This article will be useful for network and system administrators, but also to the home user who wants to secure a network or a single machine. Netfilter allows users to set up, maintain, and inspect the packet filtering rules in the new 2.4 kernel. This document describes how to do masquerading, transparent proxying, port forwarding, and other forms of Network Address Translations with the 2.4 Linux Kernels. This document describes how to use iptables to filter out bad packets for the 2.4 Linux kernels. This documentation will intend to expose the weaknesses that are often ignored.
Firewalls are better than nothing most of the time.
They provide the only major line of defense for many networks, so please do not remove your firewall unless you have given this some serious thought. OSPF is a link-state routing protocol. Link-state routing protocols take the actual state of the network link into account when creating routing tables and calculating routing decisions. This means that factors like bandwidth and delay can be used when calculating a route's best path, instead of the traditional metric of hop count used by the distance-vector family of routing protocols. This documentation is the first in a series of three articles that will examine Check Point Firewall-1 for Linux.