe that parses incoming &os;.org mailing lists and
places each list in its own mailbox::0
* ^Sender:.owner-freebsd-\/[^@]+@FreeBSD.ORG
{
LISTNAME=${MATCH}
:0
* LISTNAME??^\/[^@]+
FreeBSD-${MATCH}
}
Index: head/en_US.ISO8859-1/books/handbook/network-servers/chapter.xml
===================================================================
--- head/en_US.ISO8859-1/books/handbook/network-servers/chapter.xml (revision 50807)
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Network ServersSynopsisThis chapter covers some of the more frequently used network
services on &unix; systems. This includes installing,
configuring, testing, and maintaining many different types of
network services. Example configuration files are included
throughout this chapter for reference.By the end of this chapter, readers will know:How to manage the inetd
daemon.How to set up the Network File System
(NFS).How to set up the Network Information Server
(NIS) for centralizing and sharing
user accounts.How to set &os; up to act as an LDAP
server or clientHow to set up automatic network settings using
DHCP.How to set up a Domain Name Server
(DNS).How to set up the Apache
HTTP Server.How to set up a File Transfer Protocol
(FTP) server.How to set up a file and print server for &windows;
clients using Samba.How to synchronize the time and date, and set up a
time server using the Network Time Protocol
(NTP).How to set up iSCSI.This chapter assumes a basic knowledge of:/etc/rc scripts.Network terminology.Installation of additional third-party
software ().The inetd
Super-ServerThe &man.inetd.8; daemon is sometimes referred to as a
Super-Server because it manages connections for many services.
Instead of starting multiple applications, only the
inetd service needs to be started.
When a connection is received for a service that is managed by
inetd, it determines which program
the connection is destined for, spawns a process for that
program, and delegates the program a socket. Using
inetd for services that are not
heavily used can reduce system load, when compared to running
each daemon individually in stand-alone mode.Primarily, inetd is used to
spawn other daemons, but several trivial protocols are handled
internally, such as chargen,
auth,
time,
echo,
discard, and
daytime.This section covers the basics of configuring
inetd.Configuration FileConfiguration of inetd is
done by editing /etc/inetd.conf. Each
line of this configuration file represents an application
which can be started by inetd. By
default, every line starts with a comment
(#), meaning that
inetd is not listening for any
applications. To configure inetd
to listen for an application's connections, remove the
# at the beginning of the line for that
application.After saving your edits, configure
inetd to start at system boot by
editing /etc/rc.conf:inetd_enable="YES"To start inetd now, so that it
listens for the service you configured, type:&prompt.root; service inetd startOnce inetd is started, it needs
to be notified whenever a modification is made to
/etc/inetd.conf:Reloading the inetd
Configuration File&prompt.root; service inetd reloadTypically, the default entry for an application does not
need to be edited beyond removing the #.
In some situations, it may be appropriate to edit the default
entry.As an example, this is the default entry for &man.ftpd.8;
over IPv4:ftp stream tcp nowait root /usr/libexec/ftpd ftpd -lThe seven columns in an entry are as follows:service-name
socket-type
protocol
{wait|nowait}[/max-child[/max-connections-per-ip-per-minute[/max-child-per-ip]]]
user[:group][/login-class]
server-program
server-program-argumentswhere:service-nameThe service name of the daemon to start. It must
correspond to a service listed in
/etc/services. This determines
which port inetd listens on
for incoming connections to that service. When using a
custom service, it must first be added to
/etc/services.socket-typeEither stream,
dgram, raw, or
seqpacket. Use
stream for TCP connections and
dgram for
UDP services.protocolUse one of the following protocol names:Protocol NameExplanationtcp or tcp4TCP IPv4udp or udp4UDP IPv4tcp6TCP IPv6udp6UDP IPv6tcp46Both TCP IPv4 and IPv6udp46Both UDP IPv4 and
IPv6{wait|nowait}[/max-child[/max-connections-per-ip-per-minute[/max-child-per-ip]]]In this field, or
must be specified.
,
and
are optional. indicates whether or
not the service is able to handle its own socket.
socket types must use
while
daemons, which are usually
multi-threaded, should use .
usually hands off multiple sockets
to a single daemon, while spawns
a child daemon for each new socket.The maximum number of child daemons
inetd may spawn is set by
. For example, to limit ten
instances of the daemon, place a /10
after . Specifying
/0 allows an unlimited number of
children.
limits the number of connections from any particular
IP address per minute. Once the
limit is reached, further connections from this IP
address will be dropped until the end of the minute.
For example, a value of /10 would
limit any particular IP address to
ten connection attempts per minute.
limits the number of
child processes that can be started on behalf on any
single IP address at any moment.
These options can limit excessive resource consumption
and help to prevent Denial of Service attacks.An example can be seen in the default settings for
&man.fingerd.8;:finger stream tcp nowait/3/10 nobody /usr/libexec/fingerd fingerd -k -suserThe username the daemon
will run as. Daemons typically run as
root,
daemon, or
nobody.server-programThe full path to the daemon. If the daemon is a
service provided by inetd
internally, use .server-program-argumentsUsed to specify any command arguments to be passed
to the daemon on invocation. If the daemon is an
internal service, use
.Command-Line OptionsLike most server daemons, inetd
has a number of options that can be used to modify its
behavior. By default, inetd is
started with -wW -C 60. These options
enable TCP wrappers for all services, including internal
services, and prevent any IP address from
requesting any service more than 60 times per minute.To change the default options which are passed to
inetd, add an entry for
inetd_flags in
/etc/rc.conf. If
inetd is already running, restart
it with service inetd restart.The available rate limiting options are:-c maximumSpecify the default maximum number of simultaneous
invocations of each service, where the default is
unlimited. May be overridden on a per-service basis by
using in
/etc/inetd.conf.-C rateSpecify the default maximum number of times a
service can be invoked from a single
IP address per minute. May be
overridden on a per-service basis by using
in
/etc/inetd.conf.-R rateSpecify the maximum number of times a service can be
invoked in one minute, where the default is
256. A rate of 0
allows an unlimited number.-s maximumSpecify the maximum number of times a service can be
invoked from a single IP address at
any one time, where the default is unlimited. May be
overridden on a per-service basis by using
in
/etc/inetd.conf.Additional options are available. Refer to &man.inetd.8;
for the full list of options.Security ConsiderationsMany of the daemons which can be managed by
inetd are not security-conscious.
Some daemons, such as fingerd, can
provide information that may be useful to an attacker. Only
enable the services which are needed and monitor the system
for excessive connection attempts.
max-connections-per-ip-per-minute,
max-child and
max-child-per-ip can be used to limit such
attacks.By default, TCP wrappers is enabled. Consult
&man.hosts.access.5; for more information on placing TCP
restrictions on various
inetd invoked daemons.Network File System (NFS)TomRhodesReorganized and enhanced by BillSwingleWritten by NFS&os; supports the Network File System
(NFS), which allows a server to share
directories and files with clients over a network. With
NFS, users and programs can access files on
remote systems as if they were stored locally.NFS has many practical uses. Some of
the more common uses include:Data that would otherwise be duplicated on each client
can be kept in a single location and accessed by clients
on the network.Several clients may need access to the
/usr/ports/distfiles directory.
Sharing that directory allows for quick access to the
source files without having to download them to each
client.On large networks, it is often more convenient to
configure a central NFS server on which
all user home directories are stored. Users can log into
a client anywhere on the network and have access to their
home directories.Administration of NFS exports is
simplified. For example, there is only one file system
where security or backup policies must be set.Removable media storage devices can be used by other
machines on the network. This reduces the number of devices
throughout the network and provides a centralized location
to manage their security. It is often more convenient to
install software on multiple machines from a centralized
installation media.NFS consists of a server and one or more
clients. The client remotely accesses the data that is stored
on the server machine. In order for this to function properly,
a few processes have to be configured and running.These daemons must be running on the server:NFSserverfile serverUNIX clientsrpcbindmountdnfsdDaemonDescriptionnfsdThe NFS daemon which services
requests from NFS clients.mountdThe NFS mount daemon which
carries out requests received from
nfsd.rpcbind This daemon allows NFS
clients to discover which port the
NFS server is using.Running &man.nfsiod.8; on the client can improve
performance, but is not required.Configuring the ServerNFSconfigurationThe file systems which the NFS server
will share are specified in /etc/exports.
Each line in this file specifies a file system to be exported,
which clients have access to that file system, and any access
options. When adding entries to this file, each exported file
system, its properties, and allowed hosts must occur on a
single line. If no clients are listed in the entry, then any
client on the network can mount that file system.NFSexport examplesThe following /etc/exports entries
demonstrate how to export file systems. The examples can be
modified to match the file systems and client names on the
reader's network. There are many options that can be used in
this file, but only a few will be mentioned here. See
&man.exports.5; for the full list of options.This example shows how to export
/cdrom to three hosts named
alpha,
bravo, and
charlie:/cdrom -ro alphabravocharlieThe -ro flag makes the file system
read-only, preventing clients from making any changes to the
exported file system. This example assumes that the host
names are either in DNS or in
/etc/hosts. Refer to &man.hosts.5; if
the network does not have a DNS
server.The next example exports /home to
three clients by IP address. This can be
useful for networks without DNS or
/etc/hosts entries. The
-alldirs flag allows subdirectories to be
mount points. In other words, it will not automatically mount
the subdirectories, but will permit the client to mount the
directories that are required as needed./usr/home -alldirs 10.0.0.2 10.0.0.3 10.0.0.4This next example exports /a so that
two clients from different domains may access that file
system. The allows root on the remote system to
write data on the exported file system as root. If
-maproot=root is not specified, the
client's root user
will be mapped to the server's nobody account and will be
subject to the access limitations defined for nobody./a -maproot=root host.example.com box.example.orgA client can only be specified once per file system. For
example, if /usr is a single file system,
these entries would be invalid as both entries specify the
same host:# Invalid when /usr is one file system
/usr/src client
/usr/ports clientThe correct format for this situation is to use one
entry:/usr/src /usr/ports clientThe following is an example of a valid export list, where
/usr and /exports
are local file systems:# Export src and ports to client01 and client02, but only
# client01 has root privileges on it
/usr/src /usr/ports -maproot=root client01
/usr/src /usr/ports client02
# The client machines have root and can mount anywhere
# on /exports. Anyone in the world can mount /exports/obj read-only
/exports -alldirs -maproot=root client01 client02
/exports/obj -roTo enable the processes required by the
NFS server at boot time, add these options
to /etc/rc.conf:rpcbind_enable="YES"
nfs_server_enable="YES"
mountd_flags="-r"The server can be started now by running this
command:&prompt.root; service nfsd startWhenever the NFS server is started,
mountd also starts automatically.
However, mountd only reads
/etc/exports when it is started. To make
subsequent /etc/exports edits take effect
immediately, force mountd to reread
it:&prompt.root; service mountd reloadConfiguring the ClientTo enable NFS clients, set this option
in each client's /etc/rc.conf:nfs_client_enable="YES"Then, run this command on each NFS
client:&prompt.root; service nfsclient startThe client now has everything it needs to mount a remote
file system. In these examples, the server's name is
server and the client's name is
client. To mount
/home on
server to the
/mnt mount point on
client:NFSmounting&prompt.root; mount server:/home /mntThe files and directories in
/home will now be available on
client, in the
/mnt directory.To mount a remote file system each time the client boots,
add it to /etc/fstab:server:/home /mnt nfs rw 0 0Refer to &man.fstab.5; for a description of all available
options.LockingSome applications require file locking to operate
correctly. To enable locking, add these lines to
/etc/rc.conf on both the client and
server:rpc_lockd_enable="YES"
rpc_statd_enable="YES"Then start the applications:&prompt.root; service lockd start
&prompt.root; service statd startIf locking is not required on the server, the
NFS client can be configured to lock
locally by including when running
mount. Refer to &man.mount.nfs.8;
for further details.Automating Mounts with &man.amd.8;WylieStilwellContributed by ChernLeeRewritten by amdautomatic mounter daemonThe automatic mounter daemon,
amd, automatically mounts a remote
file system whenever a file or directory within that file
system is accessed. File systems that are inactive for a
period of time will be automatically unmounted by
amd.This daemon provides an alternative to modifying
/etc/fstab to list every client. It
operates by attaching itself as an NFS
server to the /host and
/net directories. When a file is
accessed within one of these directories,
amd looks up the corresponding
remote mount and automatically mounts it.
/net is used to mount an exported file
system from an IP address while
/host is used to mount an export from a
remote hostname. For instance, an attempt to access a file
within /host/foobar/usr would tell
amd to mount the
/usr export on the host
foobar.Mounting an Export with
amdIn this example, showmount -e shows
the exported file systems that can be mounted from the
NFS server,
foobar:&prompt.user; showmount -e foobar
Exports list on foobar:
/usr 10.10.10.0
/a 10.10.10.0
&prompt.user; cd /host/foobar/usrThe output from showmount shows
/usr as an export. When changing
directories to /host/foobar/usr,
amd intercepts the request and
attempts to resolve the hostname
foobar. If successful,
amd automatically mounts the
desired export.To enable amd at boot time, add
this line to /etc/rc.conf:amd_enable="YES"To start amd now:&prompt.root; service amd startCustom flags can be passed to
amd from the
amd_flags environment variable. By
default, amd_flags is set to:amd_flags="-a /.amd_mnt -l syslog /host /etc/amd.map /net /etc/amd.map"The default options with which exports are mounted are
defined in /etc/amd.map. Some of the
more advanced features of amd are
defined in /etc/amd.conf.Consult &man.amd.8; and &man.amd.conf.5; for more
information.Automating Mounts with &man.autofs.5;The &man.autofs.5; automount facility is supported
starting with &os; 10.1-RELEASE. To use the
automounter functionality in older versions of &os;, use
&man.amd.8; instead. This chapter only describes the
&man.autofs.5; automounter.autofsautomounter subsystemThe &man.autofs.5; facility is a common name for several
components that, together, allow for automatic mounting of
remote and local filesystems whenever a file or directory
within that file system is accessed. It consists of the
kernel component, &man.autofs.5;, and several userspace
applications: &man.automount.8;, &man.automountd.8; and
&man.autounmountd.8;. It serves as an alternative for
&man.amd.8; from previous &os; releases. Amd is still
provided for backward compatibility purposes, as the two use
different map format; the one used by autofs is the same as
with other SVR4 automounters, such as the ones in Solaris,
MacOS X, and Linux.The &man.autofs.5; virtual filesystem is mounted on
specified mountpoints by &man.automount.8;, usually invoked
during boot.Whenever a process attempts to access file within the
&man.autofs.5; mountpoint, the kernel will notify
&man.automountd.8; daemon and pause the triggering process.
The &man.automountd.8; daemon will handle kernel requests by
finding the proper map and mounting the filesystem according
to it, then signal the kernel to release blocked process. The
&man.autounmountd.8; daemon automatically unmounts automounted
filesystems after some time, unless they are still being
used.The primary autofs configuration file is
/etc/auto_master. It assigns individual
maps to top-level mounts. For an explanation of
auto_master and the map syntax, refer to
&man.auto.master.5;.There is a special automounter map mounted on
/net. When a file is accessed within
this directory, &man.autofs.5; looks up the corresponding
remote mount and automatically mounts it. For instance, an
attempt to access a file within
/net/foobar/usr would tell
&man.automountd.8; to mount the /usr export from the host
foobar.Mounting an Export with &man.autofs.5;In this example, showmount -e shows
the exported file systems that can be mounted from the
NFS server,
foobar:&prompt.user; showmount -e foobar
Exports list on foobar:
/usr 10.10.10.0
/a 10.10.10.0
&prompt.user; cd /net/foobar/usrThe output from showmount shows
/usr as an export.
When changing directories to /host/foobar/usr,
&man.automountd.8; intercepts the request and attempts to
resolve the hostname foobar. If successful,
&man.automountd.8; automatically mounts the source
export.To enable &man.autofs.5; at boot time, add this line to
/etc/rc.conf:autofs_enable="YES"Then &man.autofs.5; can be started by running:&prompt.root; service automount start
&prompt.root; service automountd start
&prompt.root; service autounmountd startThe &man.autofs.5; map format is the same as in other
operating systems. Information about this format from other
sources can be useful, like the Mac
OS X document.Consult the &man.automount.8;, &man.automountd.8;,
&man.autounmountd.8;, and &man.auto.master.5; manual pages for
more information.Network Information System
(NIS)NISSolarisHP-UXAIXLinuxNetBSDOpenBSDyellow pagesNISNetwork Information System (NIS) is
designed to centralize administration of &unix;-like systems
such as &solaris;, HP-UX, &aix;, Linux, NetBSD, OpenBSD, and
&os;. NIS was originally known as Yellow
Pages but the name was changed due to trademark issues. This
is the reason why NIS commands begin with
yp.NISdomainsNIS is a Remote Procedure Call
(RPC)-based client/server system that allows
a group of machines within an NIS domain to
share a common set of configuration files. This permits a
system administrator to set up NIS client
systems with only minimal configuration data and to add, remove,
or modify configuration data from a single location.&os; uses version 2 of the NIS
protocol.NIS Terms and ProcessesTable 28.1 summarizes the terms and important processes
used by NIS:rpcbindportmap
NIS TerminologyTermDescriptionNIS domain nameNIS servers and clients share
an NIS domain name. Typically,
this name does not have anything to do with
DNS.&man.rpcbind.8;This service enables RPC and
must be running in order to run an
NIS server or act as an
NIS client.&man.ypbind.8;This service binds an NIS
client to its NIS server. It will
take the NIS domain name and use
RPC to connect to the server. It
is the core of client/server communication in an
NIS environment. If this service
is not running on a client machine, it will not be
able to access the NIS
server.&man.ypserv.8;This is the process for the
NIS server. If this service stops
running, the server will no longer be able to respond
to NIS requests so hopefully, there
is a slave server to take over. Some non-&os; clients
will not try to reconnect using a slave server and the
ypbind process may need to
be restarted on these
clients.&man.rpc.yppasswdd.8;This process only runs on
NIS master servers. This daemon
allows NIS clients to change their
NIS passwords. If this daemon is
not running, users will have to login to the
NIS master server and change their
passwords there.
Machine TypesNISmaster serverNISslave serverNISclientThere are three types of hosts in an
NIS environment:NIS master serverThis server acts as a central repository for host
configuration information and maintains the
authoritative copy of the files used by all of the
NIS clients. The
passwd, group,
and other various files used by NIS
clients are stored on the master server. While it is
possible for one machine to be an NIS
master server for more than one NIS
domain, this type of configuration will not be covered in
this chapter as it assumes a relatively small-scale
NIS environment.NIS slave serversNIS slave servers maintain copies
of the NIS master's data files in
order to provide redundancy. Slave servers also help to
balance the load of the master server as
NIS clients always attach to the
NIS server which responds
first.NIS clientsNIS clients authenticate
against the NIS server during log
on.Information in many files can be shared using
NIS. The
master.passwd,
group, and hosts
files are commonly shared via NIS.
Whenever a process on a client needs information that would
normally be found in these files locally, it makes a query to
the NIS server that it is bound to
instead.Planning ConsiderationsThis section describes a sample NIS
environment which consists of 15 &os; machines with no
centralized point of administration. Each machine has its own
/etc/passwd and
/etc/master.passwd. These files are kept
in sync with each other only through manual intervention.
Currently, when a user is added to the lab, the process must
be repeated on all 15 machines.The configuration of the lab will be as follows:Machine nameIP addressMachine roleellington10.0.0.2NIS mastercoltrane10.0.0.3NIS slavebasie10.0.0.4Faculty workstationbird10.0.0.5Client machinecli[1-11]10.0.0.[6-17]Other client machinesIf this is the first time an NIS
scheme is being developed, it should be thoroughly planned
ahead of time. Regardless of network size, several decisions
need to be made as part of the planning process.Choosing a NIS Domain NameNISdomain nameWhen a client broadcasts its requests for info, it
includes the name of the NIS domain that
it is part of. This is how multiple servers on one network
can tell which server should answer which request. Think of
the NIS domain name as the name for a
group of hosts.Some organizations choose to use their Internet domain
name for their NIS domain name. This is
not recommended as it can cause confusion when trying to
debug network problems. The NIS domain
name should be unique within the network and it is helpful
if it describes the group of machines it represents. For
example, the Art department at Acme Inc. might be in the
acme-art NIS domain. This
example will use the domain name
test-domain.However, some non-&os; operating systems require the
NIS domain name to be the same as the
Internet domain name. If one or more machines on the
network have this restriction, the Internet domain name
must be used as the
NIS domain name.Physical Server RequirementsThere are several things to keep in mind when choosing a
machine to use as a NIS server. Since
NIS clients depend upon the availability
of the server, choose a machine that is not rebooted
frequently. The NIS server should
ideally be a stand alone machine whose sole purpose is to be
an NIS server. If the network is not
heavily used, it is acceptable to put the
NIS server on a machine running other
services. However, if the NIS server
becomes unavailable, it will adversely affect all
NIS clients.Configuring the NIS Master
ServerThe canonical copies of all NIS files
are stored on the master server. The databases used to store
the information are called NIS maps. In
&os;, these maps are stored in
/var/yp/[domainname] where
[domainname] is the name of the
NIS domain. Since multiple domains are
supported, it is possible to have several directories, one for
each domain. Each domain will have its own independent set of
maps.NIS master and slave servers handle all
NIS requests through &man.ypserv.8;. This
daemon is responsible for receiving incoming requests from
NIS clients, translating the requested
domain and map name to a path to the corresponding database
file, and transmitting data from the database back to the
client.NISserver configurationSetting up a master NIS server can be
relatively straight forward, depending on environmental needs.
Since &os; provides built-in NIS support,
it only needs to be enabled by adding the following lines to
/etc/rc.conf:nisdomainname="test-domain"
nis_server_enable="YES"
nis_yppasswdd_enable="YES" This line sets the NIS domain name
to test-domain.This automates the start up of the
NIS server processes when the system
boots.This enables the &man.rpc.yppasswdd.8; daemon so that
users can change their NIS password
from a client machine.Care must be taken in a multi-server domain where the
server machines are also NIS clients. It
is generally a good idea to force the servers to bind to
themselves rather than allowing them to broadcast bind
requests and possibly become bound to each other. Strange
failure modes can result if one server goes down and others
are dependent upon it. Eventually, all the clients will time
out and attempt to bind to other servers, but the delay
involved can be considerable and the failure mode is still
present since the servers might bind to each other all over
again.A server that is also a client can be forced to bind to a
particular server by adding these additional lines to
/etc/rc.conf:nis_client_enable="YES" # run client stuff as well
nis_client_flags="-S NIS domain,server"After saving the edits, type
/etc/netstart to restart the network and
apply the values defined in /etc/rc.conf.
Before initializing the NIS maps, start
&man.ypserv.8;:&prompt.root; service ypserv startInitializing the NIS MapsNISmapsNIS maps are generated from the
configuration files in /etc on the
NIS master, with one exception:
/etc/master.passwd. This is to prevent
the propagation of passwords to all the servers in the
NIS domain. Therefore, before the
NIS maps are initialized, configure the
primary password files:&prompt.root; cp /etc/master.passwd /var/yp/master.passwd
&prompt.root; cd /var/yp
&prompt.root; vi master.passwdIt is advisable to remove all entries for system
accounts as well as any user accounts that do not need to be
propagated to the NIS clients, such as
the root and any
other administrative accounts.Ensure that the
/var/yp/master.passwd is neither
group or world readable by setting its permissions to
600.After completing this task, initialize the
NIS maps. &os; includes the
&man.ypinit.8; script to do this. When generating maps
for the master server, include and
specify the NIS domain name:ellington&prompt.root; ypinit -m test-domain
Server Type: MASTER Domain: test-domain
Creating an YP server will require that you answer a few questions.
Questions will all be asked at the beginning of the procedure.
Do you want this procedure to quit on non-fatal errors? [y/n: n] n
Ok, please remember to go back and redo manually whatever fails.
If not, something might not work.
At this point, we have to construct a list of this domains YP servers.
rod.darktech.org is already known as master server.
Please continue to add any slave servers, one per line. When you are
done with the list, type a <control D>.
master server : ellington
next host to add: coltrane
next host to add: ^D
The current list of NIS servers looks like this:
ellington
coltrane
Is this correct? [y/n: y] y
[..output from map generation..]
NIS Map update completed.
ellington has been setup as an YP master server without any errors.This will create /var/yp/Makefile
from /var/yp/Makefile.dist. By
default, this file assumes that the environment has a
single NIS server with only &os; clients.
Since test-domain has a slave server,
edit this line in /var/yp/Makefile so
that it begins with a comment
(#):NOPUSH = "True"Adding New UsersEvery time a new user is created, the user account must
be added to the master NIS server and the
NIS maps rebuilt. Until this occurs, the
new user will not be able to login anywhere except on the
NIS master. For example, to add the new
user jsmith to the
test-domain domain, run these commands on
the master server:&prompt.root; pw useradd jsmith
&prompt.root; cd /var/yp
&prompt.root; make test-domainThe user could also be added using adduser
jsmith instead of pw useradd
smith.Setting up a NIS Slave ServerNISslave serverTo set up an NIS slave server, log on
to the slave server and edit /etc/rc.conf
as for the master server. Do not generate any
NIS maps, as these already exist on the
master server. When running ypinit on the
slave server, use (for slave) instead of
(for master). This option requires the
name of the NIS master in addition to the
domain name, as seen in this example:coltrane&prompt.root; ypinit -s ellington test-domain
Server Type: SLAVE Domain: test-domain Master: ellington
Creating an YP server will require that you answer a few questions.
Questions will all be asked at the beginning of the procedure.
Do you want this procedure to quit on non-fatal errors? [y/n: n] n
Ok, please remember to go back and redo manually whatever fails.
If not, something might not work.
There will be no further questions. The remainder of the procedure
should take a few minutes, to copy the databases from ellington.
Transferring netgroup...
ypxfr: Exiting: Map successfully transferred
Transferring netgroup.byuser...
ypxfr: Exiting: Map successfully transferred
Transferring netgroup.byhost...
ypxfr: Exiting: Map successfully transferred
Transferring master.passwd.byuid...
ypxfr: Exiting: Map successfully transferred
Transferring passwd.byuid...
ypxfr: Exiting: Map successfully transferred
Transferring passwd.byname...
ypxfr: Exiting: Map successfully transferred
Transferring group.bygid...
ypxfr: Exiting: Map successfully transferred
Transferring group.byname...
ypxfr: Exiting: Map successfully transferred
Transferring services.byname...
ypxfr: Exiting: Map successfully transferred
Transferring rpc.bynumber...
ypxfr: Exiting: Map successfully transferred
Transferring rpc.byname...
ypxfr: Exiting: Map successfully transferred
Transferring protocols.byname...
ypxfr: Exiting: Map successfully transferred
Transferring master.passwd.byname...
ypxfr: Exiting: Map successfully transferred
Transferring networks.byname...
ypxfr: Exiting: Map successfully transferred
Transferring networks.byaddr...
ypxfr: Exiting: Map successfully transferred
Transferring netid.byname...
ypxfr: Exiting: Map successfully transferred
Transferring hosts.byaddr...
ypxfr: Exiting: Map successfully transferred
Transferring protocols.bynumber...
ypxfr: Exiting: Map successfully transferred
Transferring ypservers...
ypxfr: Exiting: Map successfully transferred
Transferring hosts.byname...
ypxfr: Exiting: Map successfully transferred
coltrane has been setup as an YP slave server without any errors.
Remember to update map ypservers on ellington.This will generate a directory on the slave server called
/var/yp/test-domain which contains copies
of the NIS master server's maps. Adding
these /etc/crontab entries on each slave
server will force the slaves to sync their maps with the maps
on the master server:20 * * * * root /usr/libexec/ypxfr passwd.byname
21 * * * * root /usr/libexec/ypxfr passwd.byuidThese entries are not mandatory because the master server
automatically attempts to push any map changes to its slaves.
However, since clients may depend upon the slave server to
provide correct password information, it is recommended to
force frequent password map updates. This is especially
important on busy networks where map updates might not always
complete.To finish the configuration, run
/etc/netstart on the slave server in order
to start the NIS services.Setting Up an NIS ClientAn NIS client binds to an
NIS server using &man.ypbind.8;. This
daemon broadcasts RPC requests on the local network. These
requests specify the domain name configured on the client. If
an NIS server in the same domain receives
one of the broadcasts, it will respond to
ypbind, which will record the
server's address. If there are several servers available,
the client will use the address of the first server to respond
and will direct all of its NIS requests to
that server. The client will automatically
ping the server on a regular basis
to make sure it is still available. If it fails to receive a
reply within a reasonable amount of time,
ypbind will mark the domain as
unbound and begin broadcasting again in the hopes of locating
another server.NISclient configurationTo configure a &os; machine to be an
NIS client:Edit /etc/rc.conf and add the
following lines in order to set the
NIS domain name and start
&man.ypbind.8; during network startup:nisdomainname="test-domain"
nis_client_enable="YES"To import all possible password entries from the
NIS server, use
vipw to remove all user accounts
except one from /etc/master.passwd.
When removing the accounts, keep in mind that at least one
local account should remain and this account should be a
member of wheel. If there is a
problem with NIS, this local account
can be used to log in remotely, become the superuser, and
fix the problem. Before saving the edits, add the
following line to the end of the file:+:::::::::This line configures the client to provide anyone with
a valid account in the NIS server's
password maps an account on the client. There are many
ways to configure the NIS client by
modifying this line. One method is described in . For more detailed
reading, refer to the book
Managing NFS and NIS, published by
O'Reilly Media.To import all possible group entries from the
NIS server, add this line to
/etc/group:+:*::To start the NIS client immediately,
execute the following commands as the superuser:&prompt.root; /etc/netstart
&prompt.root; service ypbind startAfter completing these steps, running
ypcat passwd on the client should show
the server's passwd map.NIS SecuritySince RPC is a broadcast-based service,
any system running ypbind within
the same domain can retrieve the contents of the
NIS maps. To prevent unauthorized
transactions, &man.ypserv.8; supports a feature called
securenets which can be used to restrict access
to a given set of hosts. By default, this information is
stored in /var/yp/securenets, unless
&man.ypserv.8; is started with and an
alternate path. This file contains entries that consist of a
network specification and a network mask separated by white
space. Lines starting with # are
considered to be comments. A sample
securenets might look like this:# allow connections from local host -- mandatory
127.0.0.1 255.255.255.255
# allow connections from any host
# on the 192.168.128.0 network
192.168.128.0 255.255.255.0
# allow connections from any host
# between 10.0.0.0 to 10.0.15.255
# this includes the machines in the testlab
10.0.0.0 255.255.240.0If &man.ypserv.8; receives a request from an address that
matches one of these rules, it will process the request
normally. If the address fails to match a rule, the request
will be ignored and a warning message will be logged. If the
securenets does not exist,
ypserv will allow connections from any
host. is an alternate mechanism
for providing access control instead of
securenets. While either access control
mechanism adds some security, they are both vulnerable to
IP spoofing attacks. All
NIS-related traffic should be blocked at
the firewall.Servers using securenets
may fail to serve legitimate NIS clients
with archaic TCP/IP implementations. Some of these
implementations set all host bits to zero when doing
broadcasts or fail to observe the subnet mask when
calculating the broadcast address. While some of these
problems can be fixed by changing the client configuration,
other problems may force the retirement of these client
systems or the abandonment of
securenets.TCP WrapperThe use of TCP Wrapper
increases the latency of the NIS server.
The additional delay may be long enough to cause timeouts in
client programs, especially in busy networks with slow
NIS servers. If one or more clients suffer
from latency, convert those clients into
NIS slave servers and force them to bind to
themselves.Barring Some UsersIn this example, the basie
system is a faculty workstation within the
NIS domain. The
passwd map on the master
NIS server contains accounts for both
faculty and students. This section demonstrates how to
allow faculty logins on this system while refusing student
logins.To prevent specified users from logging on to a system,
even if they are present in the NIS
database, use vipw to add
-username with
the correct number of colons towards the end of
/etc/master.passwd on the client,
where username is the username of
a user to bar from logging in. The line with the blocked
user must be before the + line that
allows NIS users. In this example,
bill is barred
from logging on to basie:basie&prompt.root; cat /etc/master.passwd
root:[password]:0:0::0:0:The super-user:/root:/bin/csh
toor:[password]:0:0::0:0:The other super-user:/root:/bin/sh
daemon:*:1:1::0:0:Owner of many system processes:/root:/sbin/nologin
operator:*:2:5::0:0:System &:/:/sbin/nologin
bin:*:3:7::0:0:Binaries Commands and Source,,,:/:/sbin/nologin
tty:*:4:65533::0:0:Tty Sandbox:/:/sbin/nologin
kmem:*:5:65533::0:0:KMem Sandbox:/:/sbin/nologin
games:*:7:13::0:0:Games pseudo-user:/usr/games:/sbin/nologin
news:*:8:8::0:0:News Subsystem:/:/sbin/nologin
man:*:9:9::0:0:Mister Man Pages:/usr/share/man:/sbin/nologin
bind:*:53:53::0:0:Bind Sandbox:/:/sbin/nologin
uucp:*:66:66::0:0:UUCP pseudo-user:/var/spool/uucppublic:/usr/libexec/uucp/uucico
xten:*:67:67::0:0:X-10 daemon:/usr/local/xten:/sbin/nologin
pop:*:68:6::0:0:Post Office Owner:/nonexistent:/sbin/nologin
nobody:*:65534:65534::0:0:Unprivileged user:/nonexistent:/sbin/nologin
-bill:::::::::
+:::::::::
basie&prompt.root;Using NetgroupsnetgroupsBarring specified users from logging on to individual
systems becomes unscaleable on larger networks and quickly
loses the main benefit of NIS:
centralized administration.Netgroups were developed to handle large, complex networks
with hundreds of users and machines. Their use is comparable
to &unix; groups, where the main difference is the lack of a
numeric ID and the ability to define a netgroup by including
both user accounts and other netgroups.To expand on the example used in this chapter, the
NIS domain will be extended to add the
users and systems shown in Tables 28.2 and 28.3:
Additional UsersUser Name(s)Descriptionalpha,
betaIT department employeescharlie, deltaIT department apprenticesecho,
foxtrott,
golf,
...employeesable,
baker,
...interns
Additional SystemsMachine Name(s)Descriptionwar,
death,
famine,
pollutionOnly IT employees are allowed to log onto these
servers.pride,
greed,
envy,
wrath,
lust,
slothAll members of the IT department are allowed to
login onto these servers.one,
two,
three,
four,
...Ordinary workstations used by
employees.trashcanA very old machine without any critical data.
Even interns are allowed to use this system.
When using netgroups to configure this scenario, each user
is assigned to one or more netgroups and logins are then
allowed or forbidden for all members of the netgroup. When
adding a new machine, login restrictions must be defined for
all netgroups. When a new user is added, the account must be
added to one or more netgroups. If the
NIS setup is planned carefully, only one
central configuration file needs modification to grant or deny
access to machines.The first step is the initialization of the
NIS netgroup map. In
&os;, this map is not created by default. On the
NIS master server, use an editor to create
a map named /var/yp/netgroup.This example creates four netgroups to represent IT
employees, IT apprentices, employees, and interns:IT_EMP (,alpha,test-domain) (,beta,test-domain)
IT_APP (,charlie,test-domain) (,delta,test-domain)
USERS (,echo,test-domain) (,foxtrott,test-domain) \
(,golf,test-domain)
INTERNS (,able,test-domain) (,baker,test-domain)Each entry configures a netgroup. The first column in an
entry is the name of the netgroup. Each set of brackets
represents either a group of one or more users or the name of
another netgroup. When specifying a user, the three
comma-delimited fields inside each group represent:The name of the host(s) where the other fields
representing the user are valid. If a hostname is not
specified, the entry is valid on all hosts.The name of the account that belongs to this
netgroup.The NIS domain for the account.
Accounts may be imported from other NIS
domains into a netgroup.If a group contains multiple users, separate each user
with whitespace. Additionally, each field may contain
wildcards. See &man.netgroup.5; for details.netgroupsNetgroup names longer than 8 characters should not be
used. The names are case sensitive and using capital letters
for netgroup names is an easy way to distinguish between user,
machine and netgroup names.Some non-&os; NIS clients cannot
handle netgroups containing more than 15 entries. This
limit may be circumvented by creating several sub-netgroups
with 15 users or fewer and a real netgroup consisting of the
sub-netgroups, as seen in this example:BIGGRP1 (,joe1,domain) (,joe2,domain) (,joe3,domain) [...]
BIGGRP2 (,joe16,domain) (,joe17,domain) [...]
BIGGRP3 (,joe31,domain) (,joe32,domain)
BIGGROUP BIGGRP1 BIGGRP2 BIGGRP3Repeat this process if more than 225 (15 times 15) users
exist within a single netgroup.To activate and distribute the new
NIS map:ellington&prompt.root; cd /var/yp
ellington&prompt.root; makeThis will generate the three NIS maps
netgroup,
netgroup.byhost and
netgroup.byuser. Use the map key option
of &man.ypcat.1; to check if the new NIS
maps are available:ellington&prompt.user; ypcat -k netgroup
ellington&prompt.user; ypcat -k netgroup.byhost
ellington&prompt.user; ypcat -k netgroup.byuserThe output of the first command should resemble the
contents of /var/yp/netgroup. The second
command only produces output if host-specific netgroups were
created. The third command is used to get the list of
netgroups for a user.To configure a client, use &man.vipw.8; to specify the
name of the netgroup. For example, on the server named
war, replace this line:+:::::::::with+@IT_EMP:::::::::This specifies that only the users defined in the netgroup
IT_EMP will be imported into this system's
password database and only those users are allowed to login to
this system.This configuration also applies to the
~ function of the shell and all routines
which convert between user names and numerical user IDs. In
other words,
cd ~user will
not work, ls -l will show the numerical ID
instead of the username, and find . -user joe
-print will fail with the message
No such user. To fix this, import all
user entries without allowing them to login into the servers.
This can be achieved by adding an extra line:+:::::::::/sbin/nologinThis line configures the client to import all entries but
to replace the shell in those entries with
/sbin/nologin.Make sure that extra line is placed
after+@IT_EMP:::::::::. Otherwise, all user
accounts imported from NIS will have
/sbin/nologin as their login
shell and no one will be able to login to the system.To configure the less important servers, replace the old
+::::::::: on the servers with these
lines:+@IT_EMP:::::::::
+@IT_APP:::::::::
+:::::::::/sbin/nologinThe corresponding lines for the workstations
would be:+@IT_EMP:::::::::
+@USERS:::::::::
+:::::::::/sbin/nologinNIS supports the creation of netgroups from other
netgroups which can be useful if the policy regarding user
access changes. One possibility is the creation of role-based
netgroups. For example, one might create a netgroup called
BIGSRV to define the login restrictions for
the important servers, another netgroup called
SMALLSRV for the less important servers,
and a third netgroup called USERBOX for the
workstations. Each of these netgroups contains the netgroups
that are allowed to login onto these machines. The new
entries for the NIS
netgroup map would look like this:BIGSRV IT_EMP IT_APP
SMALLSRV IT_EMP IT_APP ITINTERN
USERBOX IT_EMP ITINTERN USERSThis method of defining login restrictions works
reasonably well when it is possible to define groups of
machines with identical restrictions. Unfortunately, this is
the exception and not the rule. Most of the time, the ability
to define login restrictions on a per-machine basis is
required.Machine-specific netgroup definitions are another
possibility to deal with the policy changes. In this
scenario, the /etc/master.passwd of each
system contains two lines starting with +.
The first line adds a netgroup with the accounts allowed to
login onto this machine and the second line adds all other
accounts with /sbin/nologin as shell. It
is recommended to use the ALL-CAPS version of
the hostname as the name of the netgroup:+@BOXNAME:::::::::
+:::::::::/sbin/nologinOnce this task is completed on all the machines, there is
no longer a need to modify the local versions of
/etc/master.passwd ever again. All
further changes can be handled by modifying the
NIS map. Here is an example of a possible
netgroup map for this scenario:# Define groups of users first
IT_EMP (,alpha,test-domain) (,beta,test-domain)
IT_APP (,charlie,test-domain) (,delta,test-domain)
DEPT1 (,echo,test-domain) (,foxtrott,test-domain)
DEPT2 (,golf,test-domain) (,hotel,test-domain)
DEPT3 (,india,test-domain) (,juliet,test-domain)
ITINTERN (,kilo,test-domain) (,lima,test-domain)
D_INTERNS (,able,test-domain) (,baker,test-domain)
#
# Now, define some groups based on roles
USERS DEPT1 DEPT2 DEPT3
BIGSRV IT_EMP IT_APP
SMALLSRV IT_EMP IT_APP ITINTERN
USERBOX IT_EMP ITINTERN USERS
#
# And a groups for a special tasks
# Allow echo and golf to access our anti-virus-machine
SECURITY IT_EMP (,echo,test-domain) (,golf,test-domain)
#
# machine-based netgroups
# Our main servers
WAR BIGSRV
FAMINE BIGSRV
# User india needs access to this server
POLLUTION BIGSRV (,india,test-domain)
#
# This one is really important and needs more access restrictions
DEATH IT_EMP
#
# The anti-virus-machine mentioned above
ONE SECURITY
#
# Restrict a machine to a single user
TWO (,hotel,test-domain)
# [...more groups to follow]It may not always be advisable
to use machine-based netgroups. When deploying a couple of
dozen or hundreds of systems,
role-based netgroups instead of machine-based netgroups may be
used to keep the size of the NIS map within
reasonable limits.Password FormatsNISpassword formatsNIS requires that all hosts within an
NIS domain use the same format for
encrypting passwords. If users have trouble authenticating on
an NIS client, it may be due to a differing
password format. In a heterogeneous network, the format must
be supported by all operating systems, where
DES is the lowest common standard.To check which format a server or client is using, look
at this section of
/etc/login.conf:default:\
:passwd_format=des:\
:copyright=/etc/COPYRIGHT:\
[Further entries elided]In this example, the system is using the
DES format. Other possible values are
blf for Blowfish and md5
for MD5 encrypted passwords.If the format on a host needs to be edited to match the
one being used in the NIS domain, the
login capability database must be rebuilt after saving the
change:&prompt.root; cap_mkdb /etc/login.confThe format of passwords for existing user accounts will
not be updated until each user changes their password
after the login capability database is
rebuilt.Lightweight Directory Access Protocol
(LDAP)TomRhodesWritten by LDAPThe Lightweight Directory Access Protocol
(LDAP) is an application layer protocol used
to access, modify, and authenticate objects using a distributed
directory information service. Think of it as a phone or record
book which stores several levels of hierarchical, homogeneous
information. It is used in Active Directory and
OpenLDAP networks and allows users to
access to several levels of internal information utilizing a
single account. For example, email authentication, pulling
employee contact information, and internal website
authentication might all make use of a single user account in
the LDAP server's record base.This section provides a quick start guide for configuring an
LDAP server on a &os; system. It assumes
that the administrator already has a design plan which includes
the type of information to store, what that information will be
used for, which users should have access to that information,
and how to secure this information from unauthorized
access.LDAP Terminology and StructureLDAP uses several terms which should be
understood before starting the configuration. All directory
entries consist of a group of
attributes. Each of these attribute
sets contains a unique identifier known as a
Distinguished Name
(DN) which is normally built from several
other attributes such as the common or
Relative Distinguished Name
(RDN). Similar to how directories have
absolute and relative paths, consider a DN
as an absolute path and the RDN as the
relative path.An example LDAP entry looks like the
following. This example searches for the entry for the
specified user account (uid),
organizational unit (ou), and organization
(o):&prompt.user; ldapsearch -xb "uid=trhodes,ou=users,o=example.com"
# extended LDIF
#
# LDAPv3
# base <uid=trhodes,ou=users,o=example.com> with scope subtree
# filter: (objectclass=*)
# requesting: ALL
#
# trhodes, users, example.com
dn: uid=trhodes,ou=users,o=example.com
mail: trhodes@example.com
cn: Tom Rhodes
uid: trhodes
telephoneNumber: (123) 456-7890
# search result
search: 2
result: 0 Success
# numResponses: 2
# numEntries: 1This example entry shows the values for the
dn, mail,
cn, uid, and
telephoneNumber attributes. The
cn attribute is the
RDN.More information about LDAP and its
terminology can be found at http://www.openldap.org/doc/admin24/intro.html.Configuring an LDAP ServerLDAP Server&os; does not provide a built-in LDAP
server. Begin the configuration by installing the net/openldap24-server package or port.
Since the port has many configurable options, it is
recommended that the default options are reviewed to see if
the package is sufficient, and to instead compile the port if
any options should be changed. In most cases, the defaults
are fine. However, if SQL support is needed, this option must
be enabled and the port compiled using the instructions in
.Next, create the directories to hold the data and to store
the certificates:&prompt.root; mkdir /var/db/openldap-data
&prompt.root; mkdir /usr/local/etc/openldap/privateCopy over the database configuration file:&prompt.root; cp /usr/local/etc/openldap/DB_CONFIG.example /var/db/openldap-data/DB_CONFIGThe next phase is to configure the certificate authority.
The following commands must be executed from
/usr/local/etc/openldap/private. This is
important as the file permissions need to be restrictive and
users should not have access to these files. To create the
certificate authority, start with this command and follow the
prompts:&prompt.root; openssl req -days 365 -nodes -new -x509 -keyout ca.key -out ../ca.crtThe entries for the prompts may be generic
except for the
Common Name. This entry must be
different than the system hostname. If
this will be a self signed certificate, prefix the hostname
with CA for certificate authority.The next task is to create a certificate signing request
and a private key. Input this command and follow the
prompts:&prompt.root; openssl req -days 365 -nodes -new -keyout server.key -out server.csrDuring the certificate generation process, be sure to
correctly set the Common Name attribute.
Once complete, sign the key:&prompt.root; openssl x509 -req -days 365 -in server.csr -out ../server.crt -CA ../ca.crt -CAkey ca.key -CAcreateserialThe final part of the certificate generation process is to
generate and sign the client certificates:&prompt.root; openssl req -days 365 -nodes -new -keyout client.key -out client.csr
&prompt.root; openssl x509 -req -days 3650 -in client.csr -out ../client.crt -CA ../ca.crt -CAkey ca.keyRemember to use the same Common Name
attribute when prompted. When finished, ensure that a total
of eight (8) new files have been generated through the
proceeding commands. If so, the next step is to edit
/usr/local/etc/openldap/slapd.conf and
add the following options:TLSCipherSuite HIGH:MEDIUM:+SSLv3
TLSCertificateFile /usr/local/etc/openldap/server.crt
TLSCertificateKeyFile /usr/local/etc/openldap/private/server.key
TLSCACertificateFile /usr/local/etc/openldap/ca.crtThen, edit
/usr/local/etc/openldap/ldap.conf and add
the following lines:TLS_CACERT /usr/local/etc/openldap/ca.crt
TLS_CIPHER_SUITE HIGH:MEDIUM:+SSLv3While editing this file, uncomment the following entries
and set them to the desired values: ,
, and
. Set the to
contain and
. Then, add two entries pointing to
the certificate authority. When finished, the entries should
look similar to the following:BASE dc=example,dc=com
URI ldap:// ldaps://
SIZELIMIT 12
TIMELIMIT 15
TLS_CACERT /usr/local/etc/openldap/ca.crt
TLS_CIPHER_SUITE HIGH:MEDIUM:+SSLv3The default password for the server should then be
changed:&prompt.root; slappasswd -h "{SHA}" >> /usr/local/etc/openldap/slapd.confThis command will prompt for the password and, if the
process does not fail, a password hash will be added to the
end of slapd.conf. Several hashing
formats are supported. Refer to the manual page for
slappasswd for more information.Next, edit
/usr/local/etc/openldap/slapd.conf and
add the following lines:password-hash {sha}
allow bind_v2The in this file must be updated
to match the used in
/usr/local/etc/openldap/ldap.conf and
should also be set. A recommended
value for is something like
. Before saving this file, place
the in front of the password output
from slappasswd and delete the old
. The end result should
look similar to this:TLSCipherSuite HIGH:MEDIUM:+SSLv3
TLSCertificateFile /usr/local/etc/openldap/server.crt
TLSCertificateKeyFile /usr/local/etc/openldap/private/server.key
TLSCACertificateFile /usr/local/etc/openldap/ca.crt
rootpw {SHA}W6ph5Mm5Pz8GgiULbPgzG37mj9g=Finally, enable the OpenLDAP
service in /etc/rc.conf and set the
URI:slapd_enable="YES"
slapd_flags="-4 -h ldaps:///"At this point the server can be started and tested:&prompt.root; service slapd startIf everything is configured correctly, a search of the
directory should show a successful connection with a single
response as in this example:&prompt.root; ldapsearch -Z
# extended LDIF
#
# LDAPv3
# base <dc=example,dc=com> (default) with scope subtree
# filter: (objectclass=*)
# requesting: ALL
#
# search result
search: 3
result: 32 No such object
# numResponses: 1If the command fails and the configuration looks
correct, stop the slapd service and
restart it with debugging options:&prompt.root; service slapd stop
&prompt.root; /usr/local/libexec/slapd -d -1Once the service is responding, the directory can be
populated using ldapadd. In this example,
a file containing this list of users is first created. Each
user should use the following format:dn: dc=example,dc=com
objectclass: dcObject
objectclass: organization
o: Example
dc: Example
dn: cn=Manager,dc=example,dc=com
objectclass: organizationalRole
cn: ManagerTo import this file, specify the file name. The following
command will prompt for the password specified earlier and the
output should look something like this:&prompt.root; ldapadd -Z -D "cn=Manager,dc=example,dc=com" -W -f import.ldif
Enter LDAP Password:
adding new entry "dc=example,dc=com"
adding new entry "cn=Manager,dc=example,dc=com"Verify the data was added by issuing a search on the
server using ldapsearch:&prompt.user; ldapsearch -Z
# extended LDIF
#
# LDAPv3
# base <dc=example,dc=com> (default) with scope subtree
# filter: (objectclass=*)
# requesting: ALL
#
# example.com
dn: dc=example,dc=com
objectClass: dcObject
objectClass: organization
o: Example
dc: Example
# Manager, example.com
dn: cn=Manager,dc=example,dc=com
objectClass: organizationalRole
cn: Manager
# search result
search: 3
result: 0 Success
# numResponses: 3
# numEntries: 2At this point, the server should be configured and
functioning properly.Dynamic Host Configuration Protocol
(DHCP)Dynamic Host Configuration ProtocolDHCPInternet Systems Consortium (ISC)The Dynamic Host Configuration Protocol
(DHCP) allows a system to connect to a
network in order to be assigned the necessary addressing
information for communication on that network. &os; includes
the OpenBSD version of dhclient which is used
by the client to obtain the addressing information. &os; does
not install a DHCP server, but several
servers are available in the &os; Ports Collection. The
DHCP protocol is fully described in RFC
2131.
Informational resources are also available at isc.org/downloads/dhcp/.This section describes how to use the built-in
DHCP client. It then describes how to
install and configure a DHCP server.In &os;, the &man.bpf.4; device is needed by both the
DHCP server and DHCP
client. This device is included in the
GENERIC kernel that is installed with
&os;. Users who prefer to create a custom kernel need to keep
this device if DHCP is used.It should be noted that bpf also
allows privileged users to run network packet sniffers on
that system.Configuring a DHCP ClientDHCP client support is included in the
&os; installer, making it easy to configure a newly installed
system to automatically receive its networking addressing
information from an existing DHCP server.
Refer to for examples of
network configuration.UDPWhen dhclient is executed on the client
machine, it begins broadcasting requests for configuration
information. By default, these requests use
UDP port 68. The server replies on
UDP port 67, giving the client an
IP address and other relevant network
information such as a subnet mask, default gateway, and
DNS server addresses. This information is
in the form of a DHCP
lease and is valid for a configurable time.
This allows stale IP addresses for clients
no longer connected to the network to automatically be reused.
DHCP clients can obtain a great deal of
information from the server. An exhaustive list may be found
in &man.dhcp-options.5;.By default, when a &os; system boots, its
DHCP client runs in the background, or
asynchronously. Other startup scripts
continue to run while the DHCP process
completes, which speeds up system startup.Background DHCP works well when the
DHCP server responds quickly to the
client's requests. However, DHCP may take
a long time to complete on some systems. If network services
attempt to run before DHCP has assigned the
network addressing information, they will fail. Using
DHCP in synchronous
mode prevents this problem as it pauses startup until the
DHCP configuration has completed.This line in /etc/rc.conf is used to
configure background or asynchronous mode:ifconfig_fxp0="DHCP"This line may already exist if the system was configured
to use DHCP during installation. Replace
the fxp0 shown in these examples
with the name of the interface to be dynamically configured,
as described in .To instead configure the system to use synchronous mode,
and to pause during startup while DHCP
completes, use
SYNCDHCP:ifconfig_fxp0="SYNCDHCP"Additional client options are available. Search for
dhclient in &man.rc.conf.5; for
details.DHCPconfiguration filesThe DHCP client uses the following
files:/etc/dhclient.confThe configuration file used by
dhclient. Typically, this file
contains only comments as the defaults are suitable for
most clients. This configuration file is described in
&man.dhclient.conf.5;./sbin/dhclientMore information about the command itself can
be found in &man.dhclient.8;./sbin/dhclient-scriptThe
&os;-specific DHCP client configuration
script. It is described in &man.dhclient-script.8;, but
should not need any user modification to function
properly./var/db/dhclient.leases.interfaceThe DHCP client keeps a database of
valid leases in this file, which is written as a log and
is described in &man.dhclient.leases.5;.Installing and Configuring a DHCP
ServerThis section demonstrates how to configure a &os; system
to act as a DHCP server using the Internet
Systems Consortium (ISC) implementation of
the DHCP server. This implementation and
its documentation can be installed using the
net/isc-dhcp43-server package or
port.DHCPserverDHCPinstallationThe installation of
net/isc-dhcp43-server installs a sample
configuration file. Copy
/usr/local/etc/dhcpd.conf.example to
/usr/local/etc/dhcpd.conf and make any
edits to this new file.DHCPdhcpd.confThe configuration file is comprised of declarations for
subnets and hosts which define the information that is
provided to DHCP clients. For example,
these lines configure the following:option domain-name "example.org";
option domain-name-servers ns1.example.org;
option subnet-mask 255.255.255.0;
default-lease-time 600;
max-lease-time 72400;
ddns-update-style none;
subnet 10.254.239.0 netmask 255.255.255.224 {
range 10.254.239.10 10.254.239.20;
option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;
}
host fantasia {
hardware ethernet 08:00:07:26:c0:a5;
fixed-address fantasia.fugue.com;
}This option specifies the default search domain that
will be provided to clients. Refer to
&man.resolv.conf.5; for more information.This option specifies a comma separated list of
DNS servers that the client should use.
They can be listed by their Fully Qualified Domain Names
(FQDN), as seen in the example, or by
their IP addresses.The subnet mask that will be provided to
clients.The default lease expiry time in seconds. A client
can be configured to override this value. The maximum allowed length of time, in seconds, for a
lease. Should a client request a longer lease, a lease
will still be issued, but it will only be valid for
max-lease-time.The default of disables dynamic
DNS updates. Changing this to
configures the DHCP server to update a
DNS server whenever it hands out a
lease so that the DNS server knows
which IP addresses are associated with
which computers in the network. Do not change the default
setting unless the DNS server has been
configured to support dynamic
DNS.This line creates a pool of available
IP addresses which are reserved for
allocation to DHCP clients. The range
of addresses must be valid for the network or subnet
specified in the previous line.Declares the default gateway that is valid for the
network or subnet specified before the opening
{ bracket.Specifies the hardware MAC address
of a client so that the DHCP server can
recognize the client when it makes a request.Specifies that this host should always be given the
same IP address. Using the hostname is
correct, since the DHCP server will
resolve the hostname before returning the lease
information.This configuration file supports many more options. Refer
to dhcpd.conf(5), installed with the server, for details and
examples.Once the configuration of dhcpd.conf
is complete, enable the DHCP server in
/etc/rc.conf:dhcpd_enable="YES"
dhcpd_ifaces="dc0"Replace the dc0 with the interface (or
interfaces, separated by whitespace) that the
DHCP server should listen on for
DHCP client requests.Start the server by issuing the following command:&prompt.root; service isc-dhcpd startAny future changes to the configuration of the server will
require the dhcpd service to be
stopped and then started using &man.service.8;.The DHCP server uses the following
files. Note that the manual pages are installed with the
server software.DHCPconfiguration files/usr/local/sbin/dhcpdMore information about the
dhcpd server can be found in
dhcpd(8)./usr/local/etc/dhcpd.confThe server configuration file needs to contain all the
information that should be provided to clients, along with
information regarding the operation of the server. This
configuration file is described in dhcpd.conf(5)./var/db/dhcpd.leasesThe DHCP server keeps a database of
leases it has issued in this file, which is written as a
log. Refer to dhcpd.leases(5), which gives a slightly
longer description./usr/local/sbin/dhcrelayThis daemon is used in advanced environments where one
DHCP server forwards a request from a
client to another DHCP server on a
separate network. If this functionality is required,
install the net/isc-dhcp43-relay
package or port. The installation includes dhcrelay(8)
which provides more detail.Domain Name System (DNS)DNSDomain Name System (DNS) is the protocol
through which domain names are mapped to IP
addresses, and vice versa. DNS is
coordinated across the Internet through a somewhat complex
system of authoritative root, Top Level Domain
(TLD), and other smaller-scale name servers,
which host and cache individual domain information. It is not
necessary to run a name server to perform
DNS lookups on a system.BINDIn &os; 10, the Berkeley Internet Name Domain
(BIND) has been removed from the base system
and replaced with Unbound. Unbound as configured in the &os;
Base is a local caching resolver. BIND is
still available from The Ports Collection as dns/bind99 or dns/bind98. In &os; 9 and lower,
BIND is included in &os; Base. The &os;
version provides enhanced security features, a new file system
layout, and automated &man.chroot.8; configuration.
BIND is maintained by the Internet Systems
Consortium.resolverreverse
DNSroot zoneThe following table describes some of the terms associated
with DNS:
DNS TerminologyTermDefinitionForward DNSMapping of hostnames to IP
addresses.OriginRefers to the domain covered in a particular zone
file.named, BINDCommon names for the BIND name server package
within &os;.ResolverA system process through which a machine queries
a name server for zone information.Reverse DNSMapping of IP addresses to
hostnames.Root zoneThe beginning of the Internet zone hierarchy. All
zones fall under the root zone, similar to how all files
in a file system fall under the root directory.ZoneAn individual domain, subdomain, or portion of the
DNS administered by the same
authority.
zonesexamplesExamples of zones:. is how the root zone is
usually referred to in documentation.org. is a Top Level Domain
(TLD) under the root zone.example.org. is a zone
under the org.
TLD.1.168.192.in-addr.arpa is a
zone referencing all IP addresses which
fall under the 192.168.1.*
IP address space.As one can see, the more specific part of a hostname
appears to its left. For example, example.org. is more
specific than org., as
org. is more specific than the root
zone. The layout of each part of a hostname is much like a file
system: the /dev directory falls within the
root, and so on.Reasons to Run a Name ServerName servers generally come in two forms: authoritative
name servers, and caching (also known as resolving) name
servers.An authoritative name server is needed when:One wants to serve DNS information
to the world, replying authoritatively to queries.A domain, such as example.org, is
registered and IP addresses need to be
assigned to hostnames under it.An IP address block requires
reverse DNS entries
(IP to hostname).A backup or second name server, called a slave, will
reply to queries.A caching name server is needed when:A local DNS server may cache and
respond more quickly than querying an outside name
server.When one queries for www.FreeBSD.org, the
resolver usually queries the uplink ISP's
name server, and retrieves the reply. With a local, caching
DNS server, the query only has to be made
once to the outside world by the caching
DNS server. Additional queries will not
have to go outside the local network, since the information is
cached locally.DNS Server Configuration in &os; 10.0
and LaterIn &os; 10.0, BIND has been
replaced with Unbound.
Unbound is a validating caching
resolver only. If an authoritative server is needed, many are
available from the Ports Collection.Unbound is provided in the &os;
base system. By default, it will provide
DNS resolution to the local machine only.
While the base system package can be configured to provide
resolution services beyond the local machine, it is
recommended that such requirements be addressed by installing
Unbound from the &os; Ports
Collection.To enable Unbound, add the
following to /etc/rc.conf:local_unbound_enable="YES"Any existing nameservers in
/etc/resolv.conf will be configured as
forwarders in the new Unbound
configuration.If any of the listed nameservers do not support
DNSSEC, local DNS
resolution will fail. Be sure to test each nameserver and
remove any that fail the test. The following command will
show the trust tree or a failure for a nameserver running on
192.168.1.1:&prompt.user; drill -S FreeBSD.org @192.168.1.1Once each nameserver is confirmed to support
DNSSEC, start
Unbound:&prompt.root; service local_unbound onestartThis will take care of updating
/etc/resolv.conf so that queries for
DNSSEC secured domains will now work. For
example, run the following to validate the FreeBSD.org
DNSSEC trust tree:&prompt.user; drill -S FreeBSD.org
;; Number of trusted keys: 1
;; Chasing: freebsd.org. A
DNSSEC Trust tree:
freebsd.org. (A)
|---freebsd.org. (DNSKEY keytag: 36786 alg: 8 flags: 256)
|---freebsd.org. (DNSKEY keytag: 32659 alg: 8 flags: 257)
|---freebsd.org. (DS keytag: 32659 digest type: 2)
|---org. (DNSKEY keytag: 49587 alg: 7 flags: 256)
|---org. (DNSKEY keytag: 9795 alg: 7 flags: 257)
|---org. (DNSKEY keytag: 21366 alg: 7 flags: 257)
|---org. (DS keytag: 21366 digest type: 1)
| |---. (DNSKEY keytag: 40926 alg: 8 flags: 256)
| |---. (DNSKEY keytag: 19036 alg: 8 flags: 257)
|---org. (DS keytag: 21366 digest type: 2)
|---. (DNSKEY keytag: 40926 alg: 8 flags: 256)
|---. (DNSKEY keytag: 19036 alg: 8 flags: 257)
;; Chase successfulDNS Server Configuration in &os;
9.XIn &os;, the BIND daemon is called
named.FileDescription&man.named.8;The BIND daemon.&man.rndc.8;Name server control utility./etc/namedbDirectory where BIND zone information
resides./etc/namedb/named.confConfiguration file of the daemon.Depending on how a given zone is configured on the server,
the files related to that zone can be found in the
master,
slave, or
dynamic subdirectories
of the /etc/namedb
directory. These files contain the DNS
information that will be given out by the name server in
response to queries.Starting BINDBINDstartingSince BIND is installed by default, configuring it is
relatively simple.The default named
configuration is that of a basic resolving name server,
running in a &man.chroot.8; environment, and restricted to
listening on the local IPv4 loopback address (127.0.0.1).
To start the server one time with this configuration, use
the following command:&prompt.root; service named onestartTo ensure the named daemon is
started at boot each time, put the following line into the
/etc/rc.conf:named_enable="YES"There are many configuration options for
/etc/namedb/named.conf that are beyond
the scope of this document. Other startup options for
named on &os; can be found in the
named_* flags
in /etc/defaults/rc.conf and in
&man.rc.conf.5;. The
section is also a good read.Configuration FilesBINDconfiguration filesConfiguration files for named
currently reside in /etc/namedb
directory and will need modification before use unless all
that is needed is a simple resolver. This is where most of
the configuration will be performed./etc/namedb/named.conf
- // $FreeBSD$
+ // $FreeBSD$
//
// Refer to the named.conf(5) and named(8) man pages, and the documentation
// in /usr/share/doc/bind9 for more details.
//
// If you are going to set up an authoritative server, make sure you
// understand the hairy details of how DNS works. Even with
// simple mistakes, you can break connectivity for affected parties,
// or cause huge amounts of useless Internet traffic.
options {
// All file and path names are relative to the chroot directory,
// if any, and should be fully qualified.
directory "/etc/namedb/working";
pid-file "/var/run/named/pid";
dump-file "/var/dump/named_dump.db";
statistics-file "/var/stats/named.stats";
// If named is being used only as a local resolver, this is a safe default.
// For named to be accessible to the network, comment this option, specify
// the proper IP address, or delete this option.
listen-on { 127.0.0.1; };
// If you have IPv6 enabled on this system, uncomment this option for
// use as a local resolver. To give access to the network, specify
// an IPv6 address, or the keyword "any".
// listen-on-v6 { ::1; };
// These zones are already covered by the empty zones listed below.
// If you remove the related empty zones below, comment these lines out.
disable-empty-zone "255.255.255.255.IN-ADDR.ARPA";
disable-empty-zone "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA";
disable-empty-zone "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA";
// If you have a DNS server around at your upstream provider, enter
// its IP address here, and enable the line below. This will make you
// benefit from its cache, thus reduce overall DNS traffic in the Internet.
/*
forwarders {
127.0.0.1;
};
*/
// If the 'forwarders' clause is not empty the default is to 'forward first'
// which will fall back to sending a query from your local server if the name
// servers in 'forwarders' do not have the answer. Alternatively you can
// force your name server to never initiate queries of its own by enabling the
// following line:
// forward only;
// If you wish to have forwarding configured automatically based on
// the entries in /etc/resolv.conf, uncomment the following line and
// set named_auto_forward=yes in /etc/rc.conf. You can also enable
// named_auto_forward_only (the effect of which is described above).
// include "/etc/namedb/auto_forward.conf";Just as the comment says, to benefit from an uplink's
cache, forwarders can be enabled here.
Under normal circumstances, a name server will recursively
query the Internet looking at certain name servers until
it finds the answer it is looking for. Having this
enabled will have it query the uplink's name server (or
name server provided) first, taking advantage of its
cache. If the uplink name server in question is a heavily
trafficked, fast name server, enabling this may be
worthwhile.127.0.0.1
will not work here. Change this
IP address to a name server at the
uplink. /*
Modern versions of BIND use a random UDP port for each outgoing
query by default in order to dramatically reduce the possibility
of cache poisoning. All users are strongly encouraged to utilize
this feature, and to configure their firewalls to accommodate it.
AS A LAST RESORT in order to get around a restrictive firewall
policy you can try enabling the option below. Use of this option
will significantly reduce your ability to withstand cache poisoning
attacks, and should be avoided if at all possible.
Replace NNNNN in the example with a number between 49160 and 65530.
*/
// query-source address * port NNNNN;
};
// If you enable a local name server, do not forget to enter 127.0.0.1
// first in your /etc/resolv.conf so this server will be queried.
// Also, make sure to enable it in /etc/rc.conf.
// The traditional root hints mechanism. Use this, OR the slave zones below.
zone "." { type hint; file "/etc/namedb/named.root"; };
/* Slaving the following zones from the root name servers has some
significant advantages:
1. Faster local resolution for your users
2. No spurious traffic will be sent from your network to the roots
3. Greater resilience to any potential root server failure/DDoS
On the other hand, this method requires more monitoring than the
hints file to be sure that an unexpected failure mode has not
incapacitated your server. Name servers that are serving a lot
of clients will benefit more from this approach than individual
hosts. Use with caution.
To use this mechanism, uncomment the entries below, and comment
the hint zone above.
As documented at http://dns.icann.org/services/axfr/ these zones:
"." (the root), ARPA, IN-ADDR.ARPA, IP6.ARPA, and ROOT-SERVERS.NET
are available for AXFR from these servers on IPv4 and IPv6:
xfr.lax.dns.icann.org, xfr.cjr.dns.icann.org
*/
/*
zone "." {
type slave;
file "/etc/namedb/slave/root.slave";
masters {
192.5.5.241; // F.ROOT-SERVERS.NET.
};
notify no;
};
zone "arpa" {
type slave;
file "/etc/namedb/slave/arpa.slave";
masters {
192.5.5.241; // F.ROOT-SERVERS.NET.
};
notify no;
};
*/
/* Serving the following zones locally will prevent any queries
for these zones leaving your network and going to the root
name servers. This has two significant advantages:
1. Faster local resolution for your users
2. No spurious traffic will be sent from your network to the roots
*/
// RFCs 1912 and 5735 (and BCP 32 for localhost)
zone "localhost" { type master; file "/etc/namedb/master/localhost-forward.db"; };
zone "127.in-addr.arpa" { type master; file "/etc/namedb/master/localhost-reverse.db"; };
zone "255.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// RFC 1912-style zone for IPv6 localhost address
zone "0.ip6.arpa" { type master; file "/etc/namedb/master/localhost-reverse.db"; };
// "This" Network (RFCs 1912 and 5735)
zone "0.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// Private Use Networks (RFCs 1918 and 5735)
zone "10.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "16.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "17.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "18.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "19.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "20.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "21.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "22.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "23.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "24.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "25.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "26.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "27.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "28.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "29.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "30.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "31.172.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "168.192.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// Link-local/APIPA (RFCs 3927 and 5735)
zone "254.169.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// IETF protocol assignments (RFCs 5735 and 5736)
zone "0.0.192.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// TEST-NET-[1-3] for Documentation (RFCs 5735 and 5737)
zone "2.0.192.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "100.51.198.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "113.0.203.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// IPv6 Range for Documentation (RFC 3849)
zone "8.b.d.0.1.0.0.2.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// Domain Names for Documentation and Testing (BCP 32)
zone "test" { type master; file "/etc/namedb/master/empty.db"; };
zone "example" { type master; file "/etc/namedb/master/empty.db"; };
zone "invalid" { type master; file "/etc/namedb/master/empty.db"; };
zone "example.com" { type master; file "/etc/namedb/master/empty.db"; };
zone "example.net" { type master; file "/etc/namedb/master/empty.db"; };
zone "example.org" { type master; file "/etc/namedb/master/empty.db"; };
// Router Benchmark Testing (RFCs 2544 and 5735)
zone "18.198.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "19.198.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// IANA Reserved - Old Class E Space (RFC 5735)
zone "240.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "241.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "242.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "243.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "244.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "245.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "246.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "247.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "248.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "249.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "250.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "251.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "252.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "253.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "254.in-addr.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// IPv6 Unassigned Addresses (RFC 4291)
zone "1.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "3.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "4.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "5.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "6.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "7.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "8.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "9.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "a.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "b.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "c.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "d.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "e.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "0.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "1.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "2.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "3.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "4.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "5.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "6.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "7.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "8.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "9.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "a.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "b.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "0.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "1.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "2.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "3.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "4.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "5.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "6.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "7.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// IPv6 ULA (RFC 4193)
zone "c.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "d.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// IPv6 Link Local (RFC 4291)
zone "8.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "9.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "a.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "b.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// IPv6 Deprecated Site-Local Addresses (RFC 3879)
zone "c.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "d.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "e.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
zone "f.e.f.ip6.arpa" { type master; file "/etc/namedb/master/empty.db"; };
// IP6.INT is Deprecated (RFC 4159)
zone "ip6.int" { type master; file "/etc/namedb/master/empty.db"; };
// NB: Do not use the IP addresses below, they are faked, and only
// serve demonstration/documentation purposes!
//
// Example slave zone config entries. It can be convenient to become
// a slave at least for the zone your own domain is in. Ask
// your network administrator for the IP address of the responsible
// master name server.
//
// Do not forget to include the reverse lookup zone!
// This is named after the first bytes of the IP address, in reverse
// order, with ".IN-ADDR.ARPA" appended, or ".IP6.ARPA" for IPv6.
//
// Before starting to set up a master zone, make sure you fully
// understand how DNS and BIND work. There are sometimes
// non-obvious pitfalls. Setting up a slave zone is usually simpler.
//
// NB: Do not blindly enable the examples below. :-) Use actual names
// and addresses instead.
/* An example dynamic zone
key "exampleorgkey" {
algorithm hmac-md5;
secret "sf87HJqjkqh8ac87a02lla==";
};
zone "example.org" {
type master;
allow-update {
key "exampleorgkey";
};
file "/etc/namedb/dynamic/example.org";
};
*/
/* Example of a slave reverse zone
zone "1.168.192.in-addr.arpa" {
type slave;
file "/etc/namedb/slave/1.168.192.in-addr.arpa";
masters {
192.168.1.1;
};
};
*/In named.conf, these are examples
of slave entries for a forward and reverse zone.For each new zone served, a new zone entry must be
added to named.conf.For example, the simplest zone entry for
example.org
can look like:zone "example.org" {
type master;
file "master/example.org";
};The zone is a master, as indicated by the
statement, holding its zone
information in
/etc/namedb/master/example.org
indicated by the statement.zone "example.org" {
type slave;
file "slave/example.org";
};In the slave case, the zone information is transferred
from the master name server for the particular zone, and
saved in the file specified. If and when the master
server dies or is unreachable, the slave name server will
have the transferred zone information and will be able to
serve it.Zone FilesBINDzone filesAn example master zone file for
example.org
(existing within
/etc/namedb/master/example.org) is as
follows:$TTL 3600 ; 1 hour default TTL
example.org. IN SOA ns1.example.org. admin.example.org. (
2006051501 ; Serial
10800 ; Refresh
3600 ; Retry
604800 ; Expire
300 ; Negative Response TTL
)
; DNS Servers
IN NS ns1.example.org.
IN NS ns2.example.org.
; MX Records
IN MX 10 mx.example.org.
IN MX 20 mail.example.org.
IN A 192.168.1.1
; Machine Names
localhost IN A 127.0.0.1
ns1 IN A 192.168.1.2
ns2 IN A 192.168.1.3
mx IN A 192.168.1.4
mail IN A 192.168.1.5
; Aliases
www IN CNAME example.org.Note that every hostname ending in a .
is an exact hostname, whereas everything without a
trailing . is relative to the origin. For
example, ns1 is translated into
ns1.example.org.The format of a zone file follows:recordname IN recordtype valueDNSrecordsThe most commonly used DNS
records:SOAstart of zone authorityNSan authoritative name serverAa host addressCNAMEthe canonical name for an aliasMXmail exchangerPTRa domain name pointer (used in reverse
DNS)example.org. IN SOA ns1.example.org. admin.example.org. (
2006051501 ; Serial
10800 ; Refresh after 3 hours
3600 ; Retry after 1 hour
604800 ; Expire after 1 week
300 ) ; Negative Response TTLexample.org.the domain name, also the origin for this
zone file.ns1.example.org.the primary/authoritative name server for this
zone.admin.example.org.the responsible person for this zone,
email address with @
replaced. (admin@example.org becomes
admin.example.org)2006051501the serial number of the file. This must be
incremented each time the zone file is modified.
Nowadays, many admins prefer a
yyyymmddrr format for the serial
number. 2006051501 would mean
last modified 05/15/2006, the latter
01 being the first time the zone
file has been modified this day. The serial number
is important as it alerts slave name servers for a
zone when it is updated. IN NS ns1.example.org.This is an NS entry. Every name server that is going
to reply authoritatively for the zone must have one of
these entries.localhost IN A 127.0.0.1
ns1 IN A 192.168.1.2
ns2 IN A 192.168.1.3
mx IN A 192.168.1.4
mail IN A 192.168.1.5The A record indicates machine names. As seen above,
ns1.example.org would
resolve to 192.168.1.2. IN A 192.168.1.1This line assigns IP address
192.168.1.1 to
the current origin, in this case example.org.www IN CNAME @The canonical name record is usually used for giving
aliases to a machine. In the example,
www is aliased to the
master machine whose name happens to be the
same as the domain name
example.org
(192.168.1.1).
CNAMEs can never be used together with another kind of
record for the same hostname.MX record IN MX 10 mail.example.org.The MX record indicates which mail servers are
responsible for handling incoming mail for the zone.
mail.example.org is
the hostname of a mail server, and 10 is the priority of
that mail server.One can have several mail servers, with priorities of
10, 20 and so on. A mail server attempting to deliver to
example.org
would first try the highest priority MX (the record with
the lowest priority number), then the second highest, etc,
until the mail can be properly delivered.For in-addr.arpa zone files (reverse
DNS), the same format is used, except
with PTR entries instead of A or CNAME.$TTL 3600
1.168.192.in-addr.arpa. IN SOA ns1.example.org. admin.example.org. (
2006051501 ; Serial
10800 ; Refresh
3600 ; Retry
604800 ; Expire
300 ) ; Negative Response TTL
IN NS ns1.example.org.
IN NS ns2.example.org.
1 IN PTR example.org.
2 IN PTR ns1.example.org.
3 IN PTR ns2.example.org.
4 IN PTR mx.example.org.
5 IN PTR mail.example.org.This file gives the proper IP
address to hostname mappings for the above fictitious
domain.It is worth noting that all names on the right side
of a PTR record need to be fully qualified (i.e., end in
a .).Caching Name ServerBINDcaching name serverA caching name server is a name server whose primary
role is to resolve recursive queries. It simply asks
queries of its own, and remembers the answers for later
use.DNSSECBINDDNS security
extensionsDomain Name System Security Extensions, or DNSSEC
for short, is a suite of specifications to protect resolving
name servers from forged DNS data, such
as spoofed DNS records. By using digital
signatures, a resolver can verify the integrity of the
record. Note that DNSSEC only provides integrity via
digitally signing the Resource Records (RRs). It provides
neither confidentiality nor protection against false
end-user assumptions. This means that it cannot protect
against people going to
example.net
instead of
example.com.
The only thing DNSSEC does is
authenticate that the data has not been compromised in
transit. The security of DNS is an
important step in securing the Internet in general. For
more in-depth details of how DNSSEC
works, the relevant RFCs are a good place
to start. See the list in
.The following sections will demonstrate how to enable
DNSSEC for an authoritative
DNS server and a recursive (or caching)
DNS server running
BIND 9. While all versions of
BIND 9 support DNSSEC,
it is necessary to have at least version 9.6.2 in order to
be able to use the signed root zone when validating
DNS queries. This is because earlier
versions lack the required algorithms to enable validation
using the root zone key. It is strongly recommended to use
the latest version of BIND 9.7 or later
to take advantage of automatic key updating for the root
key, as well as other features to automatically keep zones
signed and signatures up to date. Where configurations
differ between 9.6.2 and 9.7 and later, differences will be
pointed out.Recursive DNS Server
ConfigurationEnabling DNSSEC validation of
queries performed by a recursive DNS
server requires a few changes to
named.conf. Before making these
changes the root zone key, or trust anchor, must be
acquired. Currently the root zone key is not available in
a file format BIND understands, so it
has to be manually converted into the proper format. The
key itself can be obtained by querying the root zone for
it using dig. By
running&prompt.user; dig +multi +noall +answer DNSKEY . > root.dnskeythe key will end up in
root.dnskey. The contents should
look something like this:. 93910 IN DNSKEY 257 3 8 (
AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQ
bSEW0O8gcCjFFVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh
/RStIoO8g0NfnfL2MTJRkxoXbfDaUeVPQuYEhg37NZWA
JQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaDX6RS6CXp
oY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3
LQpzW5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGO
Yl7OyQdXfZ57relSQageu+ipAdTTJ25AsRTAoub8ONGc
LmqrAmRLKBP1dfwhYB4N7knNnulqQxA+Uk1ihz0=
) ; key id = 19036
. 93910 IN DNSKEY 256 3 8 (
AwEAAcaGQEA+OJmOzfzVfoYN249JId7gx+OZMbxy69Hf
UyuGBbRN0+HuTOpBxxBCkNOL+EJB9qJxt+0FEY6ZUVjE
g58sRr4ZQ6Iu6b1xTBKgc193zUARk4mmQ/PPGxn7Cn5V
EGJ/1h6dNaiXuRHwR+7oWh7DnzkIJChcTqlFrXDW3tjt
) ; key id = 34525Do not be alarmed if the obtained keys differ from
this example. They might have changed since these
instructions were last updated. This output actually
contains two keys. The first key in the listing, with the
value 257 after the DNSKEY record type, is the one needed.
This value indicates that this is a Secure Entry Point
(SEP),
commonly known as a Key Signing Key
(KSK). The
second key, with value 256, is a subordinate key, commonly
called a Zone Signing Key
(ZSK). More on
the different key types later in
.Now the key must be verified and formatted so that
BIND can use it. To verify the key,
generate a DS
RR set. Create
a file containing these
RRs with&prompt.user; dnssec-dsfromkey -f root.dnskey . > root.dsThese records use SHA-1 and SHA-256 respectively, and
should look similar to the following example, where the
longer is using SHA-256.. IN DS 19036 8 1
B256BD09DC8DD59F0E0F0D8541B8328DD986DF6E
. IN DS 19036 8 2 49AAC11D7B6F6446702E54A1607371607A1A41855200FD2CE1CDDE32F24E8FB5The SHA-256 RR can now be compared
to the digest in https://data.iana.org/root-anchors/root-anchors.xml.
To be absolutely sure that the key has not been tampered
with the data in the XML file should be
verified using a proper PGP signature.Next, the key must be formatted properly. This
differs a little between BIND versions
9.6.2 and 9.7 and later. In version 9.7 support was added
to automatically track changes to the key and update it as
necessary. This is done using
managed-keys as seen in the example
below. When using the older version, the key is added
using a trusted-keys statement and
updates must be done manually. For
BIND 9.6.2 the format should look
like:trusted-keys {
"." 257 3 8
"AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQbSEW0O8gcCjF
FVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh/RStIoO8g0NfnfL2MTJRkxoX
bfDaUeVPQuYEhg37NZWAJQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaD
X6RS6CXpoY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3LQpz
W5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGOYl7OyQdXfZ57relS
Qageu+ipAdTTJ25AsRTAoub8ONGcLmqrAmRLKBP1dfwhYB4N7knNnulq
QxA+Uk1ihz0=";
};For 9.7 the format will instead be:managed-keys {
"." initial-key 257 3 8
"AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQbSEW0O8gcCjF
FVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh/RStIoO8g0NfnfL2MTJRkxoX
bfDaUeVPQuYEhg37NZWAJQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaD
X6RS6CXpoY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3LQpz
W5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGOYl7OyQdXfZ57relS
Qageu+ipAdTTJ25AsRTAoub8ONGcLmqrAmRLKBP1dfwhYB4N7knNnulq
QxA+Uk1ihz0=";
};The root key can now be added to
named.conf either directly or by
including a file containing the key. After these steps,
configure BIND to do
DNSSEC validation on queries by editing
named.conf and adding the following
to the options directive:dnssec-enable yes;
dnssec-validation yes;To verify that it is actually working use
dig to make a query for a
signed zone using the resolver just configured. A
successful reply will contain the AD
flag to indicate the data was authenticated. Running a
query such as&prompt.user; dig @resolver +dnssec se ds should return the DS
RR for the .se zone.
In the flags: section the
AD flag should be set, as seen
in:...
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1
...The resolver is now capable of authenticating
DNS queries.Authoritative DNS Server
ConfigurationIn order to get an authoritative name server to serve
a DNSSEC signed zone a little more work
is required. A zone is signed using cryptographic keys
which must be generated. It is possible to use only one
key for this. The preferred method however is to have a
strong well-protected Key Signing Key
(KSK) that is
not rotated very often and a Zone Signing Key
(ZSK) that is
rotated more frequently. Information on recommended
operational practices can be found in RFC
4641: DNSSEC Operational
Practices. Practices regarding the root zone can
be found in DNSSEC
Practice Statement for the Root Zone
KSK operator and DNSSEC
Practice Statement for the Root Zone
ZSK operator. The
KSK is used to
build a chain of authority to the data in need of
validation and as such is also called a Secure Entry Point
(SEP) key. A
message digest of this key, called a Delegation Signer
(DS) record,
must be published in the parent zone to establish the
trust chain. How this is accomplished depends on the
parent zone owner. The
ZSK is used to
sign the zone, and only needs to be published
there.To enable DNSSEC for the
example.com
zone depicted in previous examples, the first step is to
use dnssec-keygen to generate
the KSK and ZSK key
pair. This key pair can utilize different cryptographic
algorithms. It is recommended to use RSA/SHA256 for the
keys and 2048 bits key length should be enough. To
generate the KSK for
example.com,
run&prompt.user; dnssec-keygen -f KSK -a RSASHA256 -b 2048 -n ZONE example.comand to generate the ZSK, run&prompt.user; dnssec-keygen -a RSASHA256 -b 2048 -n ZONE example.comdnssec-keygen outputs two
files, the public and the private keys in files named
similar to
Kexample.com.+005+nnnnn.key (public)
and Kexample.com.+005+nnnnn.private
(private). The nnnnn part of the file
name is a five digit key ID. Keep track of which key ID
belongs to which key. This is especially important when
having more than one key in a zone. It is also possible
to rename the keys. For each KSK file
do:&prompt.user; mv Kexample.com.+005+nnnnn.key Kexample.com.+005+nnnnn.KSK.key
&prompt.user; mv Kexample.com.+005+nnnnn.private Kexample.com.+005+nnnnn.KSK.privateFor the ZSK files, substitute
KSK for ZSK as
necessary. The files can now be included in the zone
file, using the $include statement. It
should look something like this:$include Kexample.com.+005+nnnnn.KSK.key ; KSK
$include Kexample.com.+005+nnnnn.ZSK.key ; ZSKFinally, sign the zone and tell
BIND to use the signed zone file. To
sign a zone dnssec-signzone is
used. The command to sign the zone
example.com,
located in example.com.db would look
similar to&prompt.user; dnssec-signzone -o example.com -k Kexample.com.+005+nnnnn.KSK example.com.db Kexample.com.+005+nnnnn.ZSK.keyThe key supplied to the argument
is the KSK and the other key file is
the ZSK that should be used in the
signing. It is possible to supply more than one
KSK and ZSK, which
will result in the zone being signed with all supplied
keys. This can be needed to supply zone data signed using
more than one algorithm. The output of
dnssec-signzone is a zone file
with all RRs signed. This output will
end up in a file with the extension
.signed, such as
example.com.db.signed. The
DS records
will also be written to a separate file
dsset-example.com. To use this
signed zone just modify the zone directive in
named.conf to use
example.com.db.signed. By default,
the signatures are only valid 30 days, meaning that the
zone needs to be resigned in about 15 days to be sure
that resolvers are not caching records with stale
signatures. It is possible to make a script and a cron
job to do this. See relevant manuals for details.Be sure to keep private keys confidential, as with all
cryptographic keys. When changing a key it is best to
include the new key into the zone, while still signing
with the old one, and then move over to using the new key
to sign. After these steps are done the old key can be
removed from the zone. Failure to do this might render
the DNS data unavailable for a time,
until the new key has propagated through the
DNS hierarchy. For more information on
key rollovers and other DNSSEC
operational issues, see RFC
4641: DNSSEC Operational
practices.Automation Using BIND 9.7 or
LaterBeginning with BIND version 9.7 a
new feature called Smart Signing was
introduced. This feature aims to make the key management
and signing process simpler by automating parts of the
task. By putting the keys into a directory called a
key repository, and using the new
option auto-dnssec, it is possible to
create a dynamic zone which will be resigned as needed.
To update this zone use
nsupdate with the new option
. rndc has
also grown the ability to sign zones with keys in the key
repository, using the option . To
tell BIND to use this automatic signing
and zone updating for example.com, add the
following to named.conf:zone example.com {
type master;
key-directory "/etc/named/keys";
update-policy local;
auto-dnssec maintain;
file "/etc/named/dynamic/example.com.zone";
};After making these changes, generate keys for the zone
as explained in , put
those keys in the key repository given as the argument to
the key-directory in the zone
configuration and the zone will be signed automatically.
Updates to a zone configured this way must be done using
nsupdate, which will take care
of re-signing the zone with the new data added. For
further details, see and the
BIND documentation.SecurityAlthough BIND is the most common implementation of
DNS, there is always the issue of
security. Possible and exploitable security holes are
sometimes found.While &os; automatically drops
named into a &man.chroot.8;
environment; there are several other security mechanisms in
place which could help to lure off possible
DNS service attacks.It is always good idea to read
CERT's
security advisories and to subscribe to the
&a.security-notifications; to stay up to date with the
current Internet and &os; security issues.If a problem arises, keeping sources up to date and
having a fresh build of named
may help.Further ReadingBIND/named manual pages:
&man.rndc.8; &man.named.8; &man.named.conf.5;
&man.nsupdate.1; &man.dnssec-signzone.8;
&man.dnssec-keygen.8;Official
ISC BIND PageOfficial
ISC BIND ForumO'Reilly
DNS and BIND 5th
EditionRoot
DNSSECDNSSEC
Trust Anchor Publication for the Root
ZoneRFC1034
- Domain Names - Concepts and FacilitiesRFC1035
- Domain Names - Implementation and
SpecificationRFC4033
- DNS Security Introduction and
RequirementsRFC4034
- Resource Records for the DNS
Security ExtensionsRFC4035
- Protocol Modifications for the
DNS Security
ExtensionsRFC4641
- DNSSEC Operational PracticesRFC
5011 - Automated Updates of DNS
Security (DNSSEC
Trust AnchorsApache HTTP ServerMurrayStokelyContributed by web serverssetting upApacheThe open source
Apache HTTP Server is the most widely
used web server. &os; does not install this web server by
default, but it can be installed from the
www/apache24 package or port.This section summarizes how to configure and start version
2.x of the Apache HTTP
Server on &os;. For more detailed information
about Apache 2.X and its
configuration directives, refer to httpd.apache.org.Configuring and Starting ApacheApacheconfiguration fileIn &os;, the main Apache HTTP
Server configuration file is installed as
/usr/local/etc/apache2x/httpd.conf,
where x represents the version
number. This ASCII text file begins
comment lines with a #. The most
frequently modified directives are:ServerRoot "/usr/local"Specifies the default directory hierarchy for the
Apache installation.
Binaries are stored in the bin and
sbin subdirectories of the server
root and configuration files are stored in the etc/apache2x
subdirectory.ServerAdmin you@example.comChange this to the email address to receive problems
with the server. This address also appears on some
server-generated pages, such as error documents.ServerName
www.example.com:80Allows an administrator to set a hostname which is
sent back to clients for the server. For example,
www can be used instead of the
actual hostname. If the system does not have a
registered DNS name, enter its
IP address instead. If the server
will listen on an alternate report, change
80 to the alternate port
number.DocumentRoot
"/usr/local/www/apache2x/data"The directory where documents will be served from.
By default, all requests are taken from this directory,
but symbolic links and aliases may be used to point to
other locations.It is always a good idea to make a backup copy of the
default Apache configuration file
before making changes. When the configuration of
Apache is complete, save the file
and verify the configuration using
apachectl. Running apachectl
configtest should return Syntax
OK.Apachestarting or stoppingTo launch Apache at system
startup, add the following line to
/etc/rc.conf:apache24_enable="YES"If Apache should be started
with non-default options, the following line may be added to
/etc/rc.conf to specify the needed
flags:apache24_flags=""If apachectl does not report
configuration errors, start httpd
now:&prompt.root; service apache24 startThe httpd service can be tested by
entering
http://localhost
in a web browser, replacing
localhost with the fully-qualified
domain name of the machine running httpd.
The default web page that is displayed is
/usr/local/www/apache24/data/index.html.The Apache configuration can be
tested for errors after making subsequent configuration
changes while httpd is running using the
following command:&prompt.root; service apache24 configtestIt is important to note that
configtest is not an &man.rc.8; standard,
and should not be expected to work for all startup
scripts.Virtual HostingVirtual hosting allows multiple websites to run on one
Apache server. The virtual hosts
can be IP-based or
name-based.
IP-based virtual hosting uses a different
IP address for each website. Name-based
virtual hosting uses the clients HTTP/1.1 headers to figure
out the hostname, which allows the websites to share the same
IP address.To setup Apache to use
name-based virtual hosting, add a
VirtualHost block for each website. For
example, for the webserver named www.domain.tld with a
virtual domain of www.someotherdomain.tld,
add the following entries to
httpd.conf:<VirtualHost *>
ServerName www.domain.tld
DocumentRoot /www/domain.tld
</VirtualHost>
<VirtualHost *>
ServerName www.someotherdomain.tld
DocumentRoot /www/someotherdomain.tld
</VirtualHost>For each virtual host, replace the values for
ServerName and
DocumentRoot with the values to be
used.For more information about setting up virtual hosts,
consult the official Apache
documentation at: http://httpd.apache.org/docs/vhosts/.Apache ModulesApachemodulesApache uses modules to augment
the functionality provided by the basic server. Refer to http://httpd.apache.org/docs/current/mod/
for a complete listing of and the configuration details for
the available modules.In &os;, some modules can be compiled with the
www/apache24 port. Type make
config within
/usr/ports/www/apache24 to see which
modules are available and which are enabled by default. If
the module is not compiled with the port, the &os; Ports
Collection provides an easy way to install many modules. This
section describes three of the most commonly used
modules.mod_sslweb serverssecureSSLcryptographyThe mod_ssl module uses the
OpenSSL library to provide strong
cryptography via the Secure Sockets Layer
(SSLv3) and Transport Layer Security
(TLSv1) protocols. This module provides
everything necessary to request a signed certificate from a
trusted certificate signing authority to run a secure web
server on &os;.In &os;, mod_ssl module is enabled
by default in both the package and the port. The available
configuration directives are explained at http://httpd.apache.org/docs/current/mod/mod_ssl.html.mod_perlmod_perlPerlThe
mod_perl module makes it possible to
write Apache modules in
Perl. In addition, the
persistent interpreter embedded in the server avoids the
overhead of starting an external interpreter and the penalty
of Perl start-up time.The mod_perl can be installed using
the www/mod_perl2 package or port.
Documentation for using this module can be found at http://perl.apache.org/docs/2.0/index.html.mod_phpTomRhodesWritten by mod_phpPHPPHP: Hypertext Preprocessor
(PHP) is a general-purpose scripting
language that is especially suited for web development.
Capable of being embedded into HTML, its
syntax draws upon C, &java;, and
Perl with the intention of
allowing web developers to write dynamically generated
webpages quickly.To gain support for PHP5 for the
Apache web server, install the
www/mod_php56 package or port. This will
install and configure the modules required to support
dynamic PHP applications. The
installation will automatically add this line to
/usr/local/etc/apache24/httpd.conf:LoadModule php5_module libexec/apache24/libphp5.soThen, perform a graceful restart to load the
PHP module:&prompt.root; apachectl gracefulThe PHP support provided by
www/mod_php56 is limited. Additional
support can be installed using the
lang/php56-extensions port which provides
a menu driven interface to the available
PHP extensions.Alternatively, individual extensions can be installed
using the appropriate port. For instance, to add
PHP support for the
MySQL database server, install
databases/php56-mysql.After installing an extension, the
Apache server must be reloaded to
pick up the new configuration changes:&prompt.root; apachectl gracefulDynamic Websitesweb serversdynamicIn addition to mod_perl and
mod_php, other languages are
available for creating dynamic web content. These include
Django and
Ruby on Rails.DjangoPythonDjangoDjango is a BSD-licensed
framework designed to allow developers to write high
performance, elegant web applications quickly. It provides
an object-relational mapper so that data types are developed
as Python objects. A rich
dynamic database-access API is provided
for those objects without the developer ever having to write
SQL. It also provides an extensible
template system so that the logic of the application is
separated from the HTML
presentation.Django depends on mod_python, and
an SQL database engine. In &os;, the
www/py-django port automatically installs
mod_python and supports the
PostgreSQL,
MySQL, or
SQLite databases, with the
default being SQLite. To change
the database engine, type make config
within /usr/ports/www/py-django, then
install the port.Once Django is installed, the
application will need a project directory along with the
Apache configuration in order to
use the embedded Python
interpreter. This interpreter is used to call the
application for specific URLs on the
site.To configure Apache to pass
requests for certain URLs to the web
application, add the following to
httpd.conf, specifying the full path to
the project directory:<Location "/">
SetHandler python-program
PythonPath "['/dir/to/the/django/packages/'] + sys.path"
PythonHandler django.core.handlers.modpython
SetEnv DJANGO_SETTINGS_MODULE mysite.settings
PythonAutoReload On
PythonDebug On
</Location>Refer to https://docs.djangoproject.com
for more information on how to use
Django.Ruby on RailsRuby on RailsRuby on Rails is another open
source web framework that provides a full development stack.
It is optimized to make web developers more productive and
capable of writing powerful applications quickly. On &os;,
it can be installed using the
www/rubygem-rails package or port.Refer to http://guides.rubyonrails.org
for more information on how to use Ruby on
Rails.File Transfer Protocol (FTP)FTP
serversThe File Transfer Protocol (FTP) provides
users with a simple way to transfer files to and from an
FTP server. &os; includes
FTP server software,
ftpd, in the base system.&os; provides several configuration files for controlling
access to the FTP server. This section
summarizes these files. Refer to &man.ftpd.8; for more details
about the built-in FTP server.ConfigurationThe most important configuration step is deciding which
accounts will be allowed access to the FTP
server. A &os; system has a number of system accounts which
should not be allowed FTP access. The list
of users disallowed any FTP access can be
found in /etc/ftpusers. By default, it
includes system accounts. Additional users that should not be
allowed access to FTP can be added.In some cases it may be desirable to restrict the access
of some users without preventing them completely from using
FTP. This can be accomplished be creating
/etc/ftpchroot as described in
&man.ftpchroot.5;. This file lists users and groups subject
to FTP access restrictions.FTPanonymousTo enable anonymous FTP access to the
server, create a user named ftp on the &os; system. Users
will then be able to log on to the
FTP server with a username of
ftp or anonymous. When prompted for
the password, any input will be accepted, but by convention,
an email address should be used as the password. The
FTP server will call &man.chroot.2; when an
anonymous user logs in, to restrict access to only the home
directory of the ftp user.There are two text files that can be created to specify
welcome messages to be displayed to FTP
clients. The contents of
/etc/ftpwelcome will be displayed to
users before they reach the login prompt. After a successful
login, the contents of
/etc/ftpmotd will be displayed. Note
that the path to this file is relative to the login
environment, so the contents of
~ftp/etc/ftpmotd would be displayed for
anonymous users.Once the FTP server has been
configured, set the appropriate variable in
/etc/rc.conf to start the service during
boot:ftpd_enable="YES"To start the service now:&prompt.root; service ftpd startTest the connection to the FTP server
by typing:&prompt.user; ftp localhostsysloglog filesFTPThe ftpd daemon uses
&man.syslog.3; to log messages. By default, the system log
daemon will write messages related to FTP
in /var/log/xferlog. The location of
the FTP log can be modified by changing the
following line in
/etc/syslog.conf:ftp.info /var/log/xferlogFTPanonymousBe aware of the potential problems involved with running
an anonymous FTP server. In particular,
think twice about allowing anonymous users to upload files.
It may turn out that the FTP site becomes
a forum for the trade of unlicensed commercial software or
worse. If anonymous FTP uploads are
required, then verify the permissions so that these files
cannot be read by other anonymous users until they have
been reviewed by an administrator.File and Print Services for µsoft.windows; Clients
(Samba)Samba serverMicrosoft Windowsfile serverWindows clientsprint serverWindows clientsSamba is a popular open source
software package that provides file and print services using the
SMB/CIFS protocol. This protocol is built
into µsoft.windows; systems. It can be added to
non-µsoft.windows; systems by installing the
Samba client libraries. The protocol
allows clients to access shared data and printers. These shares
can be mapped as a local disk drive and shared printers can be
used as if they were local printers.On &os;, the Samba client
libraries can be installed using the
net/samba-smbclient port or package. The
client provides the ability for a &os; system to access
SMB/CIFS shares in a µsoft.windows;
network.A &os; system can also be configured to act as a
Samba server by installing the
net/samba43 port or package. This allows the
administrator to create SMB/CIFS
shares on
the &os; system which can be accessed by clients running
µsoft.windows; or the Samba
client libraries.Server ConfigurationSamba is configured in
/usr/local/etc/smb4.conf. This file must
be created before Samba
can be used.A simple smb4.conf to share
directories and printers with &windows; clients in a
workgroup is shown here. For more complex setups
involving LDAP or Active Directory, it is easier to use
&man.samba-tool.8; to create the initial
smb4.conf.[global]
workgroup = WORKGROUP
server string = Samba Server Version %v
netbios name = ExampleMachine
wins support = Yes
security = user
passdb backend = tdbsam
# Example: share /usr/src accessible only to 'developer' user
[src]
path = /usr/src
valid users = developer
writable = yes
browsable = yes
read only = no
guest ok = no
public = no
create mask = 0666
directory mask = 0755Global SettingsSettings that describe the network are added in
/usr/local/etc/smb4.conf:workgroupThe name of the workgroup to be served.netbios nameThe NetBIOS name by which a
Samba server is known. By
default, it is the same as the first component of the
host's DNS name.server stringThe string that will be displayed in the output of
net view and some other
networking tools that seek to display descriptive text
about the server.wins supportWhether Samba will
act as a WINS server. Do not
enable support for WINS on more than
one server on the network.Security SettingsThe most important settings in
/usr/local/etc/smb4.conf are the
security model and the backend password format. These
directives control the options:securityThe most common settings are
security = share and
security = user. If the clients
use usernames that are the same as their usernames on
the &os; machine, user level security should be
used. This is the default security policy and it
requires clients to first log on before they can
access shared resources.In share level security, clients do not need to
log onto the server with a valid username and password
before attempting to connect to a shared resource.
This was the default security model for older versions
of Samba.passdb backendNIS+LDAPSQL databaseSamba has several
different backend authentication models. Clients may
be authenticated with LDAP, NIS+, an SQL database,
or a modified password file. The recommended
authentication method, tdbsam,
is ideal for simple networks and is covered here.
For larger or more complex networks,
ldapsam is recommended.
smbpasswd
was the former default and is now obsolete.Samba Users&os; user accounts must be mapped to the
SambaSAMAccount database for
&windows; clients to access the share.
Map existing &os; user accounts using
&man.pdbedit.8;:&prompt.root; pdbedit -a usernameThis section has only mentioned the most commonly used
settings. Refer to the Official
Samba HOWTO for additional information about the
available configuration options.Starting SambaTo enable Samba at boot time,
add the following line to
/etc/rc.conf:samba_enable="YES"To enable Samba4, use:samba_server_enable="YES"To start Samba now:&prompt.root; service samba start
Starting SAMBA: removing stale tdbs :
Starting nmbd.
Starting smbd.Samba consists of three
separate daemons. Both the nmbd
and smbd daemons are started by
samba_enable. If winbind name resolution
is also required, set:winbindd_enable="YES"Samba can be stopped at any
time by typing:&prompt.root; service samba stopSamba is a complex software
suite with functionality that allows broad integration with
µsoft.windows; networks. For more information about
functionality beyond the basic configuration described here,
refer to http://www.samba.org.Clock Synchronization with NTPNTPntpdOver time, a computer's clock is prone to drift. This is
problematic as many network services require the computers on a
network to share the same accurate time. Accurate time is also
needed to ensure that file timestamps stay consistent. The
Network Time Protocol (NTP) is one way to
provide clock accuracy in a network.&os; includes &man.ntpd.8; which can be configured to query
other NTP servers in order to synchronize the
clock on that machine or to provide time services to other
computers in the network. The servers which are queried can be
local to the network or provided by an ISP.
In addition, an online
list of publicly accessible NTP
servers is available. When choosing a public
NTP server, select one that is geographically
close and review its usage policy.Choosing several NTP servers is
recommended in case one of the servers becomes unreachable or
its clock proves unreliable. As ntpd
receives responses, it favors reliable servers over the less
reliable ones.This section describes how to configure
ntpd on &os;. Further documentation
can be found in /usr/share/doc/ntp/ in HTML
format.NTP ConfigurationNTPntp.confOn &os;, the built-in ntpd can
be used to synchronize a system's clock. To enable
ntpd at boot time, add
ntpd_enable="YES" to
/etc/rc.conf. Additional variables can
be specified in /etc/rc.conf. Refer to
&man.rc.conf.5; and &man.ntpd.8; for
details.This application reads /etc/ntp.conf
to determine which NTP servers to query.
Here is a simple example of an
/etc/ntp.conf: Sample /etc/ntp.confserver ntplocal.example.com prefer
server timeserver.example.org
server ntp2a.example.net
driftfile /var/db/ntp.driftThe format of this file is described in &man.ntp.conf.5;.
The server option specifies which servers
to query, with one server listed on each line. If a server
entry includes prefer, that server is
preferred over other servers. A response from a preferred
server will be discarded if it differs significantly from
other servers' responses; otherwise it will be used. The
prefer argument should only be used for
NTP servers that are known to be highly
accurate, such as those with special time monitoring
hardware.The driftfile entry specifies which
file is used to store the system clock's frequency offset.
ntpd uses this to automatically
compensate for the clock's natural drift, allowing it to
maintain a reasonably correct setting even if it is cut off
from all external time sources for a period of time. This
file also stores information about previous responses
from NTP servers. Since this file contains
internal information for NTP, it should not
be modified.By default, an NTP server is accessible
to any network host. The restrict option
in /etc/ntp.conf can be used to control
which systems can access the server. For example, to deny all
machines from accessing the NTP server, add
the following line to
/etc/ntp.conf:restrict default ignoreThis will also prevent access from other
NTP servers. If there is a need to
synchronize with an external NTP server,
allow only that specific server. Refer to &man.ntp.conf.5;
for more information.To allow machines within the network to synchronize their
clocks with the server, but ensure they are not allowed to
configure the server or be used as peers to synchronize
against, instead use:restrict 192.168.1.0 mask 255.255.255.0 nomodify notrapwhere 192.168.1.0 is the local
network address and 255.255.255.0 is the network's
subnet mask.Multiple restrict entries are
supported. For more details, refer to the Access
Control Support subsection of
&man.ntp.conf.5;.Once ntpd_enable="YES" has been added
to /etc/rc.conf,
ntpd can be started now without
rebooting the system by typing:&prompt.root; service ntpd startUsing NTP with a
PPP Connectionntpd does not need a permanent
connection to the Internet to function properly. However, if
a PPP connection is configured to dial out
on demand, NTP traffic should be prevented
from triggering a dial out or keeping the connection alive.
This can be configured with filter
directives in /etc/ppp/ppp.conf. For
example: set filter dial 0 deny udp src eq 123
# Prevent NTP traffic from initiating dial out
set filter dial 1 permit 0 0
set filter alive 0 deny udp src eq 123
# Prevent incoming NTP traffic from keeping the connection open
set filter alive 1 deny udp dst eq 123
# Prevent outgoing NTP traffic from keeping the connection open
set filter alive 2 permit 0/0 0/0For more details, refer to the
PACKET FILTERING section in &man.ppp.8; and
the examples in
/usr/share/examples/ppp/.Some Internet access providers block low-numbered ports,
preventing NTP from functioning since replies never reach
the machine.iSCSI Initiator and Target
ConfigurationiSCSI is a way to share storage over a
network. Unlike NFS, which works at the file
system level, iSCSI works at the block device
level.In iSCSI terminology, the system that
shares the storage is known as the target.
The storage can be a physical disk, or an area representing
multiple disks or a portion of a physical disk. For example, if
the disk(s) are formatted with ZFS, a zvol
can be created to use as the iSCSI
storage.The clients which access the iSCSI
storage are called initiators. To
initiators, the storage available through
iSCSI appears as a raw, unformatted disk
known as a LUN. Device nodes for the disk
appear in /dev/ and the device must be
separately formatted and mounted.Beginning with 10.0-RELEASE, &os; provides a native,
kernel-based iSCSI target and initiator.
This section describes how to configure a &os; system as a
target or an initiator.Configuring an iSCSI TargetThe native iSCSI target is supported
starting with &os; 10.0-RELEASE. To use
iSCSI in older versions of &os;, install
a userspace target from the Ports Collection, such as
net/istgt. This chapter only describes
the native target.To configure an iSCSI target, create
the /etc/ctl.conf configuration file, add
a line to /etc/rc.conf to make sure the
&man.ctld.8; daemon is automatically started at boot, and then
start the daemon.The following is an example of a simple
/etc/ctl.conf configuration file. Refer
to &man.ctl.conf.5; for a more complete description of this
file's available options.portal-group pg0 {
discovery-auth-group no-authentication
listen 0.0.0.0
listen [::]
}
target iqn.2012-06.com.example:target0 {
auth-group no-authentication
portal-group pg0
lun 0 {
path /data/target0-0
size 4G
}
}The first entry defines the pg0 portal
group. Portal groups define which network addresses the
&man.ctld.8; daemon will listen on. The
discovery-auth-group no-authentication
entry indicates that any initiator is allowed to perform
iSCSI target discovery without
authentication. Lines three and four configure &man.ctld.8;
to listen on all IPv4
(listen 0.0.0.0) and
IPv6 (listen [::])
addresses on the default port of 3260.It is not necessary to define a portal group as there is a
built-in portal group called default. In
this case, the difference between default
and pg0 is that with
default, target discovery is always denied,
while with pg0, it is always
allowed.The second entry defines a single target. Target has two
possible meanings: a machine serving iSCSI
or a named group of LUNs. This example
uses the latter meaning, where
iqn.2012-06.com.example:target0 is the
target name. This target name is suitable for testing
purposes. For actual use, change
com.example to the real domain name,
reversed. The 2012-06 represents the year
and month of acquiring control of that domain name, and
target0 can be any value. Any number of
targets can be defined in this configuration file.The auth-group no-authentication line
allows all initiators to connect to the specified target and
portal-group pg0 makes the target reachable
through the pg0 portal group.The next section defines the LUN. To
the initiator, each LUN will be visible as
a separate disk device. Multiple LUNs can
be defined for each target. Each LUN is
identified by a number, where LUN 0 is
mandatory. The path /data/target0-0 line
defines the full path to a file or zvol backing the
LUN. That path must exist before starting
&man.ctld.8;. The second line is optional and specifies the
size of the LUN.Next, to make sure the &man.ctld.8; daemon is started at
boot, add this line to
/etc/rc.conf:ctld_enable="YES"To start &man.ctld.8; now, run this command:&prompt.root; service ctld startAs the &man.ctld.8; daemon is started, it reads
/etc/ctl.conf. If this file is edited
after the daemon starts, use this command so that the changes
take effect immediately:&prompt.root; service ctld reloadAuthenticationThe previous example is inherently insecure as it uses
no authentication, granting anyone full access to all
targets. To require a username and password to access
targets, modify the configuration as follows:auth-group ag0 {
chap username1 secretsecret
chap username2 anothersecret
}
portal-group pg0 {
discovery-auth-group no-authentication
listen 0.0.0.0
listen [::]
}
target iqn.2012-06.com.example:target0 {
auth-group ag0
portal-group pg0
lun 0 {
path /data/target0-0
size 4G
}
}The auth-group section defines
username and password pairs. An initiator trying to connect
to iqn.2012-06.com.example:target0 must
first specify a defined username and secret. However,
target discovery is still permitted without authentication.
To require target discovery authentication, set
discovery-auth-group to a defined
auth-group name instead of
no-authentication.It is common to define a single exported target for
every initiator. As a shorthand for the syntax above, the
username and password can be specified directly in the
target entry:target iqn.2012-06.com.example:target0 {
portal-group pg0
chap username1 secretsecret
lun 0 {
path /data/target0-0
size 4G
}
}Configuring an iSCSI InitiatorThe iSCSI initiator described in this
section is supported starting with &os; 10.0-RELEASE. To
use the iSCSI initiator available in
older versions, refer to &man.iscontrol.8;.The iSCSI initiator requires that the
&man.iscsid.8; daemon is running. This daemon does not use a
configuration file. To start it automatically at boot, add
this line to /etc/rc.conf:iscsid_enable="YES"To start &man.iscsid.8; now, run this command:&prompt.root; service iscsid startConnecting to a target can be done with or without an
/etc/iscsi.conf configuration file. This
section demonstrates both types of connections.Connecting to a Target Without a Configuration
FileTo connect an initiator to a single target, specify the
IP address of the portal and the name of
the target:&prompt.root; iscsictl -A -p 10.10.10.10 -t iqn.2012-06.com.example:target0To verify if the connection succeeded, run
iscsictl without any arguments. The
output should look similar to this:Target name Target portal State
iqn.2012-06.com.example:target0 10.10.10.10 Connected: da0In this example, the iSCSI session
was successfully established, with
/dev/da0 representing the attached
LUN. If the
iqn.2012-06.com.example:target0 target
exports more than one LUN, multiple
device nodes will be shown in that section of the
output:Connected: da0 da1 da2.Any errors will be reported in the output, as well as
the system logs. For example, this message usually means
that the &man.iscsid.8; daemon is not running:Target name Target portal State
iqn.2012-06.com.example:target0 10.10.10.10 Waiting for iscsid(8)The following message suggests a networking problem,
such as a wrong IP address or
port:Target name Target portal State
iqn.2012-06.com.example:target0 10.10.10.11 Connection refusedThis message means that the specified target name is
wrong:Target name Target portal State
iqn.2012-06.com.example:target0 10.10.10.10 Not foundThis message means that the target requires
authentication:Target name Target portal State
iqn.2012-06.com.example:target0 10.10.10.10 Authentication failedTo specify a CHAP username and
secret, use this syntax:&prompt.root; iscsictl -A -p 10.10.10.10 -t iqn.2012-06.com.example:target0 -u user -s secretsecretConnecting to a Target with a Configuration
FileTo connect using a configuration file, create
/etc/iscsi.conf with contents like
this:t0 {
TargetAddress = 10.10.10.10
TargetName = iqn.2012-06.com.example:target0
AuthMethod = CHAP
chapIName = user
chapSecret = secretsecret
}The t0 specifies a nickname for the
configuration file section. It will be used by the
initiator to specify which configuration to use. The other
lines specify the parameters to use during connection. The
TargetAddress and
TargetName are mandatory, whereas the
other options are optional. In this example, the
CHAP username and secret are
shown.To connect to the defined target, specify the
nickname:&prompt.root; iscsictl -An t0Alternately, to connect to all targets defined in the
configuration file, use:&prompt.root; iscsictl -AaTo make the initiator automatically connect to all
targets in /etc/iscsi.conf, add the
following to /etc/rc.conf:iscsictl_enable="YES"
iscsictl_flags="-Aa"