Updated: 2021/Dec/3

DHCPCD.CONF(5)                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.  Comments can be prefixed
     with the # character.  String values should be quoted with the "

     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).

             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 after the anonymous option is
             processed.  As such, the anonymous option should be the last
             option in the configuration unless you really want to send
             something which could identify you.  dhcpcd will not try and
             reboot an old lease, it will go straight into DISCOVER/SOLICIT.

             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.

     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

     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 configuration.

             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 /var/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

             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 [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 /var/db/dhcpcd/duid does not exist.  If not ll, lt or
             uuid then value will be converted from 00:11:22:33 format.  This,
             plus the IAID will be used as the clientid.  The DUID generated
             will be held in /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.

     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 [/
             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 Delegation.

             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 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

             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

             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 a

     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 lease time of seconds.  -1 represents an infinite lease
             time.  By default dhcpcd does not request any lease time and
             leaves it in the hands of the DHCP server.

     link_rcvbuf size
             Override the size of the link receive buffer from the kernel
             default.  While dhcpcd will recover from link buffer overflows,
             this may not be desirable on heavily loaded systems.

     logfile logfile
             Writes to the specified logfile.  dhcpcd still writes to
             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 1000 +
             if_nametoindex(3).  This will be offset by 2000 for wireless
             interfaces, with additional offsets of 1000000 for IPv4LL and
             2000000 for roaming 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

             Don't delay for an initial randomised time when starting

     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 an IPv6 Router Advertisement instruction or

             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 3927.

     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 manager mode.

     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 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.  Allow reboot seconds before starting
             fallback states from the DISCOVER phase.  IPv4LL is started when
             the first reboot timeout is reached.  The default is 5 seconds.
             A setting of 0 seconds causes dhcpcd.conf 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.  This has no effect on DHCPv6 other
             than skipping the reboot phase.

             dhcpcd will release the lease prior to stopping the interface.

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

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

     slaac hwaddr | private [temp | temporary]
             Selects the interface identifier used for SLAAC generated IPv6
             addresses.  If private is used, a RFC 7217 address is generated.
             The temporary directive will create a temporary address for the
             prefix as well.

     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-configuration 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=

             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 message with the userclass.  You can specify more
             than one.

     msuserclass string
             Tag the DHCPv4 mesasge with the Microsoft userclass.  Unlike the
             userclass option, this one can only be added once.  It should
             only be used for Microsoft DHCP servers and the vendorclassid
             should be set to "MSFT 98" or "MSFT 5.0".  This option is not RFC

     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 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
             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 satisfied.

             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 dhcpcd-run-hooks(8).

     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

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

              This option cannot be requested, regardless of user

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

     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 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 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

     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 messages.

     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/db/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 <roy@marples.name>

     Please report them to http://roy.marples.name/projects/dhcpcd

NetBSD 9.99                     August 23, 2021                    NetBSD 9.99