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DHCPCD.CONF(5)		    BSD File Formats Manual		DHCPCD.CONF(5)

     dhcpcd.conf — dhcpcd configuration file

     Although 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 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.

     Blank lines and lines starting with # are ignored.

     Here's a list of available options:

     allowinterfaces pattern
	     When discovering interfaces, the interface name must match
	     pattern which is a space or comma separated list of patterns
	     passed to fnmatch(3).  If the same interface is matched in
	     denyinterfaces then it is still denied.

     denyinterfaces pattern
	     When discovering interfaces, the interface name must not match
	     pattern which is a space or comma separated list of patterns
	     passed to fnmatch(3).

     arping address [address]
	     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:

		   interface bge0

		   static ip_address=

     authprotocol protocol algorithm rdm
	     Authenticate DHCP messages.  See the Supported Protocols section.

     authtoken secretid realm expire key
	     Define a shared key for use in authentication.  realm can be  to
	     for use with the delayed prptocol.	 expire is the date the token
	     expires and should be formatted "yyy-mm-dd HH:MM".	 You can use
	     the keyword forever or 0 which means the token never expires.

	     Background immediately.  This is useful for startup scripts which
	     don't disable link messages for carrier status.

     blacklist address[/cidr]
	     Ignores all packets from address[/cidr].

     whitelist address[/cidr]
	     Only accept packets from address[/cidr].  blacklist is ignored if
	     whitelist is set.

	     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, dhcpcd will set
	     this automatically.

     dev value
	     Load the value /dev management module.  dhcpcd will load the
	     first one found to work, if any.

     env value
	     Push value to the environment for use in dhcpcd-run-hooks(8).
	     For example, you can force the hostname hook to always set the
	     hostname with env force_hostname=YES.

	     If the hostname is set, will be will set to the FQDN if possible
	     as per RFC 4702 section 3.1.  If the FQDN option is missing,
	     dhcpcd will still try and set a FQDN from the hostname and domain
	     options for consistency.  To override this, set env
	     hostname_fqdn=[YES|NO|SERVER].  A value of 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.

     clientid string
	     Send the 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 clientid is an empty string then
	     dhcpcd sends a default clientid of the hardware family and the
	     hardware address.

     duid    Generate an RFC 4361.  compliant DHCP Unique Identifier.  If per‐
	     sistent 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 clientid.  The
	     DUID-LLT generated will be held in /etc/dhcpcd.duid and should
	     not be copied to other hosts.

     iaid iaid
	     Set the Interface Association Identifier to iaid.	This option
	     must be used in an interface block.  This defaults to 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 dhcpcd warns if a conflict is detected.  If there is a con‐
	     flict, it is only a problem if the conflicted IAIDs are used on
	     the same network.

	     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.

     fallback profile
	     Fallback to using this profile if DHCP fails.  This allows you to
	     configure a static profile instead of using ZeroConf.

     hostname name
	     Sends hostname to the DHCP server so it can be registered in DNS.
	     If hostname is an empty string then the current system hostname
	     is sent.  If hostname is a FQDN (ie, contains a .) then it will
	     be encoded as such.

	     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.

	     Also, see the env option above to control how the hostname is set
	     on the host.

     ia_na [iaid]
	     Request a DHCPv6 Normal Address for iaid.	iaid defaults to the
	     iaid option as described above.  You can request more than one
	     ia_na by specifying a unique iaid for each one.

     ia_ta [iaid]
	     Request a DHCPv6 Temporary Address for iaid.  You can request
	     more than one ia_ta by specifying a unique iaid for each one.

     ia_pd [iaid [interface [/ sla_id [/ prefix_len]]]]
	     Request a DHCPv6 Delegated Prefix for iaid.  This option must be
	     used in an interface block.  If no interface is given then we
	     will assign a prefix to every other interface with a unique
	     sla_id for each, starting from 0.	Otherwise addresses are only
	     assigned for each interface and sla_id.  You cannot assign a pre‐
	     fix to the requesting interface.  dhcpcd has to be running for
	     all the interfaces it is delegating to.  A default prefix_len of
	     64 is assumed.  sla_id is an integer and is added to the prefix
	     which must fit inside prefix_len less the length of the delegated
	     prefix.  You can specify multiple interface / sla_id / prefix_len
	     per ia_pd, space separated.  IPv6RS should be disabled globally
	     when requesting a Prefix Delegation like so:

		   # Don't touch eth3 at all
		   denyinterfaces eth3

		   interface eth0
		   ia_pd 1 eth1/0 eth2/1

		   # Disable automatic address configuration for eth1
		   # eth1 still gets a delegated prefix
		   interface eth1

	     Only configure IPv4.

	     Only confgiure IPv6.

     fqdn [disable | ptr | both]
	     ptr just asks the DHCP server to update the PTR record of the
	     host in DNS whereas both also updates the A record.  disable will
	     disable the FQDN option.  The default is both.  dhcpcd itself
	     never does any DNS updates.  dhcpcd encodes the FQDN hostname as
	     specified in RFC1035.

     interface interface
	     Subsequent options are only parsed for this interface.

	     By default, when dhcpcd receives an IPv6 RA, dhcpcd will only
	     fork to the background if the RA contains at least one unexpired
	     RDNSS option.  Set this option so to make dhcpcd always fork on
	     an RA.

	     Disables kernel IPv6 Router Advertisment processing so dhcpcd can
	     manage addresses and routes.  This does not work reliably on any
	     BSD system, probably due to kernel issues.

	     Each time dhcpcd receives an IPv6 Router Adveristment, dhcpcd
	     will manage the default route only.  This allows dhcpcd to prefer
	     an interface for outbound traffic based on metric and/or user
	     selection rather than the kernel.	This does work reliably on BSD

     ipv6rs  Enables IPv6 Router Advertisment 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.

     leasetime seconds
	     Request a leasetime of seconds.

     metric metric
	     Metrics are used to prefer an interface over another one, lowest
	     wins.  dhcpcd will supply a default metric of 200 +
	     if_nametoindex(3).	 An extra 100 will be added for wireless

	     IPv4 addresses added will overwrite a pre-existing address
	     instead of working alongside.

     noarp   Don't send any ARP requests.  This also disables IPv4LL.

	     Don't require authentication even though we requested it.

     nodev   Don't load /dev management modules.

     nodhcp  Don't start DHCP or listen to DHCP messages.  This is only useful
	     when allowing IPv4LL.

	     Don't start DHCPv6 or listen to DHCPv6 messages.  Normally DHCPv6
	     is started by a RA instruction or configuration.

	     Don't install any default routes.

     nohook script
	     Don't run this hook script.  Matches full name, or prefixed with
	     2 numbers optionally ending with .sh.

	     So to stop dhcpcd from touching your DNS or MTU settings you
	     would do:-
		   nohook resolv.conf, mtu

     noipv4  Don't attempt to configure an IPv4 address.

	     Don't attempt to obtain an IPv4LL address if we failed to get one
	     via DHCP.	See RFC 3927.

     noipv6  Don't attmept to configure an IPv6 address.

	     Disable solicitation and receipt of IPv6 Router Advertisements.

     nolink  Don't receive link messages about carrier status.	You should
	     only set this for buggy interface drivers.

     option option
	     Requests the option from the server.  It can be a variable to be
	     used in dhcpcd-run-hooks(8) or the numerical value.  You can
	     specify more options separated by commas, spaces or more option
	     lines.  Prepend dhcp6_ to option to request a DHCPv6 option.
	     DHCPv4 options are mapped to DHCPv6 where applicable.

     nooption option
	     Remove the option from the DHCP message.  This should only be
	     used when a DHCP server sends a non requested option that should
	     not be processed.

     destination option
	     If dhcpcd.conf 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.

     profile name
	     Subsequent options are only parsed for this profile name.

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

     reboot seconds
	     Allow reboot seconds before moving to the DISCOVER phase if we
	     have an old lease to use.	The default is 5 seconds.  A setting
	     of 0 seconds causes 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 autho‐
	     rative which means dhcpcd will timeout before moving back to the
	     DISCOVER phase.

	     dhcpcd will release the lease prior to stopping the interface.

     require option
	     Requires the option to be present in all DHCP messages, otherwise
	     the message is ignored.  It can be a variable to be used in
	     dhcpcd-run-hooks(8) or the numerical value.  You can specify more
	     options separated by commas, spaces or more require lines.	 To
	     enforce that dhcpcd only responds to DHCP servers and not BOOTP
	     servers, you can require dhcp_message_type.

     script script
	     Use script instead of the default

     ssid ssid
	     Subsequent options are only parsed for this wireless ssid.

     static value
	     Configures a static value.	 If you set ip_address then dhcpcd
	     will not attempt to obtain a lease and just use the value for the
	     address with an infinite lease time.

	     Here is an example which configures a static address, routes and
		   interface eth0
		   static ip_address=
		   static routers=
		   static domain_name_servers=

	     Here is an example for PPP which gives the destination a default
	     route.  It uses the special destination keyword to insert the
	     destination address into the value.
		   interface ppp0
		   static ip_address=
		   destination routers

     timeout seconds
	     Timeout after seconds, instead of the default 30.	A setting of 0
	     seconds causes dhcpcd to wait forever to get a lease.  If dhcpcd
	     is working on a single interface then dhcpcd will exit when a
	     timeout occurs, otherwise dhcpcd will fork into the background.
	     If using IPv4LL then dhcpcd start the IPv4LL process after the
	     timeout and then wait a little longer before really timing out.

     userclass string
	     Tag the DHCPv4 messages with the userclass.  You can specify more
	     than one.

     vendor code,value
	     Add an encapsulated vendor option.	 code should be between 1 and
	     254 inclusive.  To add a raw vendor string, omit code but keep
	     the comma.	 Examples.

	     Set the vendor option 01 with an IP address.
		   vendor 01,
	     Set the vendor option 02 with a hex code.
		   vendor 02,01:02:03:04:05
	     Set the vendor option 03 with an IP address as a string.
		   vendor 03,\"\"
	     Set un-encapsulated vendor option to hello world.
		   vendor ,"hello world"

     vendorclassid string
	     Set the DHCP Vendor Class.	 DHCPv6 has it's own option as shown
	     below.  The default is dhcpcd-<version>:<os>:<machine>:<plat‐
	     form>.  For example
	     If not set then none is sent.  Some badly configured DHCP servers
	     reject unknown vendorclassids.  To work around it, try and imper‐
	     sonate Windows by using the MSFT vendorclassid.

     vendclass en data
	     Add the DHCPv6 Vendor Indetifying Vendor Class with the IANA
	     assigned Enterprise Number en with the 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.

     waitip [4 | 6]
	     Wait for an address to be assigned before forking to the back‐
	     ground.  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, dhcpcd.conf will wait for any address protocol to be
	     assigned.	It is possible to wait for more than one address pro‐
	     tocol and dhcpcd.conf will only fork to the background when all
	     waiting conditions are satisfied.

	     Use the last four bytes of the hardware address as the DHCP xid
	     instead of a randomly generated number.

   Defining new options
     DHCP allows for the use of custom options.	 Each option needs to be
     started with the define or define6 directive.  This can optionally be
     followed by both embed or encap options.  Both can be specified more than
     once and embed must come before encap.

     define code type variable
	     Defines the DHCP option code of type with a name of variable
	     exported to dhcpcd-run-hooks(8).

     define6 code type variable
	     Defines the DHCPv6 option code of type with a name of variable
	     exported to dhcpcd-run-hooks(8), with a prefix of _dhcp6.

     vendopt code type variable
	     Defines the Vendor-Identifying Vendor Options.  The code is the
	     IANA Enterprise Number which will unqiuely describe the encapsu‐
	     lated options.  type is normally encap.  variable names the Ven‐
	     dor option to be exported.

     embed type variable
	     Defines an embedded variable within the defined option.  The
	     length is determined by the type.	If the variable is not the
	     same as defined in the parent option, it is prefixed with the
	     parent variable first with an underscore.

     encap code type variable
	     Defines an encapsulated variable within the defined option.  The
	     length is determined by the type.	If the variable is not the
	     same as defined in the parent option, it is prefixed with the
	     parent variable first with an underscore.

   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

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

	      This option cannot be requested, regardless of user configura‐

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

     array    The option data is split into a space seperated array, each ele‐
	      ment being the same type.

   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.

	     An IPv4 address, 4 bytes

	     An IPv6 address, 16 bytes

     string [: length]
	     A shell escaped string (binary data escaped as octal)

     byte    A byte

     int16   A signed 16bit integer, 2 bytes

     uint16  An unsigned 16bit integer, 2 bytes

     int32   A signed 32bit integer, 4 bytes

     uint32  An unsigned 32bit integer, 4 bytes

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

     domain  A RFC 3397 encoded string

     binhex [: length]
	     Binary data expressed as hexadecimal

     embed   Contains embedded options (implies encap as well)

     encap   Contains encapsulated options (implies embed as well)

     option  References an option from the global definition

   Example definition
	   # DHCP option 81, Fully Qualified Domain Name, RFC4702
	   define 81 embed fqdn
	   embed byte flags
	   embed byte rcode1
	   embed byte rcode2
	   embed domain fqdn

	   # DHCP option 125, Vendor Specific Information Option, RFC3925
	   define 125 encap vsio
	   embed uint32 enterprise_number
	   # Options defined for the enterprise number
	   encap 1 ipaddress ipaddress

   Supported protocols
     token    Sends and expects the token with the secretid 0 in each message.

	      Delayed Authentication.  dhcpcd will send an authentication
	      option with no key or MAC.  The server will see this option, and
	      select a key for dhcpcd.conf, writing the realm and secretid in
	      it.  dhcpcd will then look for a non-expired token with a match‐
	      ing realm and secretid.  This token is used to authenicate all
	      other messages.

     delayed  Same as above, but without a realm.

   Supported algorithms
     If none specified, hmac-md5 is the default.


   Supported Replay Detection Mechanisms
     If none specified, 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
     clients Replay Detection Value reset.

	      Read the number in the file /var/lib/dhcpcd/dhcpcd-rdm.monotonic
	      and add one to it.

	      Create a NTP timestamp from the system time.

	      Same as monotime.

     fnmatch(3), if_nametoindex(3), dhcpcd(8), dhcpcd-run-hooks(8)

     Roy Marples ⟨roy@marples.name⟩

     When configuring DHCPv6 you can only select one IA type.  I can't think
     of a use case where you would want different types, so if you have one
     then please bring it up for discussion on the
     ⟨dhcpcd-discuss@marples.name⟩ mailing list.

     Please report them to

BSD			       January 30, 2014				   BSD

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