Nematocyst is an active countermeasure for the spamforo trojan. Spamforo makes the infected machines send piles of spam; nematocyst emulates an infected machine, but doesn't send any spam; the intent is to make the trojan network useless by loading it with fake slaveclients.
You should run it as a nonprivileged user; better yet, as a nonprivileged user inside a sandbox.
Nematocyst is written in perl and has been tested on Debian GNU/Linux. It requires wget to operate.
It's copyright 2005 Deekoo L. and released under the GPLv2.