This document was originally published in Daemon News on May 21, 2003. Hogan, Doug and Hinton, Bryan. “OpenBSD bridge without IPs using IPF tutorial.” March 2001. URL: http://www.daemonnews.org/200103/ipf_bridge.html . (21 May 2003) See references at the end of https://www.giac.org/paper/gsec/3060/openbsd-invisible-firewall/105092 With OpenBSD and IP Filter, a bridge can be setup that filters incoming traffic. The bridge is not assigned an IP address on either network card. The benefit of this type of firewall is that the sender of an incoming packet is entirely oblivious to the existence of an intermediate bridge. This provides transparency and allows the firewall, which is maintained on the bridge, to securely filter incoming packets and forward them without modification to the internal destination. This guide walks through two typical home network connection setups (ADSL and cable modem) using OpenBSD 2.8. Overview With OpenBSD and IP Filter, a bridge can be setup that filters ...