Linux Firewalling – Insights and Explainations. Covers basic IPchains firewall building, advanced IPchains firewalling, and linux firewall related insights and recommendations on which traffic to allow.
You can download it from the following link: https://packetstormsecurity.com/files/download/22135/ipchains.txt
Source: https://packetstormsecurity.com/files/22135/ipchains.txt.html