Re: Relay over SSH tunnel with Postfix?

["Casey T. Deccio" <casey@deccio.net>]

On Sat, 2006-04-22 at 20:55 +0100, Magnus Therning wrote:
> On Fri, Apr 21, 2006 at 01:58:45PM -0400, Roberto C. Sanchez wrote:
> >You could try `ssh -L 25:localhost:25 you@your.server`
> >
> >Of course, that requires that you be root.  If that will not work, use
> >port 2525 on the first part of the tunnel specification and then
> >configure your MUA to use port 2525 on localhost.
> 
> Yes, I've tried that and it works fine, now I want to automate it.
> Ideally the tunnel would be created on demand, when postfix needs to
> flush its spool. Can I do that?

I'm not familiar with Postfix, but in Exim, you can create a simple
router that does this.  You'll need to set up public-key authentication
for password-less logins to the remote box.  This needs to be somewhere
before the primary router configuration in the exim config:

# ------------------------
ssh_remote:
  debug_print = "R: ssh_remote for $local_part@$domain"
  driver = redirect
  domains = ! +local_domains
        senders = *@mydomain
        pipe_transport = address_pipe
        user = local_user
        data = "| ssh -C -l remote_user  /usr/sbin/sendmail -bm
$local_part@$domain"
  no_more
#-------------------------

The following values need to be replaced with their appropriate values:

mydomain : the real domain (example.com)

local_user : the user on the local machine that will be running the ssh
machine (this is the user whose public key will need to be on the remote
account's ~/.ssh/authorized_keys)

remote_user : the user on the remote machine

The line "senders = *@mydomain" is optional.  It qualifies this router
is used only if the sender address has the domain mydomain.  If you wish
to relay for all senders, then you can comment it out.

Casey