Native IPSec does not allow the traffic to pass through a PAT device. If you have a PIX as a VPN server, then make sure that you run 6.3 on the pix and enable NAT transparency on it to work-around this problem. 3.6 or higher clients support NAT transparency as well
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
[toc:faq]Introduction:This document describes details on how NAT-T
works.Background:ESP encrypts all critical information, encapsulating
the entire inner TCP/UDP datagram within an ESP header. ESP is an IP
protocol in the same sense that TCP and UDP are I...