.\" $OpenBSD: hostapd.8,v 1.8 2005/04/18 04:05:25 jolan Exp $
.\"
.\" Copyright (c) 2004, 2005 Reyk Floeter <reyk@vantronix.net>
.\"
.\" 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.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd November 13, 2004
.Dt HOSTAPD 8
.Os
.Sh NAME
.Nm hostapd
.Nd Host Access Point daemon
.Sh SYNOPSIS
.Nm hostapd
.Op Fl bdv
.Op Fl a Ar interface
.Oo Xo
.Fl D Ar macro Ns = Ns Ar value Oc
.Xc
.Op Fl f Ar file
.Op Fl i Ar interface
.Sh DESCRIPTION
.Nm
is a daemon which allows communication between different 802.11
wireless access points running in
.Em Host AP
mode.
.Pp
.Nm
implements the Inter Access Point Protocol (IAPP).
Its purpose is to exchange station association updates between access
points in large wireless networks.
IAPP has been designed to speed up roaming between different access
points in the same Extended Service Set (ESS).
IAPP is described in the IEEE 802.11f standard.
.Pp
.Nm
additionally allows the monitoring and logging of station associations on a
non-hostap host which is receiving IAPP messages.
.Pp
.Nm
uses two network interfaces as options on startup.
The first interface,
specified using the
.Fl a
flag,
is used to access the Host AP,
which is a wireless interface running in Host AP mode.
Host AP mode can be enabled using
.Xr ifconfig 8 .
The second interface is used to communicate with other
.Nm
in the same broadcast domain or multicast group.
Usually a wired interface is used to communicate with other
.Nm .
.Pp
The
.Nm
will send an
.Em ADD.notify
IAPP message if a new station has been associated successfully to the Host AP.
If the
.Nm
receives ADD.notify messages it will request the Host AP
remove a station which has been associated to another access point.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl a Ar interface
Specify the 802.11 wireless network interface running in Host AP mode.
This option could be omitted to use the
.Nm
to log received
.Pa IAPP
messages.
.It Fl b
Use UDP broadcast instead of multicast group 224.0.1.178 for IAPP
messages.
.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 and log to
.Em stderr .
.It Fl f Ar file
Use
.Ar file
as the configuration file, instead of the default
.Pa /etc/hostapd.conf .
.It Fl i Ar interface
Specify the network interface used to send
.Pa IAPP
messages.
It is important that the IAPP interface is on a trusted
network because there is no authentication and an attacker could force
disassociation of selected stations on all listening access points.
.It Fl v
Produce more verbose output.
.El
.Sh FILES
.Bl -tag -width "/etc/hostapd.confXXX" -compact
.It Pa /etc/hostapd.conf
default
.Nm
configuration file
.El
.Sh SEE ALSO
.Xr hostapd.conf 5 ,
.Xr ifconfig 8
.Rs
.%R IEEE 802.11f
.%T Inter Access Point Protocol
.%D March 2001
.Re
.Sh HISTORY
The
.Nm
program first appeared at the 21st Chaos Communication Congress
(http://www.ccc.de/congress/2004/) and later in
.Ox 3.8 .
.Sh AUTHORS
The
.Nm
program was written by
.An Reyk Floeter Aq reyk@openbsd.org .
.Sh CAVEATS
.Nm
depends on drivers using the net80211
kernel wireless layer with support of Host AP mode.
For traditional reasons,
the
.Xr wi 4
driver still uses its own Host AP code in
.Fn if_wi_hostap ,
which is not supported by
.Nm .