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.
Has anyone seen this before?
172.31.129.222 host in apps looked like itself when it went to the web interface and it got torn down. It just means that the host got "identity" translated.
You can issue
sh xlate debug | i 172.31.129.222
that will show you the same thing.