Re: [squid-users] What can squid filter on?

From: Henrik Nordstrom <>
Date: Sat, 31 Mar 2001 01:13:10 +0200

Joe Viel wrote:
> Does squid only do filtering for HTTP, SMTP , and a few other common protocols, or can any two applications talk TCP over squid?

Yes, no, no, maybe.

Squid is a HTTP proxy, period.

SMTP is not understood

Other protocols is not understood

Some TCP applications can be made to abuse the HTTP proxy to tunnel
non-HTTP traffic over the HTTP proxy, but not without modifications to
the applications, and in most times squid.conf allowing the ports to be
used for CONNECT

well.. there are ofcourse ways to tunnel anything over anything... for
example SSH port forwarding over PPP over HTTP but I can imagine people
have done worse things. The sad fact is that if there is a communication
channel capable of something out and getting something in response then
this channel can be abused for tunneling by some clever person having
access to both sides of the channel.

Henrik Nordstrom
Squid hacker
Received on Fri Mar 30 2001 - 16:26:13 MST

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