Running Home-based mail server, but ISP blocks port 25?

[Rich Payne]

On Mon, 16 Dec 2002, Steven W. Orr wrote:

> On Mon, 16 Dec 2002 pll at lanminds.com wrote:
>
> =>
> =>Hi all,
> =>
> =>Some one was inquiring how they can run a mail server on a port other
> =>than port 25.  They're DNS is hosted by some third party, and their
> =>ISP blocks all ports < 1024 incoming to the cable modem.
> =>
> =>Is there some way to specify a port address in DNS?  How else would
> =>you let the world know your mail server isn't where is should be?
>
> The only thing I can think of is that your nameserver is capable of
> performing some sort of port redirection. e.g., I run with RCN which
> blocks port 80. My nameservice is done via zoneedit.com which provides a
> service to forward to a different port. So I run apache on port 8080 and
> http://www2.syslang.net/ and zoneedit forwards
> http://www.syslang.net/ --> http://www2.syslang.net:8080/
> In the case of RCN, they provide webforwarding but not a generalized port
> forwarding service.
>
> The point is that it has to be done at the nameserver level, since there's
> no way to tell everyone in the world that you're listening on something
> other than port 25.

If your friend could find someone else to do port forwarding that might
work as well. I know with ipchains there was a port forwarding tool. The
only catch would be that the machine doing to port forwarding would be
unable to actually be a mailhost itself.

So, for example, set the MX record of a domain to be mail.domain.com,
which is a machine that has port 25 available, then someone connects to
port 25 on mail.domain.com it forwards the connection to your friends
machine at port X.

An ugly hack at best.... I would think your friend would be better off
getting someone else to handle the mail and pulling it over (fetchmail
etc...) every so often.


--rdp

--
Rich Payne
http://talisman.mv.com
rdp at talisman dot mv dot com