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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 /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.
-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.
/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.
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.
NetBSD 10.99 December 23, 2016 NetBSD 10.99