Squid Proxy - Hiding the proxy
By default, Squid has Forwarded-For
turned on. For more info on what X-Forwarded-For
is, have a gander at the Wikipedia article.
In your situation, you'll want to edit your Squid configuration file to include this line: forwarded_for off
and then restart /etc/init.d/squid restart
(assuming a RPM-based distro).