RESOLVCONF(8) System Manager's Manual RESOLVCONF(8)NAME
resolvconf — a framework for managing multiple DNS configurations
SYNOPSIS
resolvconf -I
resolvconf [-m metric] [-p] -a interface <file
resolvconf [-f] -d interface
resolvconf -il pattern
resolvconf -u
DESCRIPTION
resolvconf manages resolv.conf(5) files from multiple sources, such as
DHCP and VPN clients. Traditionally, the host runs just one client and
that updates /etc/resolv.conf. More modern systems frequently have wired
and wireless interfaces and there is no guarantee both are on the same
network. With the advent of VPN and other types of networking daemons,
many things now contend for the contents of /etc/resolv.conf.
resolvconf solves this by letting the daemon send their resolv.conf(5)
file to resolvconf via stdin(3) with the argument -a interface instead of
the filesystem. resolvconf then updates /etc/resolv.conf as it thinks
best. When a local resolver other than libc is installed, such as
dnsmasq(8) or named(8), then resolvconf will supply files that the
resolver should be configured to include.
resolvconf can mark an interfaces resolv.conf as private. This means
that the name servers listed in that resolv.conf are only used for
queries against the domain/search listed in the same file. This only
works when a local resolver other than libc is installed. See
resolvconf.conf(5) for how to configure resolvconf to use a local name
server.
When an interface goes down, it should then call resolvconf with -d
interface arguments to delete the resolv.conf file for the interface.
Here are some more options that resolvconf has:-
-I Initialise the state directory /var/run/resolvconf. This only
needs to be called if the initial system boot sequence does not
automatically clean it out; for example the state directory is
moved somewhere other than /var/run. If used, it should only be
called once as early in the system boot sequence as possible and
before resolvconf is used to add interfaces.
-f Ignore non existant interfaces. Only really useful for deleting
interfaces.
-i pattern
List the interfaces, optionally matching pattern, we have
resolv.conf files for.
-l pattern
List the resolv.conf files we have. If pattern is specified then
we list the files for the interfaces that match it.
-m metric
Set the metric of the interface when adding it, default of 0.
Lower metrics take precedence. This affects the default order of
interfaces when listed.
-p Marks the interface resolv.conf as private.
-u Force resolvconf to update all it's subscribers. resolvconf does
not update the subscribers when adding a resolv.conf that matches
what it already has for that interface.
resolvconf also has some options designed to be used by it's sub‐
scribers:-
-v Echo variables DOMAINS, SEARCH and NAMESERVERS so that the sub‐
scriber can configure the resolver easily.
INTERFACE ORDERING
For resolvconf to work effectively, it has to process the resolv.confs
for the interfaces in the correct order. resolvconf first processes
interfaces from the interface_order list, then interfaces without a metic
and that match the dynamic_order list, then interfaces with a metric in
order and finally the rest in the operating systems lexical order. See
resolvconf.conf(5) for details on these lists.
IMPLEMENTATION NOTES
If a subscriber has the executable bit then it is executed otherwise it
is assumed to be a shell script and sourced into the current environment
in a subshell. This is done so that subscribers can remain fast, but are
also not limited to the shell language.
Portable subscribers should not use anything outside of /bin and /sbin
because /usr and others may not be available when booting. Also, it
would be unwise to assume any shell specific features.
ENVIRONMENT
IF_METRIC
If the -m option is not present then we use IF_METRIC for the metric.
IF_PRIVATE
Marks the interface resolv.conf as private.
FILES
/etc/resolvconf.conf
Configuration file for resolvconf.
/libexec/resolvconf
Directory of subscribers which are run every time resolvconf adds,
deletes or updates.
/libexec/resolvconf/libc.d
Directory of subscribers which are run after the libc subscriber is run.
/var/run/resolvconf
State directory for resolvconf.
HISTORY
This implementation of resolvconf is called openresolv and is fully com‐
mand line compatible with Debian's resolvconf, as written by Thomas Hood.
SEE ALSOresolv.conf(5), resolvconf.conf(5), resolver(3), stdin(3)AUTHORS
Roy Marples ⟨roy@marples.name⟩
BUGS
Please report them to http://roy.marples.name/projects/openresolv
resolvconf does not validate any of the files given to it.
When running a local resolver other than libc, you will need to configure
it to include files that resolvconf will generate. You should consult
resolvconf.conf(5) for instructions on how to configure your resolver.
BSD May 13, 2011 BSD
