NAME

hostapd — Host Access Point daemon

SYNOPSIS

DESCRIPTION

hostapd is a daemon which allows communication between different 802.11 wireless access points running in Host AP mode.

hostapd 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.

hostapd additionally allows the monitoring and logging of station associations on a non-hostap host which is receiving IAPP messages.

hostapd uses two network interfaces on startup specified in the configuration file hostapd.conf(5). The first interface is used to access the Host AP, which is a wireless interface running in Host AP mode. Host AP mode can be enabled using ifconfig(8). The second interface is used to communicate with other hostapd in the same broadcast domain or multicast group. Usually a wired interface is used to communicate with other hostapd.

hostapd broadcasts an ADD.notify IAPP message when a new station is associated to the Host AP. When hostapd receives an ADD.notify message, it tells the Host AP to remove the specified station.

hostapd may also handle dynamic roaming of IP addresses and routes in addition to the standard IAPP ADD.notify behaviour. See the section called IP Roaming in hostapd.conf(5) for details.

The options are as follows:

-D macro=value

Define macro to be set to value on the command line. Overrides the definition of macro in the configuration file.

-d

Do not daemonize and log to stderr.

-f file

Use file as the configuration file, instead of the default /etc/hostapd.conf.

-v

Produce more verbose output.

FILES

/etc/hostapd.conf

default hostapd configuration file

SEE ALSO

hostapd.conf(5), ifconfig(8)

Inter Access Point Protocol, IEEE 802.11f, March 2001.

HISTORY

The hostapd program first appeared at the 21st Chaos Communication Congress (https://events.ccc.de/congress/2004/) and later in OpenBSD 3.8.

AUTHORS

The hostapd program was written by Reyk Floeter <reyk@openbsd.org>.

CAVEATS

hostapd depends on drivers using the net80211 kernel wireless layer with support of Host AP mode. For traditional reasons, the wi(4) driver still uses its own Host AP code in if_wi_hostap(), which is not supported by hostapd.

The IEEE 802.11 WLAN protocol lacks authentication of management frames and is vulnerable to various denial of service and man-in-the-middle attacks. That should be considered when implementing wireless networks with hostapd.