"we're not using wires anymore" -- IEEE 802.11 security measures:
First try: Wired Equivalent Privacy (WEP)
weak link level encryption - broken; deters naive attackers
Second try: WiFi Protected Access (WPA)
Flexible and complex - better on paper; "constantly improving"; support varies (supported in OpenBSD 4.4 onwards)
MAC address filtering: not really useful, but if you want to, see brconfig
- > you need SSH & SSL
See eg www.kjhole.com for references.