"fo"s test environment

[mixo <mixo@xxxxxxxxxxxxxxxxxxxx>]

I am currently trying to setup (test) "fos" using "piranha" and
have run into a "problem" : all the machines are behind a
firewall. In fact,  to access port 80 on any machine from within
our network you have to go through a proxy even if you are on
our network . What is supposed to eventually happen
(after testing is complete) is, the 2 machines that  I am testing "fos"
on will be made available to the public.

So how can I setup the machines so that they can check that a services
is running on port 80 so as to stop false "network failures"?