Linux Firewalls, Third Edition

Examples of DNAT, LANs, and Proxies

For the residential and small-business site, destination NAT is probably the most welcome addition to Linux NAT.

Host Forwarding

DNAT provides the host-forwarding capability that, until now, was available only through third-party solutions. For small sites with a single public IP address, DNAT allows incoming connections to local services to be transparently forwarded to a server running in a DMZ. Public services aren't required to run on the firewall machine.

With a single IP address, remote sites send client requests to the firewall machine. The firewall is the only local host that's visible to the Internet. The service (for example, a web or mail server) itself is hosted internally in a private network. ...