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.Dd March 14, 2009
.Dt RESOLVCONF 8 SMM
.Os
.Sh NAME
.Nm resolvconf
.Nd a framework for managing multiple DNS configurations
.Sh SYNOPSIS
.Nm
.Op Fl m Ar metric
.Op Fl p
.Fl a Ar interface No < Ns Pa file
.Nm
.Op Fl f
.Fl d Ar interface
.Nm
.Fl il Ar pattern
.Nm
.Fl u
.Sh DESCRIPTION
.Nm
manages
.Xr resolv.conf 5
files from multiple sources, such as DHCP and VPN clients.
Traditionally, the host runs just one client and that updates
.Pa /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
.Pa /etc/resolv.conf .
.Pp
.Nm
solves this by letting the daemon send their
.Xr resolv.conf 5
file to
.Nm
via
.Xr stdin 3
with the argument
.Fl a Ar interface
instead of the filesystem.
.Nm
then updates
.Pa /etc/resolv.conf
as it thinks best.
When a local resolver other than libc is installed, such as
.Xr dnsmasq 8
or
.Xr named 8
then
.Nm
will supply files that the resolver should be configured to include.
.Pp
.Nm
can mark an interfaces
.Pa resolv.conf
as private.
This means that the nameservers listed in that
.Pa 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.
Doing this, you would probably want
.Nm
to always configure
.Pa /etc/resolv.conf
with the local nameserver.
See
.Pa @SYSCONFDIR@/resolv.conf.base
below on how to do this.
.Pp
When an interface goes down, it should then call
.Nm
with
.Fl d Ar interface
arguments to delete the
.Pa resolv.conf
file for the
.Ar interface .
.Pp
Here are some more options that
.Nm
has:-
.Bl -tag -width indent
.It Fl f
Ignore non existant interfaces.
Only really useful for deleting interfaces.
.It Fl i Ar pattern
List the interfaces, optionally matching
.Ar pattern ,
we have
.Pa resolv.conf
files for.
.It Fl l Ar pattern
List the
.Pa resolv.conf
files we have.
If
.Ar pattern
is specified then we list the files for the interfaces that match it.
.It Fl m Ar 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.
.It Fl p
Marks the interface
.Pa resolv.conf
as private.
.It Fl u
Force
.Nm
to update all it's helpers.
.Nm
does not update the helpers when adding a resolv.conf that matches
what it already has for that interface.
.El
.Pp
.Nm
also has some options designed to be used by it's helpers:-
.Bl -tag -width indent
.It Fl s Ar service Ar command ...
Try and send the
.Ar command
to the system
.Ar service .
Normally this is something like
.Ar resolvconf -s named restart .
We have this command, so the helpers don't have to know too much about the
operating system on the host.
.It Fl v
Echo variables DOMAINS, SEARCH and NAMESERVERS so that the helper can configure
the resolver easily.
.El
.Sh ENVIRONMENT
.Bl -ohang
.It Va IF_METRIC
If the
.Fl m
option is not present then we use
.Va IF_METRIC
for the metric.
.It Va IF_PRIVATE
Marks the interface
.Pa resolv.conf
as private.
.El
.Sh FILES
.Bl -ohang
.It Pa @SYSCONFDIR@/interface-order
Determines the order in which nameserver information records are processed
by resolvconf -l.
.It Pa @SYSCONFDIR@/private-interfaces
A list of interfaces who should be marked as private by default.
.It Pa @SYSCONFDIR@/resolv.conf.base
Contains basic resolver information which is included in
.Pa /etc/resolv.conf
even when no interfaces are configured.
This is a good place to set libc to always use your local nameserver like so:
.Bd -literal -offset indent
nameserver 127.0.0.1
.Ed
.It Pa @SYSCONFDIR@/resolv.conf.head
File to be prepended to
.Pa /etc/resolv.conf .
Normally this is just a comment line.
.It Pa @SYSCONFDIR@/resolv.conf.tail
File to be appended to
.Pa /etc/resolv.conf .
.It Pa @VARBASE@/run/resolvconf
Directory that holds the data for
.Nm .
.It Pa @LIBEXECDIR@
Directory of the helper scripts which are run every time
.Nm
adds, deletes or updates.
.It Pa @LIBEXECDIR@/libc.d
Directory of helper scripts which are run after the libc helper script is run.
.El
.Sh HISTORY
This implementation of
.Nm
is called openresolv and is fully command line compatible with Debian's
resolvconf, as written by Thomas Hood, on which openresolv is based.
.Pp
The Debian version only works with bash and other GNU userland tools, whereas
openresolv works with a POSIX shell and userland tools.
.Sh BUGS
.Nm
does not validate any of the files given to it.
.Pp
When running a local resolver other than libc, you will need to configure it
to include files that
.Nm
will generate.
You should consult the comment section in the helper script
for your resolver found in @LIBEXECDIR@ for instructions
on this.
.Sh SEE ALSO
.Xr dnsmasq 8 ,
.Xr named 8 ,
.Xr resolv.conf 5 ,
.Xr resolver 3 ,
.Xr stdin 3
.Sh AUTHORS
.An Roy Marples Aq roy@marples.name
.Sh BUGS
Please report them to http://roy.marples.name/projects/openresolv