RESOLVCONF(8)               System Manager's Manual              RESOLVCONF(8)

NAME
     resolvconf - a framework for managing multiple DNS configurations

SYNOPSIS
     resolvconf -I
     resolvconf [-m metric] [-p] [-x] -a interface[.protocol] <file
     resolvconf -C pattern
     resolvconf -c pattern
     resolvconf [-f] -d interface[.protocol]
     resolvconf [-x] -il pattern
     resolvconf -u
     resolvconf --version

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(4) with the argument -a interface[.protocol]
     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 assumes it has a job to do.  In some situations resolvconf
     needs to act as a deterrent to writing to /etc/resolv.conf.  Where this
     file cannot be made immutable or you just need to toggle this behaviour,
     resolvconf can be disabled by adding resolvconf=NO to resolvconf.conf(5).

     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 and how to remove the private marking.

     resolvconf can mark an interfaces resolv.conf as exclusive.  Only the
     latest exclusive interface is used for processing, otherwise all are.

     When an interface goes down, it should then call resolvconf with -d
     interface.* arguments to delete the resolv.conf file(s) for all the
     protocols on the interface.  For systems that support the concept of
     persisting configuration when the carrier goes down, then it should
     instead call resolvconf with -C interface.* arguments to deprecate the
     matching interfaces and -c interface.* to activate the matching
     interfaces when the carrier comes up.  This only affects the order in
     which interfaces are processed.

     Here are some options for the above commands:-

     -f           Ignore non existent interfaces.  Only really useful for
                  deleting interfaces.

     -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.

     -x           Mark the interface resolv.conf as exclusive when adding,
                  otherwise only use the latest exclusive interface.

     resolvconf has some more commands for general usage:-

     -i pattern   List the interfaces and protocols, 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 and protocols that
                  match it.

     -u           Force resolvconf to update all its subscribers.  resolvconf
                  does not update the subscribers when adding a resolv.conf
                  that matches what it already has for that interface.

     --version    Echo the resolvconf version to stdout.

     resolvconf also has some commands designed to be used by its subscribers
     and system startup:-

     -I           Initialise the state directory /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.

     -R           Echo the command used to restart a service.

     -r service   If the service is running then restart it.  If the service
                  does not exist or is not running then zero is returned,
                  otherwise the result of restarting the service.

     -v           Echo variables DOMAINS, SEARCH and NAMESERVERS so that the
                  subscriber can configure the resolver easily.

     -V           Same as -v except that only the information configured in
                  resolvconf.conf(5) is set.

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
     metric 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.

PROTOCOLS
     Here are some suggested protocol tags to use for each resolv.conf file
     registered on an interface:-

     dhcp         Dynamic Host Configuration Protocol.  Initial versions of
                  resolvconf did not recommend a protocol tag be appended to
                  the interface name.  When the protocol is absent, it is
                  assumed to be the DHCP protocol.

     ppp          Point-to-Point Protocol.

     ra           IPv6 Router Advertisement.

     dhcp6        Dynamic Host Configuration Protocol, version 6.

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.

     IF_EXCLUSIVE
     Marks the interface resolv.conf as exclusive.

FILES
     /etc/resolv.conf.bak
     Backup file of the original resolv.conf.

     /etc/resolvconf.conf
     Configuration file for resolvconf.

     /usr/lib/resolvconf
     Directory of subscribers which are run every time resolvconf adds,
     deletes or updates.

     /usr/lib/resolvconf/libc.d
     Directory of subscribers which are run after the libc subscriber is run.

     /run/resolvconf
     State directory for resolvconf.

SEE ALSO
     resolver(3), stdin(4), resolv.conf(5), resolvconf.conf(5)

HISTORY
     This implementation of resolvconf is called openresolv and is fully
     command line compatible with Debian's resolvconf, as written by Thomas
     Hood.

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.

Linux 6.7.4-arch1-1            December 23, 2016           Linux 6.7.4-arch1-1