Re: pre-connect and smtp ?

["M . Thielker" <balsa t-data com>]

Hi,

On 2001.08.19 19:07 Brian Stafford wrote:
> On 2001.08.19 14:09:52 +0100 christophe barbe wrote:
> > I would like to use a remote smtp server using SSH port forwarding
> > capability.
[...]
> Firstly, functionality such as this belongs in libESMTP, not Balsa. 
> Bear in mind the following - encrypting an SMTP session does not achieve
> security
> or confidentiality of the message.  SMTP is a store and forward protocol. 
[...]

A very specific use of this comes to mind that may make this an option for
some people.
Assuming that there is an SMTP server set up to allow relaying from only
vertain hosts, one of which runs sshd. In that case, ssh could be used as a
username/password authentication mechanism for SMTP. Encryption is not the
point in that case, only the port forwarding as such is relevant in this
setup.

> Since SMTP over a SSH tunnel is an ad-hoc solution, I will not write any
> code
> supporting it.  Since ssmtp is hardly deployed and I can't find a RFC
> describing
> it, I am unlikely to write code to support that either.
[...]

This does not necessarily have to be in libESMTP. One could even start the
port forwarding before Balsa and just specify the forwarded port on
localhost as the SMTP server in Balsa. I agree that no special support for
this borderline case is required in Balsa.

> tunnelling, why
> not set up the tunnel using inetd?   Set up the inetd to respond to
> connections on
> port 587 by executing a shell script which in turn connects the tunnel to
> the remote
> server.  The script presents the SMTP session on its standard input and

That is unfortunately not an option. There is no way to forward an existing
connection, AFAIK. ssh will create a listening port on the local host, port
forwarding will be activated as soon as a program opens a connection to that
socket. There may be ways around this, but it would be unrelaible at best.
Still, ssh can be run before Balsa and stay in the background while Balsa is
used.

Melanie