Re: [Exim] relay by IP

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Author: Kevin W. Reed
Date:  
To: exim-users
Subject: Re: [Exim] relay by IP
Michael Johnson said:
> Hi gang
>
> I have a machine running Exim 4.30 over a T1. It works wonderfully.
> Everything is great with that machine. Now, I have an interesting
> need with it, and I'm not exactly sure how to do it, although
> I'm pretty sure it's possible.
>
> I have a machine at a remote location running through a cable
> modem. .... I want to have everyone in the remote location use
> the machine there to send mail, and have that machine go through
> my machine at my location. So...


I have this exact type of setup for my personal stuff.

At home in my office I have a Sun box behind the cable router that has
Exim on it. It connects to my remote server using port 2025.

The DNS of the home system is known via a special set of scripts that do a
uniue secure connection from the home server to the remote server on a
regular interval. If the remote server sees a change in the IP (the DHCP
address changed), it updates the DNS entry that is setup for the home
system and performs a dns zone update. This way, I know what the home
connections IP is by way of a dns entry from anywhere automatically.

The home server uses port 2025 to connect to the remote server because the
ISP blocks regular port 25.

All traffic from the home server is smart hosted to the remote server for
delivering on the Internet. All inbound traffic is directed to the remote
server which forwards it back to the home server for traffic needing to be
delivered there. This means that all Internet smtp traffic is via a
server that is fixed, with all the proper forward and reverse dns and I
don't have to worry about problems with the ISP's IP.

The auto updating dns also makes it possible to then gain access to my
home server from just about anywhere on the Internet if I need to without
having to know what the IP happens to be at any time.

The IP doesn't change often though... about 3 times over the past 2 years.

The home system basically has two entries....

For the router, I replaced the dnslookup router with.

send_to_smart_host:
driver = manualroute
route_list = !+local_domains remote_smart_hosts_dns_entry_or_IP
transport = remote_smtp

and replaced the remote_smtp transport with:

remote_smtp:
driver = smtp
port = 2025

The remote server treats is like any other known server although you can
setup SMTP auth if you really think it is necessary as others have suggested.


--
Kevin W. Reed - TNET Services, Inc.
Unoffical Exim MTA Info Forums - http://exim.got-there.com/forums