topic Re: Telnet sessions hanging in Operating System - OpenVMS

Telnet sessions hanging

The Brit — Wed, 25 Feb 2009 21:55:18 GMT

We have just moved our production stuff from Alpha to Itanium (Blades) and the following behaviour is being reported.

If a Laptop user opens up a session while connected to his docking station, and then subsequently undocks, the sessions in the Reflections window receive the normal, "Your 'TELNET' connection has terminated.", but the VMS processes do not go away.
When the user tries to reconnect, his request is turned down because we only allow two sessions per node (for licensing reasons). This then requires intervention by a Sys Admin to cleanup the processes that are hanging out there.

In our case, when the Telnet session disconnects, we want the VMS process to die an immediate death, allowing the user to login again.

Is there not a "tcp" parameter in ipconfig which with take care of this???

Dave.

Re: Telnet sessions hanging

John Gillings — Thu, 26 Feb 2009 00:05:23 GMT

Dave,

Enable virtual terminals so you can reconnect to the same session. This is much nicer than killing the process.

If you really want the process to go away, enable virtual terminals and set TTY_TIMEOUT to a very small value. It's in seconds but I'm not sure if 0 means immediate or forever.

Re: Telnet sessions hanging

Hoff — Thu, 26 Feb 2009 00:18:06 GMT

To answer the direct question, TCP/IP services does have a polling (keepalive) knob, but I'd probably (also) enable virtual terminals on the telnet devices.

Either of the following probably require the telnet server to be restarted, or the host rebooted.

For the former, I'd start with the SET SERVICE TELNET /SOCKET_OPTIONS=KEEPALIVE command.

For the latter (and that's the approach I'd use), see the setup docs in the manual or in the OpenVMS FAQ. This can be enabled "hot." Here's the relevant text extracted from that document:

---

5.42.7 How to enable telnet virtual terminals?

To enable virtual terminal support for telnet and
rlogin devices, add the following logical name
definitions into SYLOGICALS.COM:

$ DEFINE/SYSTEM/EXECUTIVE TCPIP$RLOGIN_VTA TRUE
$ DEFINE/SYSTEM/EXECUTIVE TCPIP$TELNET_VTA TRUE

See SYS$STARTUP:SYLOGICALS.TEMPLATE for details on the
typical contents of SYLOGICALS.COM.

In SYSTARTUP_VMS.COM, ensure that a command similar to
the following is invoked:

$ SYSMAN IO CONNECT VTA0/NOADAPTER/DRIVER=SYS$LOADABLE_IMAGES:SYS$TTDRIVER.EXE

In MODPARAMS.DAT, add the following line or (if already
present) mask the specified hexidecimal value into an
existing TTY_DEFCHAR2, and perform a subsequent AUTOGEN
with an eventual reboot:

TTY_DEFCHAR2 = %X20000

This value is TT2$M_DISCONNECT.

....

Re: Telnet sessions hanging

Wim Van den Wyngaert — Thu, 26 Feb 2009 09:27:48 GMT

I find in the exe file that logicals tcpip$telnet_keepalive, _probetime and _droptime are implemented. You can try these to change the settings to a very low value.

Wim

Re: Telnet sessions hanging

Wim Van den Wyngaert — Thu, 26 Feb 2009 10:41:41 GMT

My remark is only VMS client telnet related.

It seems that reflection doesn't support keepalive settings that it passes to the server. So, you must configure the settings in tcp on VMS (sysconfig).

Wim

Re: Telnet sessions hanging

The Brit — Thu, 20 Aug 2009 12:15:00 GMT

The Virtual Terminals solution is unacceptable locally. So we will educate, and live with it.

thanks for your help.

Dave