OpenBSD-4.6/usr.sbin/relayd/relayd.8

.\"	$OpenBSD: relayd.8,v 1.17 2008/05/07 01:49:29 reyk Exp $
.\"
.\" Copyright (c) 2006 Pierre-Yves Ritschard <pyr@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.Dd $Mdocdate: May 7 2008 $
.Dt RELAYD 8
.Os
.Sh NAME
.Nm relayd
.Nd relay daemon
.Sh SYNOPSIS
.Nm
.Op Fl dnv
.Oo Xo
.Fl D Ar macro Ns = Ns Ar value Oc
.Xc
.Op Fl f Ar file
.Sh DESCRIPTION
.Nm
is a daemon to relay and dynamically redirect incoming connections to
a target host.
Its main purposes are to run as a load-balancer, application layer
gateway, or transparent proxy.
The daemon is able to monitor groups of hosts for availability, which
is determined by checking for a specific service common to a host
group.
When availability is confirmed,
Layer 3 and/or layer 7 forwarding services are set up by
.Nm .
.Pp
Layer 3 redirection happens at the packet level; to configure
it,
.Nm
communicates with
.Xr pf 4 .
To allow
.Nm
to properly set up
.Xr pf 4
rules, the following lines are required in the NAT and filter sections of
.Xr pf.conf 5 :
.Bd -literal -offset indent
rdr-anchor "relayd/*"
anchor "relayd/*"
.Ed
.Pp
Layer 7 relaying happens at the application level and is
handled by
.Nm
itself.
Various application level filtering and protocol-specific
load-balancing options are available for relays.
.Pp
.Nm
works in terms of the following
.Em entities :
relays, protocols, redirections, and tables.
A
.Em relay
represents a layer 7 load-balancing instance.
Each instance translates to a listening TCP or UDP port.
A
.Em protocol
defines which actions, if any, are taken on the
packet payload as data crosses a relay.
A
.Em redirection
represents a layer 3 load-balancing instance.
Each instance translates to a
.Xr pf 4
rdr rule being added.
A
.Em table
represents a group of hosts which can be checked for
availability using the same method.
Each table contains at least one host.
If a table is used in a layer 3 load-balancing instance, it
will be mapped to a
.Xr pf 4
table containing only those hosts which are up.
.Pp
All these entities can be configured in
.Xr relayd.conf 5 ,
and
.Xr relayctl 8
can be used to alter or report on the status of each entity.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl D Ar macro Ns = Ns Ar value
Define
.Ar macro
to be set to
.Ar value
on the command line.
Overrides the definition of
.Ar macro
in the configuration file.
.It Fl d
Do not daemonize.
If this option is specified,
.Nm
will run in the foreground and log to
.Em stderr .
.It Fl f Ar file
Specify an alternative configuration file.
The default is
.Pa /etc/relayd.conf .
.It Fl n
Configtest mode.
Only check the configuration file for validity.
.It Fl v
Produce more verbose output.
.El
.Sh FILES
.Bl -tag -width "/var/run/relayd.sockXX" -compact
.It /etc/relayd.conf
Default configuration file.
.It /var/run/relayd.sock
Unix-domain socket used for communication with
.Xr relayctl 8 .
.El
.Sh SEE ALSO
.Xr relayd.conf 5 ,
.Xr relayctl 8
.Sh HISTORY
The
.Nm
program, formerly known as
.Ic hoststated ,
first appeared in
.Ox 4.1 .
It was renamed to
.Nm
in
.Ox 4.3 .
.Sh AUTHORS
.An -nosplit
The
.Nm
program was written by
.An Pierre-Yves Ritschard Aq pyr@openbsd.org
and
.An Reyk Floeter Aq reyk@openbsd.org .