We have a number of firewalls in place around our organisation and in some cases packets can pass through four levels of firewall limiting the flow TCP traffic.

A concept that I'm used to from software testing is regression testing, allowing you to run a test suite against a changed application to verify that the new changes haven't affected any old features.

Does anyone have any experience or an offer any solutions to being able to perform the same type of thing with firewall changes and network testing? The problem becomes a lot more complicated because you'd ideally want to be originating (and testing receipt) of packets across many machines.