Firewalls - books

[PiotreK]

Hello,

I'm searching for books about software firewalls (especially system
firewalls - windows firewall, iptables and comparison between them).
I'm going to write a large project in this subject. Please help if you
have information about some really valuable book.

PiotreK

[vpn_dudel]

I recently bought Guide to Firewalls and VPNs. It's not cheap but very very good.