DHCPCD.CONF(5) File Formats Manual DHCPCD.CONF(5) dhcpcd.conf - dhcpcd (DESCRIPTION) dhcpcd . dhcpcd(8) . . (trim) . . # . " () . : allowinterfaces pattern pattern fnmatch(3) . denyinterfaces . denyinterfaces pattern pattern fnmatch(3) . anonymous (Anonymity Profiles) DHCP RFC 7844 . DUID ClientID LL . dhcpcd allow . allow request . anonymous . dhcpcd (reboot lease) DISCOVER/SOLICIT . randomise_hwaddr (carrier) . anonymous . arping address [address] DHCP dhcpcd arping . (profile) IP . : interface bge0 arping 192.168.0.1 # My specific 192.168.0.1 network profile dd:ee:aa:dd:bb:ee static ip_address=192.168.0.10/24 # A generic 192.168.0.1 network profile 192.168.0.1 static ip_address=192.168.0.98/24 authprotocol protocol [algorithm [rdm]] DHCP . . protocol token algorithm snd_secretid/rcv_secretid . authtoken secretid realm expire key . realm delayed "" . expire "yyy- mm-dd HH:MM" . forever 0 . token secretid 0 realm "" . dhcpcd dhcp_auth_encode: Invalid argument dhcpcd . background () . (link) (carrier) . blacklist address[/cidr] address[/cidr] . whitelist address[/cidr] address[/cidr] . whitelist blacklist . bootp BOOTP . DHCP Message Type BOOTP . DHCP . broadcast DHCP ( ) . FireWire InfiniBand . dhcpcd . controlgroup group dhcpcd ( ) . readgroup group dhcpcd . debug stderr syslog . dev value /dev value . dhcpcd ( ) . env value value dhcpcd-run-hooks(8) . env force_hostname=YES hostname . wpa_supplicant(8) : env wpa_supplicant_driver=nl80211 . RFC 4702 FQDN . FQDN dhcpcd FQDN hostname domain . env hostname_fqdn=[YES|NO|SERVER] . SERVER . DHCPv4 DHCPv6 DHCPv4 DHCPv6 FQDN . DHCPv6 (hostname) . clientid string clientid . 01:02:03 . clientid dhcpcd clientid . duid [ll | lt | uuid | value] DHCP DUID (DHCP Unique Identifier) . DUID-LLT ( + ) DUID-LL ( ) . /var/lib/dhcpcd/duid DUID . ll, lt uuid value 00:11:22:33 . IAID clientid . DUID /var/lib/dhcpcd/duid . . iaid iaid (Interface Association Identifier) iaid . interface . VLANID ( 0xff) . dhcpcd . IAID . dhcp DHCP . dhcp6 DHCPv6 . ipv4 IPv4 . ipv6 IPv6 . request [address] address DHCP DISCOVER . DHCP . address interface . inform [address[/cidr[/broadcast_address]]] request DISCOVER/REQUEST DHCP INFORM . DHCP address . cidr . dhcpcd . dhcpcd . dhcpcd DHCP IPv4LL . inform6 DHCPv6 Information Request . DHCPv6 . (IPv6 Router Advertisement) . dhcpcd IPv6 RA DHCPv6 Information Request . persistent dhcpcd . NFS SSH . . fallback profile DHCP (profile) . ZeroConf . initial_interval seconds DHCPv4 seconds . . RFC 2131 . DHCPv4 DHCPv6 RFC 8415 . backoff_cutoff backoff_jitter . backoff_cutoff seconds (exponential backoff) DHCPv4 seconds . . RFC 2131 . seconds initial_interval (cutoff) . initial_interval backoff_cutoff (jitter) . DHCPv4 DHCPv6 RFC 8415 . initial_interval backoff_jitter . backoff_jitter milliseconds (jitter) DHCPv4 . +- milliseconds . RFC 2131 (+- ) . () . DHCPv4 DHCPv6 RFC 8415 . backoff_cutoff initial_interval . fallback_time seconds (fallback) seconds . . hostname name name DHCP DNS . name . name FQDN ( . ) . hostname_short FQDN DHCP . DHCP FQDN DNS . env . ia_na [iaid [/ address]] DHCPv6 (Normal Address) iaid . iaid iaid . iaid ia_na . ia_ta [iaid] DHCPv6 (Temporary Address) iaid . iaid ia_ta . ia_pd [iaid [/ prefix / prefix_len] [interface [/ sla_id [/ prefix_len [/ suffix]]]]] (Delegated Prefix) DHCPv6 iaid . interface . sla_id (reject route) . interface sla_id . interface sla_id . - . suffix . suffix SLAAC . DHCPv6 RFC 6603 ( Prefix Exclude Option) . dhcpcd . prefix_len sla_id . prefix_len sla_id . sla_id iaid prefix_len . interface / sla_id / prefix_len ia_pd . Prefix Delegation IPv6RS . eth0 IPv4 IPv6 . DHCPv4 IPv4 . DHCPv6 IPv6 /64 . eth1 (::1) IPv6 . . rtadvd(8) eth1 eth2 eth3 IPv6 . noipv6rs # denyinterfaces eth2 # eth2 interface eth0 ipv6rs # eth0 ia_na 1 # IPv6 ia_pd 2 eth1/0 # PD eth1 ia_pd 3 eth2/1 eth3/2 # PD eth2 eth3 ia_pd 4 - # PD ipv4only IPv4 . ipv6only IPv6 . fqdn [disable | none | ptr | both] none DHCP DNS . ptr DHCP PTR DNS both A . disable FQDN . both . dhcpcd DNS . dhcpcd FQDN RFC 1035 . interface interface interface . fnmatch(3) . ipv4ll_time seconds IPv4LL seconds . . ipv6ra_autoconf (IPv6 Router Advertisement) Auto SLAAC . . ipv6ra_noautoconf . ipv6ra_fork dhcpcd IPv6 RA RDNSS DHCPv6 . dhcpcd RA . ipv6rs (IPv6 Router Advertisement solicitation) . . lastlease dhcpcd . lastleaseextend . ARP dhcpcd . . RFC 2131 . leasetime seconds DHCP seconds . -1 . dhcpcd DHCP . DHCPv6 RFC . . . . . RFC 8415 . link_rcvbuf size (link receive buffer) . dhcpcd . logfile logfile logfile . dhcpcd syslog(3) . dhcpcd SIGUSR2 logfile . metric metric . dhcpcd 1000 + if_nametoindex(3) . IPv4LL () . mudurl url (URL) (MUD) . . draft-ietf-opsawg-mud . noalias IPv4 IPv4 . noarp ARP . IPv4LL . arp_persistdefence IP IP . noauthrequired . FORCERENEW RECONFIGURE . nodelay . nodev /dev . nodhcp DHCP DHCP . IPv4LL . nodhcp6 DHCPv6 DHCPv6 . DHCPv6 IPv6 . nogateway . gateway (). nohook script . .sh . DNS wpa_supplicant dhcpcd : nohook resolv.conf, wpa_supplicant noipv4 IPv4 . noipv4ll DHCP IPv4LL . : RFC 3927. noipv6 IPv6 DHCPv6 . noipv6rs IPv6 . nolink (carrier) . . nosyslog syslog(3) . noup (up) . option option option . dhcpcd-run-hooks(8) . option option . DHCPv6 dhcp6_ option . DHCPv6 DHCPv4 DHCPv6 . ND nd_ option . dhcpcd -V, --variables . allow option nooption . allow nooption . option . nooption option . require option option . dhcpcd DHCP BOOTP dhcp_message_type require . BOOTP DHCP . reject option option . require BOOTP . destination option dhcpcd ( PPP TUN ) DHCP . profile name name . quiet dhcpcd . reboot seconds reboot DISCOVER . reboot (fallback) DISCOVER . IPv4LL reboot . . dhcpcd (reboot) DISCOVER . A B A B DHCP (authoritative) dhcpcd DISCOVER . DHCPv6 . release dhcpcd . script script /usr/lib/dhcpcd/dhcpcd-run-hooks script . request_time seconds DISCOVER seconds . . ssid ssid ssid . slaac hwaddr | private | token token [temp | temporary] IPv6 SLAAC . private RFC 7217 . token token . temporary . static value value . ip_address dhcpcd . . (profiles) ip_address . 0.0.0.0 (3rdparty) . ip6_address dhcpcd . IPv4 IPv4 DNS IPv6 . DHCPv6 inform6 . IPv4 inform ipaddress . interface eth0 noipv6rs static ip_address=192.168.0.10/24 static broadcast_address=192.168.0.63 static ip6_address=fd51:42f8:caae:d92e::ff/64 static routers=192.168.0.1 static domain_name_servers=192.168.0.1 fd51:42f8:caae:d92e::1 PPP . destination . interface ppp0 static ip_address=0.0.0.0 destination routers timeout seconds seconds (timeout) . seconds dhcpcd . dhcpcd dhcpcd . IPv4LL dhcpcd IPv4LL . userclass string DHCPv4 (userclass) . . msuserclass string DHCPv4 . userclass, . DHCP vendorclassid "MSFT 98" "MSFT 5.0" . RFC . vendor code,value (DHCP Option 43) . code ( ) . code . : 01 IP: vendor 01,192.168.0.2 02 : vendor 02,01:02:03:04:05 03 IP : vendor 03,\"192.168.0.2\" hello world: vendor ,"hello world" vsio en code,value (DHCP Option 125) IANA en code ( ) value . : vsio 01 IPv4: vsio 155 01,192.168.1.1 vsio 02 : vsio 155 02,"hello world" vsio 01 : vsio 255 01,01:02:03:04:05 vsio6 en code,value (DHCPv6 Option 17) IANA en code ( ) value . : vsio 01 IPv6: vsio6 155 01,2001:0db8:85a3:0000:0000:8a2e:0370:7334 vsio 02 : vsio6 155 02,"hello world" vsio 01 : vsio6 255 01,01:02:03:04:05 vendorclassid string DHCP (DHCP Vendor Class) . DHCPv6 . dhcpcd-::: . : dhcpcd-5.5.6:NetBSD-6.99.5:i386:i386 . DHCP vendorclassid . vendorclassid MSFT . vendclass en data DHCPv6 IANA en data . RFC 3925 . waitip [4 | 6] . IPv4 . IPv6 . dhcpcd . dhcpcd . xidhwaddr DHCP xid . (Defining new options) DHCP ND DHCPv6 RFC 3925 DHCP . define, definend, define6 vendopt . embed encap . embed encap . define code type variable DHCP code type variable dhcpcd-run-hooks(8) . definend code type variable ND code type variable nd_ dhcpcd-run-hooks(8) . define6 code type variable DHCPv6 code type variable dhcp6_ dhcpcd-run-hooks(8) . vendopt code type variable (Vendor-Identifying Vendor Options) . code IANA . type encap . variable . embed type variable (embedded) . type . variable variable (underscore) . variable reserved . encap code type variable (encapsulated) . type . variable variable . (Type prefix) . . request . norequest . optional . FQDN FQDN . index . array . truncated (truncated) . (zero-padded) . ip6address . (Types to define) . . string binhex . ipaddress IPv4 . ip6address IPv6 . string [: length] NVT ASCII . byte . bitflags: flags (most significant bit). ABCDEFGH A 10000000 B 01000000 C 00100000 . . 0 . . 1 . int16 . uint16 . int32 . uint32 . flag (1) . domain RFC 3397. dname RFC 1035. uri URI . URI . URI URI . binhex [: length] . embed ( encap ). encap ( embed ). option . (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 . . secretid . delayedrealm (Delayed Authentication). dhcpcd MAC . dhcpcd realm secretid . dhcpcd realm secretid . . delayed (realm). (Supported Authentication Algorithms) hmac-md5 . hmac-md5 (Supported Replay Detection Mechanisms) monotonic . DHCP (Replay Detection Value) . monocounter /var/lib/dhcpcd/dhcpcd-rdm.monotonic . monotime NTP . monotonic monotime . (SEE ALSO) fnmatch(3), if_nametoindex(3), dhcpcd(8), dhcpcd-run-hooks(8) (AUTHORS) Roy Marples (BUGS) https://roy.marples.name/projects/dhcpcd . Linux 6.12.107+deb13-amd64 July 29, 2026 Linux 6.12.107+deb13-amd64