PIX IPSEC VPN traffic only goes in one direction (no reply traffic)
I recently had a situation where a pix - pix ipsec tunnel appeared to be set up correctly according to all the examples and discussions on CCO.
The problem i encountered was that packets were being encapsulated, sent down the tunnel and decrypted in one direction.
My remote site had a client that could send ping packets to a server at a HQ site. The server was seeing these pings and the server was replying. My HQ pix could see the reply packets (debug packet inside proto icmp) but it was not encapsulating them. It was as if the HQ pix was dropping the reply ping packets.
It turns out that the routing on the HQ pix had a route for the remote network pointing back inwards to the HQ lan router.
To solve this I changed the routes on the HQ pix similar to this...
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...