I first read about this in Bruce Schneier's CRYPTO-GRAM, March 15, 2004. Has anyone else heard/thought about this? /quote Port Knocking Port knocking is a clever new computer security trick. It's a way to configure a system so that only systems who know the "secret knock" can access a certain port. For example, you could build a port-knocking defensive system that would not accept any SSH connections (port 22) unless it detected connection attempts to closed ports 1026, 1027, 1029, 1034, 1026, 1044, and 1035 in that sequence within five seconds, then listened on port 22 for a connection within ten seconds. Otherwise, the system would completely ignore port 22. It's a clever idea, and one that could easily be built into VPN systems and the like. Network administrators could create unique knocks for their networks -- family keys, really -- and only give them to authorized users. It's no substitute for good access control, but it's a nice addition. And it's an addition that's invisible to those who don't know about it. /endquote -- Fred Wright fawright-at-earthlink-dot-net --------------------------------------------------- PLUG-discuss mailing list - PLUG-discuss@lists.plug.phoenix.az.us To subscribe, unsubscribe, or to change you mail settings: http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss