[Gllug] how to check for a transparent proxy

[Formi]

On Sun, 1 Dec 2002 rich at annexia.org wrote:

> On Sun, Dec 01, 2002 at 03:52:07AM +0000, Pete Ryland wrote:
> > On Sun, Dec 01, 2002 at 03:42:12AM +0000, Xander D Harkness
> wrote:
> > > Does anyone know how to test for a transparent proxy?
> >
> > Go to http://pdr.me.uk/t.php and find the bit that says
> "REMOTE_ADDR" and if
> > that is your IP then there is no proxying, otherwise the
> external IP of your
> > proxy will be there.
>
> A decent transparent proxy will rewrite source addresses, so
> this will NOT tell you if there's a transparent proxy in the
> way.
>
> I'm not actually sure if there is a way to really tell if
> there's
> a transparent proxy between you and another machine (they are,
> after all, supposed to be 'transparent' :-) However if you
> have
> access to another machine on the net which has a known clean
> IP connection, then you can look for telltale evidence such as
> headers added by the proxy to connections.
>
> On the remote (known clean) machine, as root do:
>
> 	nc -l -p 80
>
> >From the local side, do:
>
> 	nc remote 80
>
> Now type:
>
> 	GET / HTTP/1.0
>
> The same should appear almost immediately on the remote side.
>
> Now type:
>
> 	Host: foo
>
> followed by the return key TWICE.
>
> On the remote machine you should just see 'Host: foo'. If
> there
> are any other headers added, then you've got a proxy in the
> middle.
>
> This isn't a foolproof test, but should catch most things.
>
> Rich.
>
>

  Well, if you are running apache somewhere else you just need to
  go to the website, and then check the logs.

  Being on the subject I run squid on my dial-up box, that then
  connects to blueyonder's proxy, never had any problem tough.

  Which I find highly strange.

  At some some point I plan to run a ssh tunnel to a friend's
  server and then out from there, so my squid will be the only
  proxy. That strategy is working beautifully with leafnode.


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