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.Dd August 23, 2021

.Dt DHCPCD.CONF 5

.Os

.Sh NAME

.Nm dhcpcd.conf

.Nd dhcpcd configuration file

.Sh DESCRIPTION

Although

.Nm dhcpcd

can do everything from the command line, there are cases where it's just easier

to do it once in a configuration file.

Most of the options found in

.Xr dhcpcd 8

can be used here.

The first word on the line is the option and the rest of the line is the value.

Leading and trailing whitespace for the option and value are trimmed.

You can escape characters in the value using the \\ character.

Comments can be prefixed with the # character.

String values should be quoted with the " character.

.Pp

Here's a list of available options:

.Bl -tag -width indent

.It Ic allowinterfaces Ar pattern

When discovering interfaces, the interface name must match

.Ar pattern

which is a space or comma separated list of patterns passed to

.Xr fnmatch 3 .

If the same interface is matched in

.Ic denyinterfaces

then it is still denied.

.It Ic denyinterfaces Ar pattern

When discovering interfaces, the interface name must not match

.Ar pattern

which is a space or comma separated list of patterns passed to

.Xr fnmatch 3 .

.It Ic anonymous

Enables Anonymity Profiles for DHCP, RFC 7844.

Any DUID is ignored and ClientID is set to LL only.

All non essential options are then masked at this point,

but they could be unmasked by explicitly requesting the option

.Sy after

the

.Ic anonymous

option is processed.

As such, the

.Ic anonymous

option

.Sy should

be the last option in the configuration unless you really want to

send something which could identify you.

.Nm dhcpcd

will not try and reboot an old lease, it will go straight into

DISCOVER/SOLICIT.

.It Ic randomise_hwaddr

Forces a hardware address randomisation when the interface is brought up

or when the carrier is lost.

This is generally used in tandem with the anonymous option.

.It Ic arping Ar address Op address

.Nm dhcpcd

will arping each address in order before attempting DHCP.

If an address is found, we will select the replying hardware address as the

profile, otherwise the IP address.

Example:

.Pp

.D1 interface bge0

.D1 arping 192.168.0.1

.Pp

.D1 # My specific 192.168.0.1 network

.D1 profile dd:ee:aa:dd:bb:ee

.D1 static ip_address=192.168.0.10/24

.Pp

.D1 # A generic 192.168.0.1 network

.D1 profile 192.168.0.1

.D1 static ip_address=192.168.0.98/24

.It Ic authprotocol Ar protocol Op Ar algorithm Op Ar rdm

Authenticate DHCP messages.

See the Supported Authentication Protocols section.

.Ar protocol

.Ar token

then

.Ar algorithm is

snd_secretid/rcv_secretid so you can send and receive different tokens.

.It Ic authtoken Ar secretid Ar realm Ar expire Ar key

Define a shared key for use in authentication.

.Ar realm

can be "" to for use with the

.Ar delayed

protocol.

.Ar expire

is the date the token expires and should be formatted "yyy-mm-dd HH:MM".

You can use the keyword

.Ar forever

.Ar 0

which means the token never expires.

For the token protocol,

.Ar secretid

needs to be 0 and

.Ar realm

needs to be "".

.Nm dhcpcd

has the error

.D1 dhcp_auth_encode: Invalid argument

then it means that

.Nm dhcpcd

could not find the correct authentication token in your configuration.

.It Ic background

Fork to the background immediately.

This is useful for startup scripts which don't disable link messages for

carrier status.

.It Ic blacklist Ar address Ns Op /cidr

Ignores all packets from

.Ar address Ns Op /cidr .

.It Ic whitelist Ar address Ns Op /cidr

Only accept packets from

.Ar address Ns Op /cidr .

.Ic blacklist

is ignored if

.Ic whitelist

is set.

.It Ic bootp

Be a BOOTP client.

Basically, this just doesn't send a DHCP Message Type option and will only

interact with a BOOTP server.

All other DHCP options still work.

.It Ic broadcast

Instructs the DHCP server to broadcast replies back to the client.

Normally this is only set for non-Ethernet interfaces,

such as FireWire and InfiniBand.

In most cases,

.Nm dhcpcd

will set this automatically.

.It Ic controlgroup Ar group

Sets the group ownership of

.Pa /var/run/dhcpcd/sock

so that users other than root can connect to

.Nm dhcpcd .

.It Ic debug

Echo debug messages to the stderr and syslog.

.It Ic dev Ar value

Load the

.Ar value

.Pa /dev

management module.

.Nm dhcpcd

will load the first one found to work, if any.

.It Ic env Ar value

Push

.Ar value

to the environment for use in

.Xr dhcpcd-run-hooks 8 .

For example, you can force the hostname hook to always set the hostname with

.Ic env

.Va force_hostname=YES .

Or set which driver

.Xr wpa_supplicant 8

should use with

.Ic env

.Va wpa_supplicant_driver=nl80211

.Pp

If the hostname is set, it will be will set to the FQDN if possible as per

RFC 4702, section 3.1.

If the FQDN option is missing,

.Nm dhcpcd

will still try and set a FQDN from the hostname and domain options for

consistency.

To override this, set

.Ic env

.Va hostname_fqdn=[YES|NO|SERVER] .

A value of

.Va SERVER

means just what the server says, don't manipulate it.

This could lead to an inconsistent hostname on a DHCPv4 and DHCPv6 network

where the DHCPv4 hostname is short and the DHCPv6 has an FQDN.

DHCPv6 has no hostname option.

.It Ic clientid Ar string

Send the

.Ar clientid .

If the string is of the format 01:02:03 then it is encoded as hex.

For interfaces whose hardware address is longer than 8 bytes, or if the

.Ar clientid

is an empty string then

.Nm dhcpcd

sends a default

.Ar clientid

of the hardware family and the hardware address.

.It Ic duid Op ll | lt | uuid | value

Use a DHCP Unique Identifier.

If a system UUID is available, that will be used to create a DUID-UUID,

otheriwse if persistent storage is available then a DUID-LLT

(link local address + time) is generated,

otherwise DUID-LL is generated (link local address).

The DUID type can be hinted as an optional parameter if the file

.Pa /var/db/dhcpcd/duid

does not exist.

If not

.Va ll ,

.Va lt

.Va uuid

then

.Va value

will be converted from 00:11:22:33 format.

This, plus the IAID will be used as the

.Ic clientid .

The DUID generated will be held in

.Pa /var/db/dhcpcd/duid

and should not be copied to other hosts.

This file also takes precedence over the above rules except for setting a value.

.It Ic iaid Ar iaid

Set the Interface Association Identifier to

.Ar iaid .

This option must be used in an

.Ic interface

block.

This defaults to the VLANID (prefixed with 0xff) for the interface if set,

otherwise the last 4 bytes of the hardware address assigned to the

interface.

Each instance of this should be unique within the scope of the client and

.Nm dhcpcd

warns if a conflict is detected.

If there is a conflict, it is only a problem if the conflicted IAIDs are

used on the same network.

.It Ic dhcp

Enable DHCP on the interface, on by default.

.It Ic dhcp6

Enable DHCPv6 on the interface, on by default.

.It Ic ipv4

Enable IPv4 on the interface, on by default.

.It Ic ipv6

Enable IPv6 on the interface, on by default.

.It Ic request Op Ar address

Request the

.Ar address

in the DHCP DISCOVER message.

There is no guarantee this is the address the DHCP server will actually give.

If no

.Ar address

is given then the first address currently assigned to the

.Ar interface

is used.

.It Ic inform Op Ar address Ns Op Ar /cidr Ns Op Ar /broadcast_address

Behaves like

.Ic request

as above, but sends a DHCP INFORM instead of DISCOVER/REQUEST.

This does not get a lease as such, just notifies the DHCP server of the

.Ar address

in use.

You should also include the optional

.Ar cidr

network number in case the address is not already configured on the interface.

.Nm dhcpcd

remains running and pretends it has an infinite lease.

.Nm dhcpcd

will not de-configure the interface when it exits.

.Nm dhcpcd

fails to contact a DHCP server then it returns a failure instead of falling

back on IPv4LL.

.It Ic inform6

Performs a DHCPv6 Information Request.

No address is requested or specified, but all other DHCPv6 options are allowed.

This is normally performed automatically when an IPv6 Router Advertisement

indicates that the client should perform this operation.

This option is only needed when

.Nm dhcpcd

is not processing IPv6 RA messages and the need for a DHCPv6 Information Request

exists.

.It Ic persistent

.Nm dhcpcd

normally de-configures the interface and configuration when it exits.

Sometimes, this isn't desirable if, for example, you have root mounted over

NFS or SSH clients connect to this host and they need to be notified of

the host shutting down.

You can use this option to stop this from happening.

.It Ic fallback Ar profile

Fall back to using this profile if DHCP fails.

This allows you to configure a static profile instead of using ZeroConf.

.It Ic hostname Ar name

Sends the hostname

.Ar name

to the DHCP server so it can be registered in DNS.

.Ar name

is an empty string then the current system hostname is sent.

.Ar name

is a FQDN (i.e., contains a .) then it will be encoded as such.

.It Ic hostname_short

Sends the short hostname to the DHCP server instead of the FQDN.

This is useful because DHCP servers will not register the FQDN in their

DNS if the domain part does not match theirs.

.Pp

Also, see the

.Ic env

option above to control how the hostname is set on the host.

.It Ic ia_na Op Ar iaid Op / address

Request a DHCPv6 Normal Address for

.Ar iaid .

.Ar iaid

defaults to the

.Ic iaid

option as described above.

You can request more than one ia_na by specifying a unique

.Ar iaid

for each one.

.It Ic ia_ta Op Ar iaid

Request a DHCPv6 Temporary Address for

.Ar iaid .

You can request more than one ia_ta by specifying a unique

.Ar iaid

for each one.

.It Ic ia_pd Op Ar iaid Oo / Ar prefix / Ar prefix_len Oc Op Ar interface Op / Ar sla_id Op / Ar prefix_len Op / Ar suffix

Request a DHCPv6 Delegated Prefix for

.Ar iaid .

This option must be used in an

.Ic interface

block.

Unless a

.Ar sla_id

of 0 is assigned with the same resultant prefix length as the delegation,

a reject route is installed for the Delegated Prefix to

stop unallocated addresses being resolved upstream.

If no

.Ar interface

is given then we will assign a prefix to every other interface with a

.Ar sla_id

equivalent to the interface index assigned by the OS.

Otherwise addresses are only assigned for each

.Ar interface

and

.Ar sla_id .

Each assigned address will have a

.Ar suffix ,

defaulting to 1.

If the

.Ar suffix

is 0 then a SLAAC address is assigned.

You cannot assign a prefix to the requesting interface unless the

DHCPv6 server supports the

.Li RFC 6603

Prefix Exclude Option.

.Nm dhcpcd

has to be running for all the interfaces it is delegating to.

A default

.Ar prefix_len

of 64 is assumed, unless the maximum

.Ar sla_id

does not fit.

In this case

.Ar prefix_len

is increased to the highest multiple of 8 that can accommodate the

.Ar sla_id .

.Ar sla_id

is an integer which must be unique inside the

.Ar iaid

and is added to the prefix which must fit inside

.Ar prefix_len

less the length of the delegated prefix.

You can specify multiple

.Ar interface /

.Ar sla_id /

.Ar prefix_len

per

.Ic ia_pd ,

space separated.

IPv6RS should be disabled globally when requesting a Prefix Delegation.

.Pp

In the following example eth0 is the externally facing interface to be

configured for both IPv4 and IPv6.

The DHCPv4 server will provide us with an IPv4 address and a default route.

The DHCPv6 server is going to provide us with an IPv6 address, a default

route and a /64 subnet to be delegated to the internal interface.

The eth1 interface will be automatically configured

for IPv6 using the first address (::1) from the delegated prefix.

A second prefix is requested and assigned to two other interfaces.

.Xr rtadvd 8

can be used with an empty configuration file on eth1, eth2 and eth3,

to provide automatic

IPv6 address configuration for the internal network.

.Bd -literal

noipv6rs # disable routing solicitation

denyinterfaces eth2 # Don't touch eth2 at all

interface eth0

ipv6rs # enable routing solicitation for eth0

ia_na 1 # request an IPv6 address

ia_pd 2 eth1/0 # request a PD and assign it to eth1

ia_pd 3 eth2/1 eth3/2 # req a PD and assign it to eth2 and eth3

.Ed

.It Ic ipv4only

Only configure IPv4.

.It Ic ipv6only

Only configure IPv6.

.It Ic fqdn Op disable | none | ptr | both

.Ar none

will not ask the DHCP server to update DNS.

.Ar ptr

just asks the DHCP server to update the PTR

record of the host in DNS, whereas

.Ar both

also updates the A record.

.Ar disable

will disable the FQDN option.

The default is

.Ar both .

.Nm dhcpcd

itself never does any DNS updates.

.Nm dhcpcd

encodes the FQDN hostname as specified in

.Li RFC 1035 .

.It Ic interface Ar interface

Subsequent options are only parsed for this

.Ar interface .

.It Ic ipv6ra_autoconf

Generate SLAAC addresses for each Prefix advertised by an IPv6

Router Advertisement message with the Auto flag set.

On by default.

.It Ic ipv6ra_noautoconf

Disables the above option.

.It Ic ipv6ra_fork

By default, when

.Nm dhcpcd

receives an IPv6 Router Advertisement,

.Nm dhcpcd

will only fork to the background if the RA contains at least one unexpired

RDNSS option and a valid prefix or no DHCPv6 instruction.

Set this option so to make

.Nm dhcpcd

always fork on a RA.

.It Ic ipv6rs

Enables IPv6 Router Advertisement solicitation.

This is on by default, but is documented here in the case where it is disabled

globally but needs to be enabled for one interface.

.It Ic leasetime Ar seconds

Request a lease time of

.Ar seconds .

.Ar -1

represents an infinite lease time.

By default

.Nm dhcpcd

does not request any lease time and leaves it in the hands of the

DHCP server.

.It Ic link_rcvbuf Ar size

Override the size of the link receive buffer from the kernel default.

While

.Nm dhcpcd

will recover from link buffer overflows,

this may not be desirable on heavily loaded systems.

.It Ic logfile Ar logfile

Writes to the specified

.Ar logfile .

.Nm dhcpcd

still writes to

.Xr syslog 3 .

The

.Ar logfile

is reopened when

.Nm dhcpcd

receives the

.Dv SIGUSR2

signal.

.It Ic metric Ar metric

Metrics are used to prefer an interface over another one, lowest wins.

.Nm dhcpcd

will supply a default metric of 1000 +

.Xr if_nametoindex 3 .

This will be offset by 2000 for wireless interfaces, with additional offsets

of 1000000 for IPv4LL and 2000000 for roaming interfaces.

.It Ic mudurl Ar url

Specifies the URL for a Manufacturer Usage Description (MUD).

The description is used by upstream network devices to instantiate any

desired access lists.

See draft-ietf-opsawg-mud for more information.

.It Ic noalias

Any pre-existing IPv4 addresses will be removed from the interface when

adding a new IPv4 address.

.It Ic noarp

Don't send any ARP requests.

This also disables IPv4LL.

.It Ic noauthrequired

Don't require authentication even though we requested it.

Also allows FORCERENEW and RECONFIGURE messages without authentication.

.It Ic nodelay

Don't delay for an initial randomised time when starting protocols.

.It Ic nodev

Don't load

.Pa /dev

management modules.

.It Ic nodhcp

Don't start DHCP or listen to DHCP messages.

This is only useful when allowing IPv4LL.

.It Ic nodhcp6

Don't start DHCPv6 or listen to DHCPv6 messages.

Normally DHCPv6 is started by an IPv6 Router Advertisement instruction or

configuration.

.It Ic nogateway

Don't install any default routes.

.It Ic gateway

Install a default route if available (default).

.It Ic nohook Ar script

Don't run this hook script.

Matches full name, or prefixed with 2 numbers optionally ending with

.Pa .sh .

.Pp

So to stop

.Nm dhcpcd

from touching your DNS settings or starting wpa_supplicant you would do:-

.D1 nohook resolv.conf, wpa_supplicant

.It Ic noipv4

Don't attempt to configure an IPv4 address.

.It Ic noipv4ll

Don't attempt to obtain an IPv4LL address if we failed to get one via DHCP.

See

.Rs

.%T "RFC 3927"

.Re

.It Ic noipv6

Don't solicit or accept IPv6 Router Advertisements and DHCPv6.

.It Ic noipv6rs

Don't solicit or accept IPv6 Router Advertisements.

.It Ic nolink

Don't receive link messages about carrier status.

You should only set this for buggy interface drivers.

.It Ic noup

Don't bring the interface up when in manager mode.

.It Ic option Ar option

Requests the

.Ar option

from the server.

It can be a variable to be used in

.Xr dhcpcd-run-hooks 8

or the numerical value.

You can specify more

.Ar option Ns s

separated by commas, spaces or more

.Ic option

lines.

Prepend dhcp6_ to

.Ar option

to request a DHCPv6 option.

If no DHCPv6 options are configured,

then DHCPv4 options are mapped to equivalent DHCPv6 options.

.Pp

Prepend nd_ to

.Ar option

to handle ND options, but this only works for the

.Ic nooption ,

.Ic reject

and

.Ic require

options.

.Pp

To see a list of options you can use, call

.Nm dhcpcd

with the

.Fl V , Fl Fl variables

argument.

.It Ic nooption Ar option

Remove the option from the message before it's processed.

.It Ic require Ar option

Requires the

.Ar option

to be present in all messages, otherwise the message is ignored.

To enforce that

.Nm dhcpcd

only responds to DHCP servers and not BOOTP servers, you can

.Ic require

.Ar dhcp_message_type .

This isn't an exact science though because a BOOTP server can send DHCP-like

options.

.It Ic reject Ar option

Reject a message that contains the

.Ar option .

This is useful when you cannot use

.Ic require

to select / de-select BOOTP messages.

.It Ic destination Ar option

.Nm

detects an address added to a point to point interface (PPP, TUN, etc) then

it will set the listed DHCP options to the destination address of the

interface.

.It Ic profile Ar name

Subsequent options are only parsed for this profile

.Ar name .

.It Ic quiet

Suppress any dhcpcd output to the console, except for errors.

.It Ic reboot Ar seconds

Allow

.Ar reboot

seconds before moving to the DISCOVER phase if we have an old lease to use.

Allow

.Ar reboot

seconds before starting fallback states from the DISCOVER phase.

IPv4LL is started when the first

.Ar reboot

timeout is reached.

The default is 5 seconds.

A setting of 0 seconds causes

.Nm

to skip the reboot phase and go straight into DISCOVER.

This is desirable for mobile users because if you change from network A to

network B and they use the same subnet and the address from network A isn't

in use on network B, then the DHCP server will remain silent even if

authoritative which means

.Nm dhcpcd

will timeout before moving back to the DISCOVER phase.

This has no effect on DHCPv6 other than skipping the reboot phase.

.It Ic release

.Nm dhcpcd

will release the lease prior to stopping the interface.

.It Ic script Ar script

Use

.Ar script

instead of the default

.Pa /libexec/dhcpcd-run-hooks .

.It Ic ssid Ar ssid

Subsequent options are only parsed for this wireless

.Ar ssid .

.It Ic slaac Ar hwaddr | Ar private Op Ar temp | Ar temporary

Selects the interface identifier used for SLAAC generated IPv6 addresses.

.Ar private

is used, a RFC 7217 address is generated.

The

.Ar temporary

directive will create a temporary address for the prefix as well.

.It Ic static Ar value

Configures a static

.Ar value .

If you set

.Ic ip_address

then

.Nm dhcpcd

will not attempt to obtain a lease and will just use the value for the address

with an infinite lease time.

If you set

.Ic ip6_address ,

.Nm dhcpcd

will continue auto-configuration as normal.

.Pp

Here is an example which configures two static address, overriding the default

IPv4 broadcast address, an IPv4 router, DNS and disables IPv6 auto-configuration.

You could also use the

.Ic inform6

command here if you wished to obtain more information via DHCPv6.

For IPv4, you should use the

.Ic inform Ar ipaddress

option instead of setting a static address.

.D1 interface eth0

.D1 noipv6rs

.D1 static ip_address=192.168.0.10/24

.D1 static broadcast_address=192.168.0.63

.D1 static ip6_address=fd51:42f8:caae:d92e::ff/64

.D1 static routers=192.168.0.1

.D1 static domain_name_servers=192.168.0.1 fd51:42f8:caae:d92e::1

.Pp

Here is an example for PPP which gives the destination a default route.

It uses the special

.Ar destination

keyword to insert the destination address

into the value.

.D1 interface ppp0

.D1 static ip_address=

.D1 destination routers

.It Ic timeout Ar seconds

Time out after

.Ar seconds ,

instead of the default 30.

A setting of 0

.Ar seconds

causes

.Nm dhcpcd

to wait forever to get a lease.

.Nm dhcpcd

is working on a single interface then

.Nm dhcpcd

will exit when a timeout occurs, otherwise

.Nm dhcpcd

will fork into the background.

If using IPv4LL then

.Nm dhcpcd

start the IPv4LL process after the timeout and then wait a little longer

before really timing out.

.It Ic userclass Ar string

Tag the DHCPv4 message with the userclass.

You can specify more than one.

.It Ic msuserclass Ar string

Tag the DHCPv4 mesasge with the Microsoft userclass.

Unlike the

.Ic userclass

option, this one can only be added once.

It should only be used for Microsoft DHCP servers and the

.Ic vendorclassid

should be set to "MSFT 98" or "MSFT 5.0".

This option is not RFC compliant.

.It Ic vendor Ar code , Ns Ar value

Add an encapsulated vendor option.

.Ar code

should be between 1 and 254 inclusive.

To add a raw vendor string, omit

.Ar code

but keep the comma.

Examples.

.Pp

Set the vendor option 01 with an IP address.

.D1 vendor 01,192.168.0.2

Set the vendor option 02 with a hex code.

.D1 vendor 02,01:02:03:04:05

Set the vendor option 03 with an IP address as a string.

.D1 vendor 03,\e"192.168.0.2\e"

Set un-encapsulated vendor option to hello world.

.D1 vendor ,"hello world"

.It Ic vendorclassid Ar string

Set the DHCP Vendor Class.

DHCPv6 has its own option as shown below.

The default is

dhcpcd-<version>:<os>:<machine>:<platform>.

For example

.D1 dhcpcd-5.5.6:NetBSD-6.99.5:i386:i386

If not set then none is sent.

Some badly configured DHCP servers reject unknown vendorclassids.

To work around it, try and impersonate Windows by using the MSFT vendorclassid.

.It Ic vendclass Ar en Ar data

Add the DHCPv6 Vendor Indetifying Vendor Class with the IANA assigned Enterprise

Number

.Ar en

with the

.Ar data .

This option can be set more than once to add more data, but the behaviour,

as per RFC 3925 is undefined if the Enterprise Number differs.

.It Ic waitip Op 4 | 6

Wait for an address to be assigned before forking to the background.

4 means wait for an IPv4 address to be assigned.

6 means wait for an IPv6 address to be assigned.

If no argument is given,

.Nm

will wait for any address protocol to be assigned.

It is possible to wait for more than one address protocol and

.Nm

will only fork to the background when all waiting conditions are satisfied.

.It Ic xidhwaddr

Use the last four bytes of the hardware address as the DHCP xid instead

of a randomly generated number.

.El

.Ss Defining new options

DHCP, ND and DHCPv6 allow for the use of custom options, and RFC 3925 vendor

options for DHCP can also be supplied.

Each option needs to be started with the

.Ic define ,

.Ic definend ,

.Ic define6

.Ic vendopt

directive.

This can optionally be followed by both

.Ic embed

.Ic encap

options.

Both can be specified more than once and

.Ic embed

must come before

.Ic encap .

.Bl -tag -width indent

.It Ic define Ar code Ar type Ar variable

Defines the DHCP option

.Ar code

.Ar type

with a name of

.Ar variable

exported to

.Xr dhcpcd-run-hooks 8 .

.It Ic definend Ar code Ar type Ar variable

Defines the ND option

.Ar code

.Ar type

with a name of

.Ar variable

exported to

.Xr dhcpcd-run-hooks 8 ,

with a prefix of

.Va nd_ .

.It Ic define6 Ar code Ar type Ar variable

Defines the DHCPv6 option

.Ar code

.Ar type

with a name of

.Ar variable

exported to

.Xr dhcpcd-run-hooks 8 ,

with a prefix of

.Va dhcp6_ .

.It Ic vendopt Ar code Ar type Ar variable

Defines the Vendor-Identifying Vendor Options.

The

.Ar code

is the IANA Enterprise Number which will uniquely describe the encapsulated

options.

.Ar type

is normally

.Ar encap .

.Ar variable

names the Vendor option to be exported.

.It Ic embed Ar type Ar variable

Defines an embedded variable within the defined option.

The length is determined by the

.Ar type .

If the

.Ar variable

is not the same as defined in the parent option,

it is prefixed with the parent

.Ar variable

first with an underscore.

If the

.Ar variable

has the name of

.Ar reserved

then it is not processed.

.It Ic encap Ar code Ar type Ar variable

Defines an encapsulated variable within the defined option.

The length is determined by the

.Ar type .

If the

.Ar variable

is not the same as defined in the parent option,

it is prefixed with the parent

.Ar variable

first with an underscore.

.El

.Ss Type prefix

These keywords come before the type itself, to describe it more fully.

You can use more than one, but they must appear in the order listed below.

.Bl -tag -width -indent

.It Ic request

Requests the option by default without having to be specified in user

configuration.

.It Ic norequest

This option cannot be requested, regardless of user configuration.

.It Ic optional

This option is optional.

Only makes sense for embedded options like the client FQDN option, where

the FQDN string itself is optional.

.It Ic index

The option can appear more than once and will be indexed.

.It Ic array

The option data is split into a space separated array, each element being

the same type.

.El

.Ss Types to define

The type directly affects the length of data consumed inside the option.

Any remaining data is normally discarded.

Lengths can be specified for string and binhex types, but this is generally

with other data embedded afterwards in the same option.

.Bl -tag -width indent

.It Ic ipaddress

An IPv4 address, 4 bytes.

.It Ic ip6address

An IPv6 address, 16 bytes.

.It Ic string Op : Ic length

A NVT ASCII string of printable characters.

.It Ic byte

A byte.

.It Ic bitflags : Ic flags

A byte represented as a string of flags, most significant bit first.

For example, using ABCDEFGH then A would equal 10000000, B 01000000,

C 00100000, etc.

If the bit is not set, the flag is not printed.

A flag of 0 is not printed even if the bit position is set.

This is to allow reservation of the first bits while assigning the last bits.

.It Ic int16

A signed 16bit integer, 2 bytes.

.It Ic uint16

An unsigned 16bit integer, 2 bytes.

.It Ic int32

A signed 32bit integer, 4 bytes.

.It Ic uint32

An unsigned 32bit integer, 4 bytes.

.It Ic flag

A fixed value (1) to indicate that the option is present, 0 bytes.

.It Ic domain

An RFC 3397 encoded string.

.It Ic dname

An RFC 1035 validated string.

.It Ic binhex Op : Ic length

Binary data expressed as hexadecimal.

.It Ic embed

Contains embedded options (implies encap as well).

.It Ic encap

Contains encapsulated options (implies embed as well).

.It Ic option

References an option from the global definition.

.El

.Ss Example definition

.D1 # DHCP option 81, Fully Qualified Domain Name, RFC 4702

.D1 define 81 embed fqdn

.D1 embed byte flags

.D1 embed byte rcode1

.D1 embed byte rcode2

.D1 embed domain fqdn

.Pp

.D1 # DHCP option 125, Vendor Specific Information Option, RFC 3925

.D1 define 125 encap vsio

.D1 embed uint32 enterprise_number

.D1 # Options defined for the enterprise number

.D1 encap 1 ipaddress ipaddress

.Ss Supported Authentication Protocols

.Bl -tag -width -indent

.It Ic token

Sends a plain text token the server expects and matches a token sent by

the server.

The tokens do not have to be the same.

If unspecified, the token with a

.Ar secretid

of 0 will be used in sending messages

and validating received messages.

.It Ic delayedrealm

Delayed Authentication.

.Nm dhcpcd

will send an authentication option with no key or MAC.

The server will see this option, and select a key for

.Nm , writing the

.Ar realm

and

.Ar secretid

in it.

.Nm dhcpcd

will then look for an unexpired token with a matching

.Ar realm

and

.Ar secretid .

This token is used to authenticate all other messages.

.It Ic delayed

Same as above, but without a realm.

.El

.Ss Supported Authentication Algorithms

If none specified,

.Ic hmac-md5

is the default.

.Bl -tag -width -indent

.It Ic hmac-md5

.El

.Ss Supported Replay Detection Mechanisms

If none specified,

.Ic monotonic

is the default.

If this is changed from what was previously used,

or the means of calculating or storing it is broken, then the DHCP server

will probably have to have its notion of the client's Replay Detection Value

reset.

.Bl -tag -width -indent

.It Ic monocounter

Read the number in the file

.Pa /var/db/dhcpcd/dhcpcd-rdm.monotonic

and add one to it.

.It Ic monotime

Create an NTP timestamp from the system time.

.It Ic monotonic

Same as

.Ic monotime .

.El

.Sh SEE ALSO

.Xr fnmatch 3 ,

.Xr if_nametoindex 3 ,

.Xr dhcpcd 8 ,

.Xr dhcpcd-run-hooks 8

.Sh AUTHORS

.An Roy Marples Aq Mt roy@marples.name

.Sh BUGS

Please report them to

.Lk http://roy.marples.name/projects/dhcpcd

pauamma_gundo.comUnsubmitted

Done

Please report them to

- .Lk http://roy.marples.name/projects/dhcpcd

+ .Lk https://roy.marples.name/projects/dhcpcd

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