Refer to the following sources for additional information on packet
filtering with iptables.
Red Hat Enterprise Linux Security Guide; Red Hat, Inc. — Contains
a chapter about the role of firewalls within an overall security
strategy as well as strategies for constructing firewall rules.
Red Hat Enterprise Linux System Administration Guide; Red Hat, Inc. — Contains
a chapter about configuring firewalls using
Security Level Configuration Tool.
https://www.netfilter.org/
— The home of the netfilter/iptables project. Contains
assorted information about iptables, including
a FAQ addressing specific problems and various helpful guides by
Rusty Russell, the Linux IP firewall maintainer. The HOWTO
documents on the site cover subjects such as basic networking
concepts, kernel packet filtering, and NAT configurations.
