Re: POP3 and Firewall

From: NeoSadist (
Date: 02/24/04

Date: Mon, 23 Feb 2004 22:44:41 -0700

John C. wrote:

> Can somebody please clarify my understanding of the POP3 protocol and
> firewalls?
> In a corporate/university network, the administrators have set
> everything up in such a way that many services, including POP3/SMTP,
> do not work.
> (Correct me if I'm wrong) - When the firewall is setup to not permit
> POP3/SMTP, it is not particularly "targeting" the actual protocol, but
> rather just the ports that they normally run on (e.g. port 25). -- Is
> this correct?

Yes, because people can try to use http, for example, over any port they
want. Same goes for pop3, but it only works if the server AND client are
trying to connect to each other on the same port, usually.

> I'm just wondering if the POP/SMTP servers outside the firewall can be
> altered to operate on a more common port.

You could, in theory, use any port you want, so long as you told your
clients what port to use.

> Any information would be greatly appreciated!
> Thanks,
> John

Deliberation, n.:
        The act of examining one's bread to determine which side it is
buttered on.
                -- Ambrose Bierce, "The Devil's Dictionary"

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