There are additional diagnostic codes available with telnet.  SSH can also
produce more diagnostic with -v or -vv.  But with both of them
disconnecting, the VPN config is looking pretty good as a culprit.  Most
VPN clients have the ability to enable tracing / logging.  Even the Cisco
client that downloads, has a settings config.

Rob Schramm

On Mon, May 9, 2016, 7:41 AM Robin Atwood <[email protected]> wrote:

> Is the ServerAlive parameter set in the SSH server or PuTTY? It should be
> > 0, otherwise you get inactivity timeouts.
>
> Robin
>
> -----Original Message-----
> From: IBM Mainframe Discussion List [mailto:[email protected]] On
> Behalf Of Sean Gleann
> Sent: 09 May 2016 17:07
> To: [email protected]
> Subject: Connectivity problem...
>
> A wide-open subject line, but networking is not my strong point,
> unfortunately.
>
> I'm looking for some help regarding an intermittent communication failure
> on our z/OS 1.13 system.
>
> We use PuTTY to create a tunnelled connection to TN3270, and PCOMM to
> provide the 3270 emulation.
> When using, say, TSO, on the PCOMM panel, everything appears to be going
> well, until it simply... dies.
> I get to the point of hitting ENTER or PFnn for whatever reason, and I am
> presented  with a the 'X clock' symbols in the status area, followed by a
> disconnect some short while (< 1  minute) later.
>
> At the time of that disconnect, the PuTTY connection fails also (which
> would be the reason for the PCOMM failure). PuTTY throws up a message box
> saying "Network error: Software caused connection abort" which means
> precisely nothing to me.
> From there, it is possible to use PuTTY's 'Restart Session' option, and
> then PCOMM's 'Connect' option to get things moving again, until the time of
> the next failure.
>
> There's nothing showing up on the SYSLOG, and I can't think of anywhere
> else I might look for more/better info.
> There doesn't seem to be any pattern to the failure events in terms of
> time-of-day or system loading. It just ... stops.
>
> For what it's worth, z/OS system is hosted by the Dallas Innovation
> Center, and we've recently tried to put the system on a VPN - which is when
> all this trouble started.
> I'm trying to get SNMP working in the hope that I can get more info, but
> *that* is probably going to be the subject of an upcoming thread...
>
> Can anyone point me in the direction of further diagnostics at all, please?
> Any help would be much appreciated.
>
> Sean
>
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-- 

Rob Schramm
The Art of Mainframe, Inc

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