DESCRIPTION
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
arping 192.168.0.1
profile 192.168.0.1
static ip_address=192.168.0.10/24
-
background
-
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.
-
broadcast
-
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.
-
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.
-
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 clientid. This requires persistent storage and not all DHCP servers work with it so it's not enabled by default. The duid generated will be held in /etc/dhcpcd.duid and should not be copied to other hosts.
-
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.
-
fqdn [none | ptr | both]
-
none disables FQDN encoding, ptr just asks the DHCP server to update the PTR record of the host in DNS whereas both also updates the A record. 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.
-
ipv6ra_fork
-
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. Set this option so to make dhcpcd always fork on an RA.
-
ic ipv6ra_own
-
Disables kernel IPv6 Router Advertisment processing so dhcpcd can manage addresses and routes.
-
ic ipv6ra_own_default
-
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.
-
ic 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 interfaces.
-
noarp
-
Don't send any ARP requests. This also disables IPv4LL.
-
nogateway
-
Don't install any default routes.
-
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
-
noipv4ll
-
Don't attempt to obtain an IPv4LL address if we failed to get one via DHCP. See RFC 3927.
-
noipv6rs
-
Disable solicition 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.
-
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. The default is 5 seconds. A setting if 0 seconds causes dhcpcd to skip the reboot phase and go straight into discover.
-
release
-
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.
-
script script
-
Use script instead of the default /libexec/dhcpcd-run-hooks.
-
ssid ssid
-
Subsequent options are only parsed for this wireless ssid.
-
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 dns.
interface eth0
static ip_address=192.168.0.10/24
static routers=192.168.0.1
static domain_name_servers=192.168.0.1
Here is an example for PPP which gives the destination a default route. It uses the special destination keyword to insert the destination address into the value.
interface ppp0
static ip_address=
destination routers
-
timeout seconds
-
The default timeout for waiting for a DHCP response is 30 seconds which may be too long or too short and can be changed here.
-
userclass string
-
Tag the DHCP 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 01,192.168.0.2
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,\"192.168.0.2\"
Set un-encapsulated vendor option to hello world.
vendor ,"hello world"
-
vendorclassid string
-
The default is dhcpcd-<version>:<os>:<machine>:<platform>. For example
dhcpcd-5.5.6:NetBSD-6.99.5:i386:i386
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.
-
waitip
-
Wait for an address to be assigned before forking to the background.
-
xidhwaddr
-
Use the last four bytes of the hardware address as the DHCP xid instead of a randomly generated number.