Traditional IP Network Address Translator (Traditional NAT)

Authors: P. Srisuresh, K. Egevang

Complete Citation

• Srisuresh P.,Egevang, K. 2001. RFC 3022, January 2001

Abstract

Basic Network Address Translation or Basic NAT is a method by which IP addresses are mapped from one group to another, transparent to end users. Network Address Port Translation, or NAPT is a method by which many network addresses and their TCP/UDP (Transmission Control Protocol/User Datagram Protocol) ports are translated into a single network address and its TCP/UDP ports. Together, these two operations, referred to as traditional NAT, provide a mechanism to connect a realm with private addresses to an external realm with globally unique registered addresses.

Annotations

* Purpose: This RFC covers the basics of how Network Address Translation is designed and should be implemented. This method of configuring multiple connections transparently through another connection is of key interest to me, as it is similar to what I am doing when spoofing NIC's.

* This paper covers many aspects of NAT, but of key interest are its methods of handling ports and IP's. In essence, only outgoing connections may be established. Outgoing packets are assigned a new port on the WAN-side based on LAN-side IP and port. Any traffic returning to that port on the WAN is sent back via the port and IP that the creating request(s) originated from.

* My interest in this RFC is that it accomplishes something very similar to what I am doing: the creation of "spoofed" NIC's on a machine. The host machine acts as a gateway, and although it does not currently do any translation, the effect is similar: it provides many network interfaces where there was previously only one.

-- DavidMoore - 1 August 2007