All you ever wanted to know about Port Knocking

Recently I have received a few emails from people who wanted a copy of my Cerberus program, which allows people to fire covert icmp packets to execute code on remote hosts that you control. I have used this tool for years to secretly open firewall ports, launch nmap and nessus scans and even to email certain information I need while in the field.

Cerberus is not a publically available tool, and hasn't been updated for Unix in years. I keep thinking about porting it to Windows, but just haven't had the time. Last year I started talking about the tool since these days there are tonnes of port knockers that can do similar things. I even released a slidedeck about it called "Introduction to Cerberus: Port knocking with covert packets to secretly open your firewall" which I have presented at a few security conferences and user groups.

Anyways, as I started asking people how they found out about Cerberus, I was told that information about it was up on portknocking.org. Huh? Never heard of it. So I checked it out this morning. Wow. If you want lots of information on all the different types of port knockers out there, you owe it to yourself to check this out. You may be pleasantly surprised how much depth of information on the topic is indexed there. And sure enough... there are links to my slidedeck and information about Cerberus.

Many thanks to Martin Krzywinski for running such a site, and indexing Cerberus up there. The guy lives and runs this in my backyard and I didn't even know it. Great job.