simulating network attacks

[BDNiner]

Is there software that can simulate network attacks? I don't want to actually attack my network per say but i would like to find some of the vulnerabilities and don't want to pay an outside company to do an audit. I setup a server following this how to from howtoforge.com

http://www.howtoforge.com/intrusion-detection-with-snort-mysql-apache2-on-ubuntu-7.10-updated

but i am just sitting and waiting so i want to hurry the process up.

[Scarath]

Try Back-Track, its a live cd distro made for testing nets

Link (http://www.remote-exploit.org/backtrack.html)
Wiki (http://en.wikipedia.org/wiki/BackTrack)

[BDNiner]

I am downloading the ISO now. This seems like exactly what i was looking for. Thank you.