Argh! (Adelphia, E-mail, iptables, etc.)

[kend at xanoptix.com]

>   I've said it before and I'll say it again: Adelphia's TOS prohibit
> hosting
> services of any kind on their Internet feeds.  They would be completely
> within their rights to block anything you try to host, or cut your feed
> entirely.  You have been warned.

I understand entirely.  And, if I were offering services to anyone except me
and my family, I'd even feel guilty.  As it is, if they shut me down, I'll
cope.  In the meantime, I find it nothing but irksome.  [I'll probably wind
up setting up another single-board computer at work to act as my server, but
I don't want my mail to bounce in the couple week's interim while I scrape
together the money and time to put a new system up.]

>   In the following, I assume the outside machine is 1.2.3.4, your inside
> machine is 3.4.5.6, and the non-standard SMTP listener is on TCP/2525.
> Change as needed.

D'oh!  Upon re-reading my e-mail, that's exactly what I _meant_ to ask. 
*sigh*  Senility sets in early, or somethin'.

>   Do the following on the outside machine:
>
> 	iptables -t nat -A PREROUTING -d 1.2.3.4 -p TCP --dport 25 \
> 		-j DNAT --to-dest 3.4.5.6:2525
>
>   Reconfigure your MTA, *OR* do the following on your Adelphia machine:
>
> 	iptables -t nat -A PREROUTING -d 3.4.5.6 -p TCP --dport 2525
> 		-j DNAT --to-dest 3.4.5.6:25

Looks great!  Thanks for the tip.

-Ken