I was wondering if anybody knew of a way to filter network traffic on a
certain port---not just filter it, but actually change it.
For example, we'd like to be able to append an automatic "signature" to all
e-mail that goes out of a machine (in unencrypted form, obviously). I know
we can do this at the mail server level, but for some reason I was asked to
try to implement this on the client side.
Does anybody have any tips or starting points? I imagine this would have to
be some sort of kernel/network extension, but I ...