Provided by: dhcpcd5_7.1.0-2build1_amd64 bug


     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.  Comments can be prefixed with the #
     character.  String values should be quoted with the " character.

     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

                   # My specific network
                   profile dd:ee:aa:dd:bb:ee
                   static ip_address=

                   # A generic network
                   static ip_address=

     authprotocol protocol [algorithm [rdm]]
             Authenticate DHCP messages.  See the Supported Authentication Protocols section.  If
             protocol is token then algorithm is snd_secretid/rcv_secretid so you can send and
             receive different tokens.

     authtoken secretid realm expire key
             Define a shared key for use in authentication.  realm can be "" to for use with the
             delayed protocol.  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.  For the token protocol, secretid needs to be 0 and realm needs to be "".
             If dhcpcd has the error
                   dhcp_auth_encode: Invalid argument
             then it means that dhcpcd could not find the correct authentication token in your

             Fork to the 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.

     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.

             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.

     controlgroup group
             Sets the group ownership of /run/dhcpcd.sock so that users other than root can
             connect to dhcpcd.

     debug   Echo debug messages to the stderr and syslog.

     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.  Or
             set which driver wpa_supplicant(8) should use with env wpa_supplicant_driver=nl80211

             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, 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    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 clientid.  The DUID generated
             will be held in /var/lib/dhcpcd/duid and should not be copied to other hosts.  This
             file also takes precedence over the above rules.

     iaid iaid
             Set the Interface Association Identifier to iaid.  This option must be used in an
             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 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.

     dhcp    Enable DHCP on the interface, on by default.

     dhcp6   Enable DHCPv6 on the interface, on by default.

     ipv4    Enable IPv4 on the interface, on by default.

     ipv6    Enable IPv6 on the interface, on by default.

     request [address]
             Request the address in the DHCP DISCOVER message.  There is no guarantee this is the
             address the DHCP server will actually give.  If no address is given then the first
             address currently assigned to the interface is used.

     inform [address[/cidr[/broadcast_address]]]
             Behaves like 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 address in
             use.  You should also include the optional cidr network number in case the address
             is not already configured on the interface.  dhcpcd remains running and pretends it
             has an infinite lease.  dhcpcd will not de-configure the interface when it exits.
             If dhcpcd fails to contact a DHCP server then it returns a failure instead of
             falling back on IPv4LL.

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

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

     hostname name
             Sends the hostname name to the DHCP server so it can be registered in DNS.  If name
             is an empty string then the current system hostname is sent.  If name is a FQDN
             (i.e., 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 [/ address]]
             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 [/ prefix / prefix_len] [interface [/ sla_id [/ prefix_len [/ suffix]]]]]
             Request a DHCPv6 Delegated Prefix for iaid.  This option must be used in an
             interface block.  Unless a 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 interface is given then
             we will assign a prefix to every other interface with a sla_id equivalent to the
             interface index assigned by the OS.  Otherwise addresses are only assigned for each
             interface and sla_id.  Each assigned address will have a suffix, defaulting to 1.
             If the suffix is 0 then a SLAAC address is assigned.  You cannot assign a prefix to
             the requesting interface unless the DHCPv6 server supports the RFC 6603 Prefix
             Exclude Option.  dhcpcd has to be running for all the interfaces it is delegating
             to.  A default prefix_len of 64 is assumed, unless the maximum sla_id does not fit.
             In this case prefix_len is increased to the highest multiple of 8 that can
             accommodate the sla_id.  sla_id is an integer which must be unique inside the iaid
             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

             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.  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.

             noipv6rs                 # disable routing solicitation
             denyinterfaces eth2      # Don't touch eth2 at all
             interface eth0
               ipv6rs                 # enable routing solicitation get the
                                      # default IPv6 route
               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

             Only configure IPv4.

             Only configure IPv6.

     fqdn [disable | none | ptr | both]
             none will not ask the DHCP server to update DNS.  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 RFC 1035.

     interface interface
             Subsequent options are only parsed for this interface.

             Generate SLAAC addresses for each Prefix advertised by an IPv6 Router Advertisement
             message with the Auto flag set.  On by default.

             Disables the above option.

             By default, when dhcpcd receives an IPv6 Router Advertisement, 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 dhcpcd always fork on
             an RA.

     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.

     leasetime seconds
             Request a leasetime of seconds.

     logfile logfile
             Writes to the specified logfile rather than syslog(3).  The logfile is reopened when
             dhcpcd receives the SIGUSR2 signal.

     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 interfaces.

     mudurl 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.

             Any pre-existing IPv4 addresses will be removed from the interface when adding a new
             IPv4 address.

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

             Don't require authentication even though we requested it.  Also allows FORCERENEW
             and RECONFIGURE messages without authentication.

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

     nodev   Don't load /dev management modules.

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

             Don't start DHCPv6 or listen to DHCPv6 messages.  Normally DHCPv6 is started by an
             IPv6 Router Advertisement instruction or configuration.

             Don't install any default routes.

             Install a default route if available (default).

     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 settings or starting wpa_supplicant you
             would do:-
                   nohook resolv.conf, wpa_supplicant

     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

     noipv6  Don't solicit or accept IPv6 Router Advertisements and DHCPv6.

             Don't solicit or accept IPv6 Router Advertisements.

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

     noup    Don't bring the interface up when in master mode.  If dhcpcd.conf cannot determine
             the carrier state, dhcpcd.conf will enter a tight polling loop until the interface
             is marked up and running or a valid carrier state is reported.

     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.  If no DHCPv6 options are configured, then DHCPv4 options are mapped
             to equivalent DHCPv6 options.

             Prepend nd_ to option to handle ND options, but this only works for the nooption,
             reject and require options.

             To see a list of options you can use, call dhcpcd with the -V, --variables argument.

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

     require option
             Requires the option to be present in all messages, otherwise the message is ignored.
             To enforce that dhcpcd only responds to DHCP servers and not BOOTP servers, you can
             require dhcp_message_type.  This isn't an exact science though because a BOOTP
             server can send DHCP-like options.

     reject option
             Reject a message that contains the option.  This is useful when you cannot use
             require to select / de-select BOOTP messages.

     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

     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 and moving from DISCOVER to IPv4LL if no reply.  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 authoritative
             which means dhcpcd will timeout before moving back to the DISCOVER phase.

             dhcpcd will release the lease prior to stopping the interface.

     script script
             Use script instead of the default /lib/dhcpcd/dhcpcd-run-hooks.

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

     slaac [hwaddr | private]
             Selects the interface identifier used for SLAAC generated IPv6 addresses.  If
             private is used, an RFC 7217 address is generated.

     static value
             Configures a static value.  If you set ip_address then 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 ip6_address, dhcpcd will continue auto-configuation as normal.

             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 inform6 command here if you wished to obtain more information via
             DHCPv6.  For IPv4, you should use the inform ipaddress option instead of setting a
             static address.
                   interface eth0
                   static ip_address=
                   static broadcast_address=
                   static ip6_address=fd51:42f8:caae:d92e::ff/64
                   static routers=
                   static domain_name_servers= fd51:42f8:caae:d92e::1

             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
             Time out 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 its own option as shown below.  The default
             is dhcpcd-<version>:<os>:<machine>:<platform>.  For example
             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

     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 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, dhcpcd.conf will wait for any address protocol
             to be assigned.  It is possible to wait for more than one address protocol and
             dhcpcd.conf will only fork to the background when all waiting conditions are

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

   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 define, definend,
     define6 or vendopt 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

     definend code type variable
             Defines the ND option code of type with a name of variable exported to
             dhcpcd-run-hooks(8), with a prefix of _nd.

     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 uniquely describe the encapsulated options.  type is normally
             encap.  variable names the Vendor 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.  If the variable has the
             name of reserved then it is not processed.

     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 below.

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

              This option cannot be requested, regardless of user configuration.

              This option is optional.  Only makes sense for embedded options like the client
              FQDN option, where the FQDN string itself is optional.

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

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

   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 NVT ASCII string of printable characters.

     byte    A byte.

     bitflags: 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.

     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  An RFC 3397 encoded string.

     dname   An RFC 1035 validated 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, RFC 4702
           define 81 embed fqdn
           embed byte flags
           embed byte rcode1
           embed byte rcode2
           embed domain fqdn

           # DHCP option 125, Vendor Specific Information Option, RFC 3925
           define 125 encap vsio
           embed uint32 enterprise_number
           # Options defined for the enterprise number
           encap 1 ipaddress ipaddress

   Supported Authentication Protocols
     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 secretid
              of 0 will be used in sending messages and validating received messages.

              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 an unexpired token with a
              matching realm and secretid.  This token is used to authenticate all other

     delayed  Same as above, but without a realm.

   Supported Authentication 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 client's Replay Detection Value reset.

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

              Create an NTP timestamp from the system time.

              Same as monotime.


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


     Roy Marples <>


     Please report them to