Thought that a few peeps may find this little tool useful....I have had a little look and it seems pretty kool...

The Firewall Tester is a tool designed for testing firewalls filtering policies and Intrusion Detection System (IDS) capabilities.

Features:

- firewall testing
- IDS testing
- simulation of real tcp connections for stateful inspection firewalls (Netfilter,IPfilter...) and IDS (snort)
- connection spoofing
- IP fragmentation / TCP segmentation
- IDS evasion techniques
http://ftester.sourceforge.net/