General Proxy Question

Firstly I must apologise; I have posted something similar in the "general UNIX newbies" forum; but in reterospect I think that it's more appropriate here.

Anyhoo;

I am trying to detect whether people accessing one of my servers are coming via a proxied connection. I must add that this is *not* concerned with caching web-pages or anything of the like. There is a peculiarity of some in-house software that we have that means all http connections must be "real".

The only thing that I can think of is to write a daemon in perl which examines the source port of the incoming packet, checking for 'proxy-like' numbers.

On a slight tangent, are the network facets of perl directly portable to an NT implimentation of the language?

Does anybody have any suggestions? Thankyou in advance...

If it's web-traffic you're watching, you can try using SSL connections, at least for authentication. I don't know the specifics, but I have been on sites that verify where you are coming from by forcing an SSL connection, then switching back to normal HTTP...

I may be mistaken, but it's worth a shot...