Since this technique requires a IPinIP or GRE tunnel, wouldn't blocking
these two protocols to/from the hosts be sufficient? Assuming of course
the customer's host isn't using that normally.
Chuck
Netco Government Services has recently acquired Multimax and is changing its name to Multimax Inc.
Visit http://www.multimax.com for more information.
Unfortunately, that probably won't work for very long, if at all.
First, it's kinda difficult to guarantee your customers will not use a protocol.
Second, unless you have deep packet inspection, what is to stop the spammer from using, say, port 80 for their tunnel?
Third, what's to stop them from using SSH tunnels?
Etc., etc., etc....
sure, but those are probably just convenience things, what happens when
they setup an ssl tunnel? or http tunnel or ping tunnel?