D. Adam Karim shares his solution to using multiple wireless networks:

Having to jump to various wireless network all the time, I have been forced to come up with a way to keep track of them all and make it as seamless as possible to use one or another. The other feature that I wanted was to be able to keep the base files unchanged as much as possible.

Basically, what I have done was create two files, /etc/rc.wireless and /etc/rc.wireless.conf. These two files handle setting up a hostname.if(5) files for the given device based on the configuration in /etc/rc.wireless.conf. One must also add just a small bit to /etc/netstart in order to get it started.

Here is the diff for /etc/netstart as well as the two files:

--- /usr/src/etc/netstart       Wed Aug  1 21:21:27 2007
+++ /etc/netstart       Thu Dec 20 15:22:18 2007
@@ -2,6 +2,11 @@
 #
 #      $OpenBSD: netstart,v 1.116 2007/08/02 03:19:10 david Exp $

+# Create hostname.if(5) file for wireless device.
+if [ -f /etc/rc.wireless ]; then
+       . /etc/rc.wireless
+fi
+
 # Strip comments (and leading/trailing whitespace if IFS is set)
 # from a file and spew to stdout
 stripcom() {

/etc/rc.wireless:

#!/bin/sh

CONF="/etc/rc.wireless.conf"
IFNAME=`sed -ne 's/IFNAME=\"\(.*\)\"/\1/p' ${CONF}`
HFILE="/etc/hostname.${IFNAME}"
TFILE=`mktemp`
OUTPUT="dhcp NONE NONE NONE "

rm -f ${HFILE}

ifconfig -M ${IFNAME} | sed -ne 's/.*\(..:..:..:..:..:..\).*/\1/p' | \
while read MAC; do

        if [ -r ${CONF} ]; then
                . ${CONF}
        else
                exit 1
        fi

        if [ $? = 0 ]; then

                if [ -n "${NWID}" ]; then
                        OUTPUT="${OUTPUT} nwid ${NWID}"
                fi

                if [ -n "${BSSID}" ]; then
                        OUTPUT="${OUTPUT} bssid ${BSSID}"
                fi

                if [ -n "${NWKEY}" ]; then
                        OUTPUT="${OUTPUT} nwkey ${NWKEY}"
                fi

                echo ${OUTPUT} >> ${TFILE}

                break
        fi

done

if [ -s ${TFILE} ]; then
        cp ${TFILE} ${HFILE}
fi

rm -f ${TFILE}

/etc/rc.wireless.conf:

#!/bin/sh
# wireless configuration

IFNAME="iwi0"

case "${MAC}" in
        00:1a:70:4b:f5:64)
                NWID="Akarsoft"
                NWKEY=""
                ;;
        00:e0:98:f4:55:ab)
                NWID="Karim"
                NWKEY="somekey"
                ;;
        00:0d:3a:2a:83:7d)
                NWID="xythos"
                NWKEY="somekey"
                BSSID="00:0d:3a:2a:83:7d"
                ;;
        00:01:95:6a:40:2b)
                NWID="xythos"
                NWKEY="0xf345ad1293"
                BSSID="00:01:95:6a:40:2b"
                ;;
        00:06:25:92:53:df)
                NWID="Lemny"
                NWKEY="somekey"
                ;;
        *)
                return 1
esac

Don't get me wrong, I don't say that this is perfect but it works for me and thought that others who jump from network to network like I do might enjoy it!