Re: relay access denied

On Fri, 7 Sep 2007, Girish Kulkarni wrote:

GK> So here's a problem:
GK> 1. Suppose there are two well-connected internal networks, A and B. A
GK> has a mail server and B doesn't.
GK> 2. X is a user who has non-root access to all machines on network A
GK> and only one machine, say MAX-B, on network B.
GK> 3. X prefers to keep all his work on machine MAX-B but the mail
GK> server on A doesn't relay mails from any computer on B, in particular
GK> from MAX-B. So X has to keep all his mail related work on some
GK> computer in A (something X doesn't like).

GK> I do not have a clear idea of the issues involved in the solution to
GK> this problem. But I'll be interested in doing some research for that.
GK> Awaiting replies. (A confession, Alan: I am not quite sure if your
GK> post presents a solution to this problem.)
GK>


I've been reading up a bit on ssh tunnels and all the examples seem to
assume that the ssh server and the mail server are the same computer.
But the ssh man page for -L says "Whenever a connection is made to this
port, the connection is forwarded over the secure channel, and a
connection is made to host port hostport from the remote machine"

So it seems to me that

ssh -L 5026:A.mail.server:25 X@MAX_A

should allow you to send your mail to port 5026 on your local MAX_B
computer and it is forwarded via your MAX_A computer to port 25 on the
mail server. Or maybe I have misunderstood.

There appear to be issues about keeping the tunnel from timing out but
there are ways around this, see
http://www.debian-administration.org/articles/487

--
Alan

( If replying by mail, please note that all "sardines" are canned.
However, unless this a very old message, a "tuna" will swim right
through. )

.

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