Firewall as a part of sec life

Dear All
(Here My Idea)

Configuring a firewall is just a chapter of security life of a
system(not just a linux box).

And two latest chapter is

. Optimization (in configuration and/or kernel)
. Testing the security issues(e.g. security assessment tools) . keeping updat2date

So what is your idea about testing a firewall:
1. Configuration to satisfy our needs
2. Keep my things secure
3. Is this firewall, that I'm using, good enough?( in troughput, etc)

Regards
__Radien__