You should be familar with different kinds of network protocals.
Following specified packet format, analyse whether the packet should go through your firewall.
You probably have a understanding on many important ports. Why you open this port instead of another one.
Definitly, what a wide networking knowledge.
Suggest you work over cisco.
Just represent my own opinion.
[[it] 本帖最后由 onlyonegod 于 2008-6-27 16:52 编辑 [/it]]