path: root/dhcpcd.conf.5.in

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.Dd March 10, 2009
.Dt DHCPCD.CONF 5 SMM
.Os
.Sh NAME
.Nm dhcpcd.conf
.Nd dhcpcd configuration file 
.Sh DESCRIPTION
Although
.Nm 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
.Xr 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.
.Pp
Blank lines and lines starting with # are ignored.
.Pp
Here's a list of available options:
.Bl -tag -width indent
.It Ic allowinterfaces Ar pattern
When discovering interfaces, the interface name must match
.Ar pattern
which is a space or comma separated list of patterns passed to
.Xr fnmatch 3 .
If the same interface is matched in
.Ic denyinterfaces
then it is still denied.
.It Ic denyinterfaces Ar pattern
When discovering interfaces, the interface name must not match
.Ar pattern
which is a space or comma separated list of patterns passed to
.Xr fnmatch 3 .
.It Ic background
Background immediately.
This is useful for startup scripts which don't disable link messages for
carrier status.
.It Ic blacklist Ar address Ns Op Ar /cidr
Ignores all packets from
.Ar address Ns Op Ar /cidr .
.It Ic clientid Ar string
Send the
.Ar 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
.Ar clientid
is an empty string then
.Nm dhcpcd
sends a default
.Ar clientid
of the hardware family and the hardware address.
.It Ic duid
Generate an
.Rs
.%T "RFC 4361"
.Re
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
.Pa @SYSCONFDIR@/dhcpcd.duid
and should not be copied to other hosts.
.It Ic hostname Ar name
Sends specified
.Ar hostname 
to the DHCP server so it can be registered in DNS. If
.Ar hostname
if a FQDN (ie, contains a .) then it will be encoded as such.
.It Ic fqdn Op 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.
.Nm dhcpcd
itself never does any DNS updates.
.Nm dhcpcd
encodes the FQDN hostname as specified in
.Li RFC1035 .
.It Ic interface Ar interface
Subsequent options are only parsed for this
.Ar interface .
.It Ic leasetime Ar seconds
Request a leasetime of
.Ar seconds .
.It Ic metric Ar metric
Metrics are used to prefer an interface over another one, lowest wins.
.Nm dhcpcd
will supply a default metic of 200 +
.Xr if_nametoindex 3 .
An extra 100 will be added for wireless interfaces.
.It Ic noarp
Don't send any ARP requests.
This also disables IPv4LL.
.It Ic nogateway
Don't install any default routes.
.It Ic nohook Ar script
Don't run this hook script.
Matches full name, or prefixed with 2 numbers optionally ending with
.Pa .sh .
.Pp
So to stop
.Nm dhcpcd
from touching your DNS or MTU settings you would do:-
.D1 nohook resolv.conf, mtu
.It Ic noipv4ll
Don't attempt to obtain an IPv4LL address if we failed to get one via DHCP.
See
.Rs
.%T "RFC 3927"
.Re
.It Ic nolink
Don't receive link messages about carrier status.
You should only set this for buggy interface drivers.
.It Ic option Ar option
Requests the
.Ar option
from the server.
It can be a variable to be used in
.Xr dhcpcd-run-hooks 8
or the numerical value.
You can specify more options seperated by commas, spaces or more option lines.
.Ic quiet
Supress any dhcpcd output to the console, except for errors.
.Ic reboot Ar seconds
Allow
.Ar reboot
seconds before moving to the discover phase if we have an old lease to use.
The default is 10 seconds.
A setting if 0 seconds causes
.Nm dhcpcd
to skip the reboot phase and go straight into discover.
.It Ic release
.Nm dhcpcd
will release the lease prior to stopping the interface.
.It Ic require Ar option
Requires the
.Ar option
to be present in all DHCP messages, otherwise the message is ignored.
It can be a variable to be used in
.Xr dhcpcd-run-hooks 8
or the numerical value.
You can specify more options seperated by commas, spaces or more require lines.
To enforce that
.Nm dhcpcd
only responds to DHCP servers and not BOOTP servers, you can
.Ic require
.Ar dhcp_message_type .
.It Ic script Ar script
Use
.Ar script
instead of the default
.Pa @SCRIPT@ .
.It Ic ssid Ar ssid
Subsequent options are only parsed for this wireless
.Ar ssid .
.It Ic static Ar value
Configures a static
.Ar value .
If you set
.Ic ip_address
then
.Nm dhcpcd
will not attempt to obtain a lease and just use the value for the address with
an infinite lease time.
.Pp
Here is an example which configures a static address, routes and dns.
.D1 interface eth0
.D1 static ip_address=192.168.0.10/24
.D1 static routers=192.168.0.1
.D1 static domain_name_servers=192.168.0.1
.It Ic timeout Ar 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.
.It Ic userclass Ar string
Tag the DHCP messages with the userclass.
You can specify more than one.
.It Ic vendor Ar code , Ns Ar value
Add an enscapulated vendor option.
.Ar code
should be between 1 and 254 inclusive.
Examples.
.Pp
Set the vendor option 01 with an IP address.
.D1 vendor 01,192.168.0.2
Set the vendor option 02 with a hex code.
.D1 vendor 02,01:02:03:04:05
Set the vendor option 03 with an IP address as a string.
.D1 vendor 03,\e"192.168.0.2\e"
.It Ic vendorclassid Ar string
Change the default vendorclassid sent from dhcpcd-version.
If not set then none is sent.
.El
.Sh SEE ALSO
.Xr dhcpcd-run-hooks 8 ,
.Xr dhcpcd 8 ,
.Xr if_nametoindex 3 ,
.Xr fnmatch 3
.Sh AUTHORS
.An Roy Marples Aq roy@marples.name
.Sh BUGS
Please report them to http://roy.marples.name/projects/dhcpcd