cd00r

not listening remote UN*X shell

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cd00r.c is a working proof-of-concept code for a not listening remote shell on UN*X systems.
The idea is the set up a listener in non-promiscuous mode which is looking for a specific sequence of packets arriving on this interface before actually opening any kind of listener. This sequence can be any kind of IP traffic - we use SYN packets in this example - and therefor provides a thick extra layer of obscurity.

++UPDATE++

If you find this interesting, check out http://cmn.listprojects.darklab.org/ for CMN's cool SAdoor project implementing this idea more professional!