Setting up a simple wireless network
The first part is to make sure you have a supported card and check your dmesg output to see that the driver loads and initializes the card properly[1] With a successfully configured card you should see something like
ath0 at pci1 dev 4 function 0 "Atheros AR5212" rev 0x01: irq 11 ath0: AR5212 5.6 phy 4.1 rf5111 1.7 rf2111 2.3, ETSI1W, address 00:0d:88:c8:a7:c4
Next, you need to configure the interface for TCP/IP. On OpenBSD, this means an /etc/hostname.ath0 roughly like this:
up media autoselect mediaopt hostap mode 11b chan 6 nwid unwiredbsd \ nwkey 0x1deadbeef9 inet 10.168.103.1
Note that the configuration is divided over two lines. The first line generates an ifconfig command which sets up the interface with the correct parameters for the physical wireless network, the second command, which gets executed only after the first one completes, sets the IP address. Note that we set the channel explicitly, and we enable a weak WEP encryption by setting the nwkey parameter.
 | From OpenBSD 4.4 onwards, we have WPA, config simplified in OpenBSD 4.9 |
|---|---|
From OpenBSD 4.4 onwards, WPA is available. To handle WPA keys we used wpa-psk, either from the command line to generate a pasteable key: $ wpa-psk unwiredbsd mylongpassphrase 0x7579c38e59faaa3b64bd8372e94f74fe7ae2e4e91af154c956a9bfd0240ac9d0 or directly in your network configuration file. Here is the configuration for a WPA access point, OpenBSD 4.4 style: up media autoselect mediaopt hostap mode 11b chan 6 nwid unwiredbsd \ wpa wpapsk $(wpa-psk unwiredbsd mylongpassphase) In OpenBSD 4.9, the WPA key functionality was merged into ifconfig, and the configuration syntax was simplified. The WPA access point configuration in the OpenBSD 4.9 (and newer) style is: up media autoselect mediaopt hostap mode 11b chan 6 nwid unwiredbsd \ wpakey mylongpassphase and you would need to set up IP addresses and likely DHCP too, of course. |
On FreeBSD you would need to put those lines in your /etc/start_if.ath0, and substitute your interface name for ath0 if required
Then you most likely want to set up dhcpd to serve addresses and other relevant network information to clients. Your clients would need an /etc/hostname.ath0 configuration of
up media autoselect mode 11b chan 6 nwid unwiredbsd nwkey 0x1deadbeef9 dhcp
For a setup with WPA and pre-shared keys corresponding to the access point earlier, you would need something like
up media autoselect mode 11b chan 6 nwid unwiredbsd \ wpa wpapsk $(wpa-psk unwiredbsd mylongpassphase)
instead. Note that the details of setting up WPA for FreeBSD differs somewhat.
and again on FreeBSD, you would need to put those lines in your /etc/start_if.ath0, and substitute your interface name for ath0 here if required.
Assuming your gateway does NAT, you will want to set up NAT for the wireless network as well, by making some small changes to your /etc/pf.conf:
air_if = "ath0"
and
nat on $ext_if from $air_if:network to any -> ($ext_if) static-port
You will need a similar near duplicate line for your ftp-proxy config, and include $air_if in your pass rules.
That's all there is to it. This configuration gives you a functional BSD access point, with at least token security via WEP encryption, or WPA if your setup includes OpenBSD.
A somewhat more thorough treatment of wireless networks, including setup tips for newer FreeBSD configurations, can be found in The Book of PF.