.TH "DNSDIST" "1" "2013 \- 2016" "" ""
.SH NAME
.PP
\f[B]dnsdist\f[] \- tool to balance DNS queries over downstream servers
.SH SYNOPSIS
.PP
dnsdist [\f[I]OPTION\f[]]...
\f[I]ADDRESS\f[]...
.SH DESCRIPTION
.PP
\f[B]dnsdist\f[] receives DNS queries and relays them to one or more
downstream servers.
It subsequently sends back responses to the original requestor.
.PP
dnsdist operates over TCP and UDP, and strives to deliver very high
performance over both.
.PP
Currently, queries are sent to the downstream server with the least
outstanding queries.
This effectively implies load balancing, making sure that slower servers
get less queries.
.PP
If a reply has not come in after a few seconds, it is removed from the
queue, but in the short term, timeouts do cause a server to get less
traffic.
.PP
IPv4 and IPv6 operation can be mixed and matched, in other words,
queries coming in over IPv6 could be forwarded to IPv4 and vice versa.
.PP
\f[B]dnsdist\f[] is scriptable in Lua, see the dnsdist documentation for
more information on this.
.SH SCOPE
.PP
dnsdist does not \[aq]think\[aq] about DNS queries, it restricts itself
to measuring response times and error codes and routing questions
accordingly.
It comes with a very high performance packet\-cache.
.PP
The goal for dnsdist is to remain simple.
If more powerful loadbalancing is required, dedicated hardware or
software is recommended.
Linux Virtual Server for example is often mentioned.
.SH OPTIONS
.TP
.B \-a,\-\-acl \f[I]NETMASK\f[]
Add \f[I]NETMASK\f[] to the ACL.
.RS
.RE
.TP
.B \-C,\-\-config \f[I]FILE\f[]
Load configuration from \f[I]FILE\f[].
.RS
.RE
.TP
.B \-\-check\-config
Test the configuration file (which may be set with \f[B]\-\-config\f[]
or \f[B]\-C\f[]) for errors.
dnsdist will show the errors and exit with a non\-zero exit\-code when
errors are found.
.RS
.RE
.TP
.B \-c,\-\-client [\f[I]ADDRESS\f[][:\f[I]PORT\f[]]]
Operate as a client, connect to dnsdist.
This will read the dnsdist configuration for the \f[B]controlSocket\f[]
statement and connect to it.
When \f[I]ADDRESS\f[] (with optional \f[I]PORT\f[]) is set, dnsdist will
connect to that instead.
.RS
.RE
.TP
.B \-k,\-\-setkey \f[I]KEY\f[]
When operating as a client(\f[B]\-c\f[], \f[B]\-\-client\f[]), use
\f[I]KEY\f[] as shared secret to connect to dnsdist.
This should be the same key that is used on the server (set with
\f[B]setKey()\f[]).
Note that this will leak the key into your shell\[aq]s history.
Only available when dnsdist is compiled with libsodium support.
.RS
.RE
.TP
.B \-d,\-\-daemon
Operate as a daemon.
.RS
.RE
.TP
.B \-e,\-\-execute \f[I]CMD\f[]
Connect to dnsdist and execute \f[I]CMD\f[].
.RS
.RE
.TP
.B \-h,\-\-help
Display a helpful message and exit.
.RS
.RE
.TP
.B \-l,\-\-local \f[I]ADDRESS\f[]
Bind to \f[I]ADDRESS\f[], Supply as many addresses (using multiple
\f[B]\-\-local\f[] statements) to listen on as required.
Specify IPv4 as 0.0.0.0:53 and IPv6 as [::]:53.
.RS
.RE
.TP
.B \-\-supervised
Run in foreground, but do not spawn a console.
Use this switch to run dnsdist inside a supervisor (use with e.g.
systemd and daemontools).
.RS
.RE
.TP
.B \-\-disable\-syslog
Disable logging to syslog.
Use this when running inside a supervisor that handles logging (like
systemd).
Do not use in combination with \f[B]\-\-daemon\f[].
.RS
.RE
.TP
.B \-p,\-\-pidfile \f[I]FILE\f[]
Write a pidfile to \f[I]FILE\f[], works only with \f[B]\-\-daemon\f[].
.RS
.RE
.TP
.B \-u,\-\-uid \f[I]UID\f[]
Change the process user to \f[I]UID\f[] after binding sockets.
\f[I]UID\f[] can be a name or number.
.RS
.RE
.TP
.B \-g,\-\-gid \f[I]GID\f[]
Change the process group to \f[I]GID\f[] after binding sockets.
\f[I]GID\f[] Can be a name or number.
.RS
.RE
.TP
.B \-V,\-\-version
Show the dnsdist version and exit.
.RS
.RE
.TP
.B \-v,\-\-verbose
Be verbose.
.RS
.RE
.TP
.B ADDRESS
Any number of downstream DNS servers, in the same syntax as used with
\f[B]\-\-local\f[].
If the port is not specified, 53 is used.
.RS
.RE
.SH BUGS
.PP
Right now, the TCP support has some rather arbitrary limits.
.SH RESOURCES
.PP
Website: http://dnsdist.org
.SH AUTHORS
PowerDNS.com BV.