[nos-bbs] SMTP server response to LAN client

[Barry Siegfried]

["(Skip) K8RRA" <k8rra at ameritech.net> wrote]:

> YUP Barry.
>
> On Thu, 2007-10-11 at 18:56 -0400, Barry Siegfried wrote:
>
> > ["(Skip) K8RRA" <k8rra at ameritech.net> wrote]:
> >
> > >snip<
> >
> > like:
> >
> > if(test() == fail) {
> > 	printf("Test 1 has failed!\n");
> > 	usprintf(s,Unknown,Badrecipient);
> > 	break;
> > }
>
> I also considered making seven unknowns (unknown1, unknown2, ...) but
> worried about the consequence or reading such "trashed up messages?" by
> Evolution...

The SMTP client (in this case Evolution) sends commands and the server
replies with numerically designated text messages.  The text inside the
reply lines are immaterial and they can be anything you want them to be.
They are *only* for human consumption on a trace screen.  The client pays
attention *only* to the numbers (not the text).

So you actually could have changed the individual messages which get
sent by the server to the client on the SMTP connection.  The client
(Evolution) wouldn't have cared.  But you would have had to figure out
a way to "observe" the offending one.  From what you said, you did a
packet trace on the 'tun0' interface.  While this works, it is not the
easiest way to see it.

By the way, FYI... FTP and NNTP servers respond to their clients
numerically as well.  Their embedded text messages are irrelevant
from a *programming* perspective.  They only exist to amuse humans...

> I like your approach better...
>
> > >snip<
> >
> > Do you happen to have that NO_SMTP_RELAY (or similar) option
>
> OK - I need to look again.  I missed that "NO_" thought in my first
> five readings... :-(

If my memory serves correctly, that was added to JNOS a long time ago
when people complained about the ease by which their programs could
be turned into open email relays and they couldn't figure out how to
use the rewrite file effectively to bulletproof this behavior.  I
am reasonably certain that the compile time option is to *prevent*
SMTP "relaying" under all circumstances.  In other words, it made
it easy for somebody who didn't understand the mechanics of how
the rewrite file works to turn off *all* SMTP relaying and never
have to worry about it.

Your JNOS SMTP server queueing up email for its client to send is
most certainly a behavior which this compile-time option is designed
to prevent.

> > >snip<
> >
> > Magic?  It's all magic and done with smoke and mirrors.  Didn't you
> > know that?  :)
>
> As a magician I make a better audience member?  And when the mystique
> is all gone I'm left with ??? :-)
>
> THANKS!  I'll make certain to give you feedback on what I find...

I don't personally need any, but if you think the list can benefit
then by all means do so.  :)

73, de Barry, K2MF >>
           o
          <|>      Barry Siegfried
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