{ "mode": "man", "parameter": "DHCPCD.CONF", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/DHCPCD.CONF/5/json", "generated": "2026-10-04T06:53:30Z", "sections": { "NAME": { "content": "dhcpcd.conf — dhcpcd configuration file\n", "subsections": [] }, "DESCRIPTION": { "content": "Although dhcpcd can do everything from the command line, there are cases where it's just eas‐\nier to do it once in a configuration file. Most of the options found in dhcpcd(8) can be\nused here. The first word on the line is the option and the rest of the line is the value.\nLeading and trailing whitespace for the option and value are trimmed. You can escape charac‐\nters in the value using the \\ character. Comments can be prefixed with the # character.\nString values should be quoted with the \" character.\n\nHere's a list of available options:\n\nallowinterfaces pattern\nWhen discovering interfaces, the interface name must match pattern which is a space\nor comma separated list of patterns passed to fnmatch(3). If the same interface is\nmatched in denyinterfaces then it is still denied.\n\ndenyinterfaces pattern\nWhen discovering interfaces, the interface name must not match pattern which is a\nspace or comma separated list of patterns passed to fnmatch(3).\n", "subsections": [ { "name": "anonymous", "content": "Enables Anonymity Profiles for DHCP, RFC 7844. Any DUID is ignored and ClientID is\nset to LL only. All non essential options are then masked at this point, but they\ncould be unmasked by explicitly requesting the option after the anonymous option is\nprocessed. As such, the anonymous option should be the last option in the configura‐\ntion unless you really want to send something which could identify you. dhcpcd will\nnot try and reboot an old lease, it will go straight into DISCOVER/SOLICIT.\n" }, { "name": "randomise_hwaddr", "content": "Forces a hardware address randomisation when the interface is brought up or when the\ncarrier is lost. This is generally used in tandem with the anonymous option.\n\narping address [address]\ndhcpcd will arping each address in order before attempting DHCP. If an address is\nfound, we will select the replying hardware address as the profile, otherwise the IP\naddress. Example:\n\ninterface bge0\narping 192.168.0.1\n\n# My specific 192.168.0.1 network\nprofile dd:ee:aa:dd:bb:ee\nstatic ipaddress=192.168.0.10/24\n\n# A generic 192.168.0.1 network\nprofile 192.168.0.1\nstatic ipaddress=192.168.0.98/24\n\nauthprotocol protocol [algorithm [rdm]]\nAuthenticate DHCP messages. See the Supported Authentication Protocols section. If\nprotocol is token then algorithm is sndsecretid/rcvsecretid so you can send and re‐\nceive different tokens.\n\nauthtoken secretid realm expire key\nDefine a shared key for use in authentication. realm can be \"\" to for use with the\ndelayed protocol. expire is the date the token expires and should be formatted \"yyy-\nmm-dd HH:MM\". You can use the keyword forever or 0 which means the token never ex‐\npires. For the token protocol, secretid needs to be 0 and realm needs to be \"\". If\ndhcpcd has the error\ndhcpauthencode: Invalid argument\nthen it means that dhcpcd could not find the correct authentication token in your\nconfiguration.\n" }, { "name": "background", "content": "Fork to the background immediately. This is useful for startup scripts which don't\ndisable link messages for carrier status.\n\nblacklist address[/cidr]\nIgnores all packets from address[/cidr].\n\nwhitelist address[/cidr]\nOnly accept packets from address[/cidr]. blacklist is ignored if whitelist is set.\n\nbootp Be a BOOTP client. Basically, this just doesn't send a DHCP Message Type option and\nwill only interact with a BOOTP server. All other DHCP options still work.\n" }, { "name": "broadcast", "content": "Instructs the DHCP server to broadcast replies back to the client. Normally this is\nonly set for non-Ethernet interfaces, such as FireWire and InfiniBand. In most\ncases, dhcpcd will set this automatically.\n\ncontrolgroup group\nSets the group ownership of /run/dhcpcd/sock so that users other than root can con‐\nnect to dhcpcd.\n\ndebug Echo debug messages to the stderr and syslog.\n\ndev value\nLoad the value /dev management module. dhcpcd will load the first one found to work,\nif any.\n\nenv value\nPush value to the environment for use in dhcpcd-run-hooks(8). For example, you can\nforce the hostname hook to always set the hostname with env forcehostname=YES. Or\nset which driver wpasupplicant(8) should use with env wpasupplicantdriver=nl80211\n\nIf the hostname is set, it will be will set to the FQDN if possible as per RFC 4702,\nsection 3.1. If the FQDN option is missing, dhcpcd will still try and set a FQDN\nfrom the hostname and domain options for consistency. To override this, set env\nhostnamefqdn=[YES|NO|SERVER]. A value of SERVER means just what the server says,\ndon't manipulate it. This could lead to an inconsistent hostname on a DHCPv4 and\nDHCPv6 network where the DHCPv4 hostname is short and the DHCPv6 has an FQDN. DHCPv6\nhas no hostname option.\n\nclientid string\nSend the clientid. If the string is of the format 01:02:03 then it is encoded as\nhex. For interfaces whose hardware address is longer than 8 bytes, or if the\nclientid is an empty string then dhcpcd sends a default clientid of the hardware fam‐\nily and the hardware address.\n\nduid [ll | lt | uuid | value]\nUse a DHCP Unique Identifier. If a system UUID is available, that will be used to\ncreate a DUID-UUID, otherwise if persistent storage is available then a DUID-LLT\n(link local address + time) is generated, otherwise DUID-LL is generated (link local\naddress). The DUID type can be hinted as an optional parameter if the file\n/var/lib/dhcpcd/duid does not exist. If not ll, lt or uuid then value will be con‐\nverted from 00:11:22:33 format. This, plus the IAID will be used as the clientid.\nThe DUID generated will be held in /var/lib/dhcpcd/duid and should not be copied to\nother hosts. This file also takes precedence over the above rules except for setting\na value.\n\niaid iaid\nSet the Interface Association Identifier to iaid. This option must be used in an\ninterface block. This defaults to the VLANID (prefixed with 0xff) for the interface\nif set, otherwise the last 4 bytes of the hardware address assigned to the interface.\nEach instance of this should be unique within the scope of the client and dhcpcd\nwarns if a conflict is detected. If there is a conflict, it is only a problem if the\nconflicted IAIDs are used on the same network.\n\ndhcp Enable DHCP on the interface, on by default.\n\ndhcp6 Enable DHCPv6 on the interface, on by default.\n\nipv4 Enable IPv4 on the interface, on by default.\n\nipv6 Enable IPv6 on the interface, on by default.\n\nrequest [address]\nRequest the address in the DHCP DISCOVER message. There is no guarantee this is the\naddress the DHCP server will actually give. If no address is given then the first\naddress currently assigned to the interface is used.\n\ninform [address[/cidr[/broadcastaddress]]]\nBehaves like request as above, but sends a DHCP INFORM instead of DISCOVER/REQUEST.\nThis does not get a lease as such, just notifies the DHCP server of the address in\nuse. You should also include the optional cidr network number in case the address is\nnot already configured on the interface. dhcpcd remains running and pretends it has\nan infinite lease. dhcpcd will not de-configure the interface when it exits. If\ndhcpcd fails to contact a DHCP server then it returns a failure instead of falling\nback on IPv4LL.\n" }, { "name": "inform6", "content": "Performs a DHCPv6 Information Request. No address is requested or specified, but all\nother DHCPv6 options are allowed. This is normally performed automatically when an\nIPv6 Router Advertisement indicates that the client should perform this operation.\nThis option is only needed when dhcpcd is not processing IPv6 RA messages and the\nneed for a DHCPv6 Information Request exists.\n" }, { "name": "persistent", "content": "dhcpcd normally de-configures the interface and configuration when it exits. Some‐\ntimes, this isn't desirable if, for example, you have root mounted over NFS or SSH\nclients connect to this host and they need to be notified of the host shutting down.\nYou can use this option to stop this from happening.\n\nfallback profile\nFall back to using this profile if DHCP fails. This allows you to configure a static\nprofile instead of using ZeroConf.\n\nhostname name\nSends the hostname name to the DHCP server so it can be registered in DNS. If name\nis an empty string then the current system hostname is sent. If name is a FQDN\n(i.e., contains a .) then it will be encoded as such.\n" }, { "name": "hostname_short", "content": "Sends the short hostname to the DHCP server instead of the FQDN. This is useful be‐\ncause DHCP servers will not register the FQDN in their DNS if the domain part does\nnot match theirs.\n\nAlso, see the env option above to control how the hostname is set on the host.\n\niana [iaid [/ address]]\nRequest a DHCPv6 Normal Address for iaid. iaid defaults to the iaid option as de‐\nscribed above. You can request more than one iana by specifying a unique iaid for\neach one.\n\niata [iaid]\nRequest a DHCPv6 Temporary Address for iaid. You can request more than one iata by\nspecifying a unique iaid for each one.\n\niapd [iaid [/ prefix / prefixlen] [interface [/ slaid [/ prefixlen [/ suffix]]]]]\nRequest a DHCPv6 Delegated Prefix for iaid. This option must be used in an interface\nblock. Unless a slaid of 0 is assigned with the same resultant prefix length as the\ndelegation, a reject route is installed for the Delegated Prefix to stop unallocated\naddresses being resolved upstream. If no interface is given then we will assign a\nprefix to every other interface with a slaid equivalent to the interface index as‐\nsigned by the OS. Otherwise addresses are only assigned for each interface and\nslaid. To avoid delegating to any interface, use - as the invalid interface name.\nEach assigned address will have a suffix, defaulting to 1. If the suffix is 0 then a\nSLAAC address is assigned. You cannot assign a prefix to the requesting interface\nunless the DHCPv6 server supports the RFC 6603 Prefix Exclude Option. dhcpcd has to\nbe running for all the interfaces it is delegating to. A default prefixlen of 64 is\nassumed, unless the maximum slaid does not fit. In this case prefixlen is in‐\ncreased to the highest multiple of 8 that can accommodate the slaid. slaid is an\ninteger which must be unique inside the iaid and is added to the prefix which must\nfit inside prefixlen less the length of the delegated prefix. You can specify mul‐\ntiple interface / slaid / prefixlen per iapd, space separated. IPv6RS should be\ndisabled globally when requesting a Prefix Delegation.\n\nIn the following example eth0 is the externally facing interface to be configured for\nboth IPv4 and IPv6. The DHCPv4 server will provide us with an IPv4 address and a de‐\nfault route. The DHCPv6 server is going to provide us with an IPv6 address, a de‐\nfault route and a /64 subnet to be delegated to the internal interface. The eth1 in‐\nterface will be automatically configured for IPv6 using the first address (::1) from\nthe delegated prefix. A second prefix is requested and assigned to two other inter‐\nfaces. rtadvd(8) can be used with an empty configuration file on eth1, eth2 and\neth3, to provide automatic IPv6 address configuration for the internal network.\n\nnoipv6rs # disable routing solicitation\ndenyinterfaces eth2 # Don't touch eth2 at all\ninterface eth0\nipv6rs # enable routing solicitation for eth0\niana 1 # request an IPv6 address\niapd 2 eth1/0 # request a PD and assign it to eth1\niapd 3 eth2/1 eth3/2 # req a PD and assign it to eth2 and eth3\niapd 4 - # request a PD but don't assign it\n" }, { "name": "ipv4only", "content": "Only configure IPv4.\n" }, { "name": "ipv6only", "content": "Only configure IPv6.\n\nfqdn [disable | none | ptr | both]\nnone will not ask the DHCP server to update DNS. ptr just asks the DHCP server to\nupdate the PTR record of the host in DNS, whereas both also updates the A record.\ndisable will disable the FQDN option. The default is both. dhcpcd itself never does\nany DNS updates. dhcpcd encodes the FQDN hostname as specified in RFC 1035.\n\ninterface interface\nSubsequent options are only parsed for this interface.\n" }, { "name": "ipv6ra_autoconf", "content": "Generate SLAAC addresses for each Prefix advertised by an IPv6 Router Advertisement\nmessage with the Auto flag set. On by default.\n" }, { "name": "ipv6ra_noautoconf", "content": "Disables the above option.\n" }, { "name": "ipv6ra_fork", "content": "By default, when dhcpcd receives an IPv6 Router Advertisement, dhcpcd will only fork\nto the background if the RA contains at least one unexpired RDNSS option and a valid\nprefix or no DHCPv6 instruction. Set this option so to make dhcpcd always fork on a\nRA.\n\nipv6rs Enables IPv6 Router Advertisement solicitation. This is on by default, but is docu‐\nmented here in the case where it is disabled globally but needs to be enabled for one\ninterface.\n\nleasetime seconds\nRequest DHCP a lease time of seconds. -1 represents an infinite lease time. By de‐\nfault dhcpcd does not request any lease time and leaves it in the hands of the DHCP\nserver. It is not possible to request a DHCPv6 lease time as this is not RFC compli‐\nant. See RFC 8415 21.4, 21.6, 21.21 and 21.22.\n\nlinkrcvbuf size\nOverride the size of the link receive buffer from the kernel default. While dhcpcd\nwill recover from link buffer overflows, this may not be desirable on heavily loaded\nsystems.\n\nlogfile logfile\nWrites to the specified logfile. dhcpcd still writes to syslog(3). The logfile is\nreopened when dhcpcd receives the SIGUSR2 signal.\n\nmetric metric\nMetrics are used to prefer an interface over another one, lowest wins. dhcpcd will\nsupply a default metric of 1000 + ifnametoindex(3). This will be offset by 2000 for\nwireless interfaces, with additional offsets of 1000000 for IPv4LL and 2000000 for\nroaming interfaces.\n\nmudurl url\nSpecifies the URL for a Manufacturer Usage Description (MUD). The description is\nused by upstream network devices to instantiate any desired access lists. See draft-\nietf-opsawg-mud for more information.\n" }, { "name": "noalias", "content": "Any pre-existing IPv4 addresses will be removed from the interface when adding a new\nIPv4 address.\n\nnoarp Don't send any ARP requests. This also disables IPv4LL.\n" }, { "name": "noauthrequired", "content": "Don't require authentication even though we requested it. Also allows FORCERENEW and\nRECONFIGURE messages without authentication.\n" }, { "name": "nodelay", "content": "Don't delay for an initial randomised time when starting protocols.\n\nnodev Don't load /dev management modules.\n\nnodhcp Don't start DHCP or listen to DHCP messages. This is only useful when allowing\nIPv4LL.\n" }, { "name": "nodhcp6", "content": "Don't start DHCPv6 or listen to DHCPv6 messages. Normally DHCPv6 is started by an\nIPv6 Router Advertisement instruction or configuration.\n" }, { "name": "nogateway", "content": "Don't install any default routes.\n" }, { "name": "gateway", "content": "Install a default route if available (default).\n\nnohook script\nDon't run this hook script. Matches full name, or prefixed with 2 numbers optionally\nending with .sh.\n\nSo to stop dhcpcd from touching your DNS settings or starting wpasupplicant you\nwould do:-\nnohook resolv.conf, wpasupplicant\n\nnoipv4 Don't attempt to configure an IPv4 address.\n" }, { "name": "noipv4ll", "content": "Don't attempt to obtain an IPv4LL address if we failed to get one via DHCP. See RFC\n3927.\n\nnoipv6 Don't solicit or accept IPv6 Router Advertisements and DHCPv6.\n" }, { "name": "noipv6rs", "content": "Don't solicit or accept IPv6 Router Advertisements.\n\nnolink Don't receive link messages about carrier status. You should only set this for buggy\ninterface drivers.\n\nnoup Don't bring the interface up when in manager mode.\n\noption option\nRequests the option from the server. It can be a variable to be used in\ndhcpcd-run-hooks(8) or the numerical value. You can specify more options separated\nby commas, spaces or more option lines. Prepend dhcp6 to option to request a DHCPv6\noption. If no DHCPv6 options are configured, then DHCPv4 options are mapped to\nequivalent DHCPv6 options.\n\nPrepend nd to option to handle ND options, but this only works for the nooption,\nreject and require options.\n\nTo see a list of options you can use, call dhcpcd with the -V, --variables argument.\n\nnooption option\nRemove the option from the message before it's processed.\n\nrequire option\nRequires the option to be present in all messages, otherwise the message is ignored.\nTo enforce that dhcpcd only responds to DHCP servers and not BOOTP servers, you can\nrequire dhcpmessagetype. This isn't an exact science though because a BOOTP server\ncan send DHCP-like options.\n\nreject option\nReject a message that contains the option. This is useful when you cannot use\nrequire to select / de-select BOOTP messages.\n\ndestination option\nIf dhcpcd.conf detects an address added to a point to point interface (PPP, TUN, etc)\nthen it will set the listed DHCP options to the destination address of the interface.\n\nprofile name\nSubsequent options are only parsed for this profile name.\n\nquiet Suppress any dhcpcd output to the console, except for errors.\n\nreboot seconds\nAllow reboot seconds before moving to the DISCOVER phase if we have an old lease to\nuse. Allow reboot seconds before starting fallback states from the DISCOVER phase.\nIPv4LL is started when the first reboot timeout is reached. The default is 5 sec‐\nonds. A setting of 0 seconds causes dhcpcd.conf to skip the reboot phase and go\nstraight into DISCOVER. This is desirable for mobile users because if you change\nfrom network A to network B and they use the same subnet and the address from network\nA isn't in use on network B, then the DHCP server will remain silent even if authori‐\ntative which means dhcpcd will timeout before moving back to the DISCOVER phase.\nThis has no effect on DHCPv6 other than skipping the reboot phase.\n" }, { "name": "release", "content": "dhcpcd will release the lease prior to stopping the interface.\n\nscript script\nUse script instead of the default /usr/lib/dhcpcd/dhcpcd-run-hooks.\n\nssid ssid\nSubsequent options are only parsed for this wireless ssid.\n\nslaac hwaddr | private | token token [temp | temporary]\nSelects the interface identifier used for SLAAC generated IPv6 addresses. If private\nis used, a RFC 7217 address is generated. If token token is used then the token is\ncombined with the prefix to make the final address. The temporary directive will\ncreate a temporary address for the prefix as well.\n\nstatic value\nConfigures a static value. If you set ipaddress then dhcpcd will not attempt to ob‐\ntain a lease and will just use the value for the address with an infinite lease time.\nIf you set an empty value this removes all prior static allocations to the same\nvalue. This is useful when using profiles and in the case of ipaddress it will re‐\nmove the static allocation. Note that setting 0.0.0.0 keeps the static allocation\nbut waits for a 3rdparty to configure the address. If you set ip6address, dhcpcd\nwill continue auto-configuration as normal.\n\nHere is an example which configures two static address, overriding the default IPv4\nbroadcast address, an IPv4 router, DNS and disables IPv6 auto-configuration. You\ncould also use the inform6 command here if you wished to obtain more information via\nDHCPv6. For IPv4, you should use the inform ipaddress option instead of setting a\nstatic address.\ninterface eth0\nnoipv6rs\nstatic ipaddress=192.168.0.10/24\nstatic broadcastaddress=192.168.0.63\nstatic ip6address=fd51:42f8:caae:d92e::ff/64\nstatic routers=192.168.0.1\nstatic domainnameservers=192.168.0.1 fd51:42f8:caae:d92e::1\n\nHere is an example for PPP which gives the destination a default route. It uses the\nspecial destination keyword to insert the destination address into the value.\ninterface ppp0\nstatic ipaddress=0.0.0.0\ndestination routers\n\ntimeout seconds\nTime out after seconds, instead of the default 30. A setting of 0 seconds causes\ndhcpcd to wait forever to get a lease. If dhcpcd is working on a single interface\nthen dhcpcd will exit when a timeout occurs, otherwise dhcpcd will fork into the\nbackground. If using IPv4LL then dhcpcd start the IPv4LL process after the timeout\nand then wait a little longer before really timing out.\n\nuserclass string\nTag the DHCPv4 message with the userclass. You can specify more than one.\n\nmsuserclass string\nTag the DHCPv4 mesasge with the Microsoft userclass. Unlike the userclass option,\nthis one can only be added once. It should only be used for Microsoft DHCP servers\nand the vendorclassid should be set to \"MSFT 98\" or \"MSFT 5.0\". This option is not\nRFC compliant.\n\nvendor code,value\nAdd an encapsulated vendor option. code should be between 1 and 254 inclusive. To\nadd a raw vendor string, omit code but keep the comma. Examples.\n\nSet the vendor option 01 with an IP address.\nvendor 01,192.168.0.2\nSet the vendor option 02 with a hex code.\nvendor 02,01:02:03:04:05\nSet the vendor option 03 with an IP address as a string.\nvendor 03,\\\"192.168.0.2\\\"\nSet un-encapsulated vendor option to hello world.\nvendor ,\"hello world\"\n\nvendorclassid string\nSet the DHCP Vendor Class. DHCPv6 has its own option as shown below. The default is\ndhcpcd-:::. For example\ndhcpcd-5.5.6:NetBSD-6.99.5:i386:i386\nIf not set then none is sent. Some badly configured DHCP servers reject unknown ven‐\ndorclassids. To work around it, try and impersonate Windows by using the MSFT ven‐\ndorclassid.\n\nvendclass en data\nAdd the DHCPv6 Vendor Indetifying Vendor Class with the IANA assigned Enterprise Num‐\nber en with the data. This option can be set more than once to add more data, but\nthe behaviour, as per RFC 3925 is undefined if the Enterprise Number differs.\n\nwaitip [4 | 6]\nWait for an address to be assigned before forking to the background. 4 means wait\nfor an IPv4 address to be assigned. 6 means wait for an IPv6 address to be assigned.\nIf no argument is given, dhcpcd.conf will wait for any address protocol to be as‐\nsigned. It is possible to wait for more than one address protocol and dhcpcd.conf\nwill only fork to the background when all waiting conditions are satisfied.\n" }, { "name": "xidhwaddr", "content": "Use the last four bytes of the hardware address as the DHCP xid instead of a randomly\ngenerated number.\n" }, { "name": "Defining new options", "content": "DHCP, ND and DHCPv6 allow for the use of custom options, and RFC 3925 vendor options for DHCP\ncan also be supplied. Each option needs to be started with the define, definend, define6 or\nvendopt directive. This can optionally be followed by both embed or encap options. Both can\nbe specified more than once and embed must come before encap.\n\ndefine code type variable\nDefines the DHCP option code of type with a name of variable exported to\ndhcpcd-run-hooks(8).\n\ndefinend code type variable\nDefines the ND option code of type with a name of variable exported to\ndhcpcd-run-hooks(8), with a prefix of nd.\n\ndefine6 code type variable\nDefines the DHCPv6 option code of type with a name of variable exported to\ndhcpcd-run-hooks(8), with a prefix of dhcp6.\n\nvendopt code type variable\nDefines the Vendor-Identifying Vendor Options. The code is the IANA Enterprise Num‐\nber which will uniquely describe the encapsulated options. type is normally encap.\nvariable names the Vendor option to be exported.\n\nembed type variable\nDefines an embedded variable within the defined option. The length is determined by\nthe type. If the variable is not the same as defined in the parent option, it is\nprefixed with the parent variable first with an underscore. If the variable has the\nname of reserved then it is not processed.\n\nencap code type variable\nDefines an encapsulated variable within the defined option. The length is determined\nby the type. If the variable is not the same as defined in the parent option, it is\nprefixed with the parent variable first with an underscore.\n" }, { "name": "Type prefix", "content": "These keywords come before the type itself, to describe it more fully. You can use more than\none, but they must appear in the order listed below.\n\nrequest Requests the option by default without having to be specified in user configuration.\n" }, { "name": "norequest", "content": "This option cannot be requested, regardless of user configuration.\n" }, { "name": "optional", "content": "This option is optional. Only makes sense for embedded options like the client FQDN\noption, where the FQDN string itself is optional.\n\nindex The option can appear more than once and will be indexed.\n\narray The option data is split into a space separated array, each element being the same\ntype.\n" }, { "name": "Types to define", "content": "The type directly affects the length of data consumed inside the option. Any remaining data\nis normally discarded. Lengths can be specified for string and binhex types, but this is\ngenerally with other data embedded afterwards in the same option.\n" }, { "name": "ipaddress", "content": "An IPv4 address, 4 bytes.\n" }, { "name": "ip6address", "content": "An IPv6 address, 16 bytes.\n\nstring [: length]\nA NVT ASCII string of printable characters.\n\nbyte A byte.\n\nbitflags: flags\nA byte represented as a string of flags, most significant bit first. For example,\nusing ABCDEFGH then A would equal 10000000, B 01000000, C 00100000, etc. If the bit\nis not set, the flag is not printed. A flag of 0 is not printed even if the bit po‐\nsition is set. This is to allow reservation of the first bits while assigning the\nlast bits.\n\nint16 A signed 16bit integer, 2 bytes.\n\nuint16 An unsigned 16bit integer, 2 bytes.\n\nint32 A signed 32bit integer, 4 bytes.\n\nuint32 An unsigned 32bit integer, 4 bytes.\n\nflag A fixed value (1) to indicate that the option is present, 0 bytes.\n\ndomain An RFC 3397 encoded string.\n\ndname An RFC 1035 validated string.\n\nuri If an array then the first two bytes are the URI length inside the option data. Oth‐\nerwise, the whole option data is the URI. As a space is not allowed in the URI en‐\ncoding, the URIs are space separated.\n\nbinhex [: length]\nBinary data expressed as hexadecimal.\n\nembed Contains embedded options (implies encap as well).\n\nencap Contains encapsulated options (implies embed as well).\n\noption References an option from the global definition.\n" }, { "name": "Example definition", "content": "# DHCP option 81, Fully Qualified Domain Name, RFC 4702\ndefine 81 embed fqdn\nembed byte flags\nembed byte rcode1\nembed byte rcode2\nembed domain fqdn\n\n# DHCP option 125, Vendor Specific Information Option, RFC 3925\ndefine 125 encap vsio\nembed uint32 enterprisenumber\n# Options defined for the enterprise number\nencap 1 ipaddress ipaddress\n" }, { "name": "Supported Authentication Protocols", "content": "token Sends a plain text token the server expects and matches a token sent by the server.\nThe tokens do not have to be the same. If unspecified, the token with a secretid of\n0 will be used in sending messages and validating received messages.\n" }, { "name": "delayedrealm", "content": "Delayed Authentication. dhcpcd will send an authentication option with no key or\nMAC. The server will see this option, and select a key for dhcpcd.conf, writing the\nrealm and secretid in it. dhcpcd will then look for an unexpired token with a\nmatching realm and secretid. This token is used to authenticate all other messages.\n\ndelayed Same as above, but without a realm.\n" }, { "name": "Supported Authentication Algorithms", "content": "If none specified, hmac-md5 is the default.\n" }, { "name": "hmac-md5", "content": "" }, { "name": "Supported Replay Detection Mechanisms", "content": "If none specified, monotonic is the default. If this is changed from what was previously\nused, or the means of calculating or storing it is broken, then the DHCP server will probably\nhave to have its notion of the client's Replay Detection Value reset.\n" }, { "name": "monocounter", "content": "Read the number in the file /var/lib/dhcpcd/dhcpcd-rdm.monotonic and add one to it.\n" }, { "name": "monotime", "content": "Create an NTP timestamp from the system time.\n" }, { "name": "monotonic", "content": "Same as monotime.\n" } ] }, "SEE ALSO": { "content": "fnmatch(3), ifnametoindex(3), dhcpcd(8), dhcpcd-run-hooks(8)\n", "subsections": [] }, "AUTHORS": { "content": "Roy Marples \n", "subsections": [] }, "BUGS": { "content": "Please report them to https://roy.marples.name/projects/dhcpcd\n\nDebian December 18, 2023 DHCPCD.CONF(5)", "subsections": [] } }, "summary": "dhcpcd.conf — dhcpcd configuration file", "flags": [], "examples": [], "see_also": [ { "name": "fnmatch", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/fnmatch/3/json" }, { "name": "ifnametoindex", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/ifnametoindex/3/json" }, { "name": "dhcpcd", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/dhcpcd/8/json" }, { "name": "dhcpcd-run-hooks", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/dhcpcd-run-hooks/8/json" } ] }