ZDNet's LDP Mirror Linux Network Administrators Guide Prev Chapter 11. If you've already read the firewall and accounting chapters, it probably comes as no surprise that the ipfwadm , ipchains , and iptables commands are used to configure the IP masquerade rules as well.
Masquerade rules are a special class of filtering rule.
You can masquerade only datagrams that are received on one interface that will be routed to another interface. To configure a masquerade rule you construct a rule very similar to a firewall forwarding rule, but with special options that tell the kernel to masquerade the datagram. Let's look at an example. A computing science student at Groucho Marx University has a number of computers at home internetworked onto a small Ethernet-based local area network. She has chosen to use one of the reserved private Internet network addresses for her network.