DHCPCD.CONF(5)            NetBSD 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 Authentication
             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.
             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 authentica-
             tion token in your configuration.

             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.

     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, 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.

     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.

             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 [/ 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 [/
             Request a DHCPv6 Delegated Prefix for iaid.  This option must be
             used in an interface block.  Unless a sla_id of 0 is assigned, a
             reject route is installed for the Delegated Prefix to stop unal-
             located 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 of 1.  You can-
             not assign a prefix to the requesting interface unless the DHCPv6
             server supports RFC6603 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 multi-
             ple of 8 that can accommodate the sla_id.  sla_id is an integer
             and is added to the prefix which must fit inside prefix_len less
             the length of the delegated prefix.  sla_id can be 0 only if the
             Delegated Prefix is assigned to one interface. You can specify
             multiple interface / sla_id / prefix_len per ia_pd, space sepa-
             rated.  IPv6RS should be disabled globally when requesting a Pre-
             fix 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.
             rtadvd(8) can be used with an empty configuration file on eth1 to
             provide automatic IPv6 address configuration for the internal

             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  # get a /64 and assign it to eth1

             To be RFC compliant, dhcpcd cannot mix Prefix Delegation with
             other DHCPv6 address types in the same session.  This has a num-
             ber of issues: additional DHCP traffic and potential collisions
             between options.  ia_pd_mix enables
             draft-ietf-dhc-dhcpv6-stateful-issues-06 support so that Prefix
             Delegation can be mixed with other address types in the same ses-

             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.

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

             Disables the above option.

             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 and a valid prefix or no DHCPv6 instruction.  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.

             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.

     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

             Any pre-existing IPv4 addresses existing address 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.

     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.

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

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

     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]
             Selects the interface identifier used for SLAAC generated IPv6
             addresses.  If private is used, a RFC7217 address is generated.

     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 separated 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 NVT ASCII string of printable characters.

     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

     dname   A 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, 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 Authentication Protocols
     token    Sends and expects the token with the secretid 0 and realm of ""
              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 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
     clients Replay Detection Value reset.

              Read the number in the file /var/db/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>

     Please report them to

NetBSD 7.1.2                   January 20, 2015                   NetBSD 7.1.2

You can also request any man page by name and (optionally) by section:


Use the DEFAULT collection to view manual pages for third-party software.

©1994 Man-cgi 1.15, Panagiotis Christias
©1996-2019 Modified for NetBSD by Kimmo Suominen