On 12/20/05, sven.schott / gmail.com <sven.schott / gmail.com> wrote:
> Port knocking is normally TCP and UDP although there are a number of
> implementations with ICMP. It wouldn't be much harder to do with UDP
> but that means that a client would be required as I don't know of
> any(standard) unix programs that can send custom TCP or UDP packets.
> I'm looking at fixing a few of the things in the script like the
> timeout <shudder/> so I might throw in an option for TCP/UDP and a
> small client.

Check out Timeout, part of the standard library.
http://www.ruby-doc.org/stdlib/libdoc/timeout/rdoc/

Also, you can portknock on TCP with any web browser. Just in case that helps. :)