Re: [PLUG] What is the best way to create a tunnel or a forward? iptables?

[sean finney <seanius@seanius.net>]

On Mon, 2007-04-09 at 21:44 -0700, Marc Zucchelli wrote:
> I'm hosting a clients email on my server.  Something went wrong with
> their router and it's blocking port 25.  I won't have the time to make
> the long trip up to fix it for them for a while, so I was thinking
> about maybe openning up a higher port on the same server, and just
> tunneling that to port 25, and it will be easy enough for me to walk
> them through changing their outgoing port in their email software.
> What is the best way to pull this off?  This is just a temporary
> solution so I don't lose them!

another alternative would be to avoid the packet rewriting and instead
run your smtp service on both port 25 and a higher port as well.  for
example, my ISP blocks port 25 out to anywhere but their relays.  so, my
smtp server (postfix) is listening on both port 25 and 587, and all my
remote clients connect through the latter.

i don't know about other MTA's, but in postfix to listen on a second
port you just copy the line in master.cf that starts with "smtp", and
duplicate it, replacing smtp with the new port number, and restart
postfix.


	sean

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