Was wondering if anyone out there has run into the same problem I have. I have a PIX firewall that I want to use to connect to the Internet as well as connect via VPN to our ASP. The problem is I am using private addressing in my network so I have to NAT out to the Internet. But now my ASP needs me to perform NAT on the PIX to a different private address so I can connect to them. That wouldn't be a problem, but when I do that I can't get to the Internet b/c I now am NATing to a private address which isn't routable on the Internet. So my question is, is there a way to NAT based on the destination address of a packet? Meaning, when I want to talk to my ASP trigger the VPN and use the Private NAT, but when I want to go anywhere else NAT with the global address that I got from my ISP.
The only way you can NAT based on destination is to use an additional PIX interface. Once you have that you can setup a NAT pool when destined for this additional interface and an Internet NAT pool for the outside interface.
You may be able to accomplish this by using policy based routing. I have used this method to prevent static NAT from occuring when the host is talking to a VPN client. I create a route map that points to an access list to define the source and destination and set the next hop to the same network as a loopback interface. This allows the traffic to pass without NAT even though I have a static translation defined. This may not directly answer your question, but the concepts may help you accomplish your task.
Would your ASP agree if you wouldn't use NAT for traffic between your network and the ASP? This way you can use the NAT 0 command for traffic between your network and the ASP network while all other traffic will be NATed.
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...
Table of Contents 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 an...