I randomly came across the idea of port knocking not too long ago, and thought it looked pretty useful.
I've read some of the critiques on the concept, but I think they were questioning it more as a security defence for servers. I'm aware that, say I owned a webserver or something, if people did know that I was running xyz services and found nothing on a portscan, they'd know instantly that port knocking was in operation and use whatever cracking tools - resulting in minimal extra security.
However, I don't have a big server, just my quiet workstation way out there that nobody is expecting to be offering any services. Therefore, it would be ideal in concealing whatever services I might be running from any opportunistic port scanners.
The strange thing is that when I looked for any software for linux out there, though there are a huge amount of projects, they almost all died somewhere between 2004 - 2005; I couldn't find a single active project.
(even " http://www.portknocking.org/
" 's most recent release was 2004...)
I avoid installing unmaintained software wherever possible as I have found for all sorts of reasons without variation that it is a bad idea. Especially
for security software.
Do you use port knocking? If so, what program do you use?