Re: Transparent Proxying of FTP traffic..

From: Oskar Pearson <>
Date: Tue, 3 Jun 1997 21:22:27 +0200

Steve Ollis writes:
> Greetings,
> I'm trying to settle this question with a colleague, and I'd like a
> definitive answer either way. I believe that it can't be done, but I'm a
> little unsure about whether SQUID can handle this so...

You can masquerade ftp connections under linux by inserting the
module ip_masq_ftp

Squid won't understand the masqueraded connection though. You can
simply configure the masquerader (sp?) to pass the traffic straight through,
though you won't save on the traffic.

> To transparently proxy http, you can setup a Cisco to redirect all port 80
> traffic to a Squid host, that then runs as an Accelerator, and fetches the
> request, caching the results.
> Can the same be done for FTP? FTP consists of port 21 (control) and port 20
> (data).
If you look at the source/change the source for the IP masq option and
route traffic through the linux box it can be done. The limiting factors
are your C knowledge, whether you are willing to use linux as a router and
the amount of time you wish to spend on it.

> 2) HTTP already has a fully qualified URL, or pointer to destination data
> in
> the request. FTP (from a non-browser) does not.
In other words you would have to keep state for each of the connections and
figure out where to pass the traffic back to.

Received on Tue Jun 03 1997 - 12:32:28 MDT

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