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				.\" SPDX-License-Identifier: BSD-2-Clause
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				.\" Copyright (c) 2006-2019 Roy Marples
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				.Dd September 8, 2019
				.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 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.
				If
				.Ar protocol
				is
				.Ar token
				then
				.Ar algorithm is
				snd_secretid/rcv_secretid so you can send and recieve 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
				or
				.Ar 0
				which means the token never expires.
				For the token protocol,
				.Ar secretid
				needs to be 0 and
				.Ar realm
				needs to be "".
				If
				.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 @RUNDIR@/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
				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).
				This, plus the IAID will be used as the
				.Ic clientid .
				The DUID generated will be held in
				.Pa @DBDIR@/duid
				and should not be copied to other hosts.
				This file also takes precedence over the above rules.
				.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.
				If
				.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.
				If
				.Ar name
				is an empty string then the current system hostname is sent.
				If
				.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 an 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 leasetime of
				.Ar seconds .
				.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
				rather than
				.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 200 +
				.Xr if_nametoindex 3 .
				An extra 100 will be added for wireless 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 master mode.
				If
				.Nm
				cannot determine the carrier state,
				.Nm
				will enter a tight polling loop until the interface is marked up and running
				or a valid carrier state is reported.
				.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
				If
				.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
				and moving from DISCOVER to IPv4LL if no reply.
				The default is 5 seconds.
				A setting of 0 seconds causes
				.Nm dhcpcd
				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.
				.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 @SCRIPT@ .
				.It Ic ssid Ar ssid
				Subsequent options are only parsed for this wireless
				.Ar ssid .
				.It Ic slaac Op Ar hwaddr \| Ar private
				Selects the interface identifier used for SLAAC generated IPv6 addresses.
				If
				.Ar private
				is used, an RFC 7217 address is generated.
				.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.
				If
				.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 messages with the userclass.
				You can specify more than one.
				.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
				or
				.Ic vendopt
				directive.
				This can optionally be followed by both
				.Ic embed
				or
				.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
				of
				.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
				of
				.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
				of
				.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 @DBDIR@/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