Re: [SQU] Transparently Proxy FTP

Thierry Coutelier wrote:
>
> Has CISCO still not released WCCP2 to the public ?

They have released it as a internet draft. See www.wrec.org amongst
other places.

> How much work would it take to add FTP support to SQUID. Maybe adding
> a source route pointing to the squid server ?

Quite a lot. Squid is not a FTP proxy. To add FTP proxying support one
must write a full FTP proxy in Squid, and try to figure out how to
unabigously cache FTP requests.

When the browsers are configured to use Squid as a proxy they use HTTP
to speak with the proxy, and then things are a lot easier.

> Is anyone interested in doing this ? I will help as much I can but I
> will not be able to do it myself.

I have tried a couple of times to deduce caching rules for FTP, but I
always come to the conclusion that there are too much state in the FTP
protocol and FTP server to make it viable. For one thing, the following
sequence is not guarenteed to leave you in the same directory as you
started:

  CWD somedir
  CWD ..

And then there are numerous odd FTP servers which do not use UNIX style
paths at all. Examples of this are DOS and VMS servers.

To make the situation even more interesting there are quite many FTP
servers where PWD is broken, making this command unreliable for finding
out what the current directory actually is. Fortunately, in most cases
the bug is only that PWD reports a different path than you can CWD to in
the FTP connection..

A better approach than to try to tweak Squid to support FTP is probably
to start from a FTP proxy. I know of at least two:
a) ftp-gw from the TIS FWTK (available freely for non-commersial use)
b) The "proxy-suite" from SuSE (GPL license).

None of the two supports caching the last time I looked.

--
Henrik Nordstrom
Squid hacker
--
To unsubscribe, see http://www.squid-cache.org/mailing-lists.html