My FWSM recorded the following event and I have no explanation as to how this is possible.
%FWSM-6-305010: Teardown dynamic translation from apps:172.31.129.222 to web:172.31.129.222 duration 3:00:00
If you read closely, the IP addresses are identical but the connection involved two different interfaces on the firewall.
Here is part of the output from "show ip"
Vlan1128 web 172.31.128.254 255.255.255.0 manual Vlan1129 apps 172.31.129.254 255.255.255.0 manual
How would the firewall even build a connection like this. The IP in question is clearly out the apps interface. Even if that address also showed up out the web interface (which would be a server config error), no connection should be built or torn down by the firewall.
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...