Re: [squid-users] Reverse ftp proxy

On Wed, Dec 13, 2006, Reale Marco wrote:
> Hi
>
> I have a question not strectly closely related to squid but I hope that
> someone kindly will reply to me.
> I saw questions about ftp reverse proxy, reverse proxy etc...
> But what exactly is an ftp reverse proxy? What is the difference at tcp
> layer?

An FTP proxy is one which:

* provides an FTP server
* relays requests to a backend FTP server where required
* caches files which are requested by the clients

Squid can do two of three but it doesn't provide FTP services at the present
time. I doubt it'd be hard to write something to do it but I don't think any
of the current squid developers have any spare time to do it.

> Usually I configure a static nat (public ip to dmz ip) in order to
> provide ftp service but if I would to configure a reverse proxy with
> squid is possible?

Not yet.

> 1) Is Squid able to act as reverse ftp proxy?
> 2) What is the difference at tcp layer?

At the TCP layer - Squid would be accepting all FTP requests and speaking
the FTP protocol. Data channels would terminate on the Squid proxy rather than
being NATted through to the client. Squid would then issue its own TCP connections
for control/commands and data requests if/where required.

In the NAT form all that is happening is your firewall/gateway is NATting TCP
sessions for FTP control and data as appropriate.

In the Squid form all the FTP TCP sessions would terminate on the Squid server and the
Squid server would then issue new FTP TCP sessions to the real FTP server.

But as I said, Squid doesn't have this functionality.

Adrian

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