Mail delivery wierdness

[keith at smmc.qld.edu.au]

Hi Ryan...

Yep I can confirm it was NOT listening on :25
The techie on the ground swore black & blue it was (always follow what you
know!). I figured it wasn't but maybe it was somethjing I didn't
understand?? He changed the config on exchange and voila! Now I can chat
with smtp on the mail server from outside!
Next question.
Squid is also on the gateway/firewall.
Mail is still not being delivered.
Can I assume if I can chat via telnet to the exchange server : 25 Then
mail can also get thru? Surely that means a persistent session is set up
and mail should also get to it. It isn't being delivered to mailboxes
there so what the???
Any ideas?
Thanks Keith

> keith at smmc.qld.edu.au wrote to Free bsd :
>
>> Hi all,
>> I am trying to connect to an exchange server via my new gateway
>> ipfilter fbsd 4.7 ipnat firewall.
>> Telnetting to the server inside to port 25 reveals...
>>
>> Connected to 203.44.yyy.xx
>> Escape character is ']'.
>> Connection closed by foreign host.
>>
>> Why would it close instantly?
>
> That's usually the behaviour indicating that there is a server at
> 203.44.yyy.xx, but there is no service listening on port 25. (Or, maybe
> your fancy ipfilter firewall is simulating the equivalent).
>
> The first thing you should do is confirm that the server in question
> *is* actually listening on port 25. MS Exchange is pretty far beyond the
> charter of this list, but general network techniques would still apply:
>
> Try the same telnet test using the win32 telnet on the server itself.
> (i.e., telnet localhost:25, and try it by the public IP in case Exchange
> isn't listening on localhost for some reason). If it won't talk SMTP
> with you in either case, you won't get any farther. On the other hand,
> if the test is successful, try the same thing from the next hop (your
> FreeBSD gateway?).
>
> If you isolate the problem to the gateway (and/or every host directly
> connected to the other side of your gateway), you'd probably do well to
> forward your firewall rules and ipnat config to the list (as well as a
> description of what you're trying to accomplish with your config), in
> which case we'll be able to give you better specific instructions.
>
>> Does this reveal while I can't send mail to any email account on it?
>> Is this an exchange hassle? Is port 25 to be only tcp or udp as well.
>
> SMTP is a connection-oriented service.  SMTP can, in theory, be used
> over transport layers other than TCP, but SMTP over UDP would require a
> fair hack to SMTP to implement. So, the short answer is, forget about
> UDP. :-)
>
> - Ryan
>
> --
>   Ryan Thompson <ryan at sasknow.com>
>
>   SaskNow Technologies - http://www.sasknow.com
>   901-1st Avenue North - Saskatoon, SK - S7K 1Y4
>
>         Tel: 306-664-3600   Fax: 306-244-7037   Saskatoon
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>
>
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