Re: [exim] Strange SMTP problem, no completed to sender

On 07/08/2020 11:25, Cyborg via Exim-users wrote:
> 91    1.619741    X  83.246.80.144    SMTP    60    C: QUIT
> 92    1.620504    83.246.80.144  X    SMTP    102  S: 221
> {serverhostname} closing connection
> 94    1.669586    X  83.246.80.144    TCP       60    2872 → 25 [FIN,
> ACK] Seq=252 Ack=521 Win=4380 Len=0
> 95    1.669610    83.246.80.144  X    TCP       54    25 → 2872 [ACK]
> Seq=521 Ack=253 Win=64046 Len=0
>
> As this is basically the correct procedure to close a connection, as the
> client (X) sends a FIN,ACK and the server reacts with an ACK. But, the
> clients mta or TCP/IP stack awaits something else (probably the FIN the
> server would send, if it hadn't gotten the FIN,ACK itself).

I think you'll find that the server sent a FIN as part of frame #92.

I'm not too surprised that an IOT stack would not be TCP-standards
confirming, but I'm glad to hear that it was fixed in an update.

Laura, if your scenario matches this then you have bad software
on at least one end. I'd still like to see the logging, in full
not just described in your words, from both systems.
--
Cheers,
Jeremy