Patent ID: 7191331
Filing Date: 2007-03-13
Classification: H04L

Abstract:
1. A method for network address translation for source address protected packets in a system comprising a plurality of client computers and an address server computer comprising a NAT gateway computer in communication with the client computer the method comprising: one of the client computers requesting a first address from the address server computer, the client computer identifiable to the address server computer by a medium access control number comprising a Medium Access Control address; providing by the address server computer to the client computer a private address in response to the first request; generating an alteration of the medium access control number by the client computer to provide an altered medium access control number wherein a local bit of the Medium Access Control address is flipped; then requesting by the one client computer a second address from the address server, the client computer identifiable by the address server computer by the altered medium access control number; associating by the address server computer the client computer with the first request and the second request by relating the medium access control number with the altered medium access control number; in response to the first and second requests providing by the address server computer to the client computer a public address in response to the second requests, both the first and the second address requests being initiated by the client computer negotiating IPSec Security Association with a remote computer; negotiating a Security Parameter Index (SPI) with a remote station; the NAT gateway computer accessing the SPI from an IPSec-protected packet received from the remote computer; and the NAT gateway computer then negotiating other Security Associations with the remote stations on behalf of other local computers behind the gateway computer.