TN3270 session disconnected

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TN3270 session disconnected

Hercules390 - General mailing list
If I connect to z/os under Hercules & Windows via a tn3270 client from a remote machine (I tried more than one), after a few minutes of being idle the session is reset.
 This dows not happen for local sessions on the same machine where Hercules is running.
 Is this caused by windows and is there a way to keep the session alive even if idle ?
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RE: TN3270 session disconnected

Hercules390 - General mailing list
You don’t give any versions of software, so which TN3270, which Hercules and which windows might help.

 

I think the converse may be true. That is Hercules is sending Keep-Alive packets which are getting dropped somewhere and the session is then terminated because of this.

 

A quick perusal of the documentation (one version of V4 is here https://hercules-390.github.io/html/hercconf.html)

 

CONKPALV   (idle,intv,count)

Specifies the tn3270 console and telnet clients keepalive option values that control automatic detection of disconnected tn3270/telnet client sessions.

idle  specifies the number of seconds of inactivity until the first keepalive probe is sent (idle time until first probe, or probe frequency).
intv   specifies the interval in seconds between when successive keepalive packets are sent if no acknowledgement is received from the previous one (i.e. the timeout value of the probes themselves).
count  specifies the number of unacknowledged keepalive packets sent before the connection is considered to have failed.

Note: This is a built-in feature of TCP/IP and allows detection of unresponsive TCP/IP connections and not idle clients. That is to say, your connection will not be terminated after 3 seconds of idle time. Your 3270 session can remain idle for many minutes or hours or days without any data being transmitted. If the TCP/IP stack at the other end of the connection -- not your 3270 client itself -- fails to respond to the internal keepalive probe packets however, then it means that the TCP/IP stack itself is down or there has been a physical break in the connection.

Thus, even if your 3270 client is completely idle, your system's TCP/IP stack itself should still respond to the keepalive probes sent by the TCP/IP stack at the Hercules end of the link. If it doesn't, then TCP/IP will terminate the tn3270/telnet session which will cause Hercules to disconnect the terminal.

The three values can also be modified on-demand via the conkpalv panel command, which has the exact same syntax. Note that the syntax is very unforgiving: no spaces are allowed anywhere within the parentheses and each value must be separated from the other with a single comma.

Would have revealed this…

 

Dave

G4UGM

 

From: [hidden email] [mailto:[hidden email]]
Sent: 03 April 2017 11:39
To: [hidden email]
Subject: [hercules-390] TN3270 session disconnected

 






If I connect to z/os under Hercules & Windows via a tn3270 client from a remote machine (I tried more than one), after a few minutes of being idle the session is reset.

This dows not happen for local sessions on the same machine where Hercules is running.

Is this caused by windows and is there a way to keep the session alive even if idle ?








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RE: TN3270 session disconnected

Hercules390 - General mailing list
In reply to this post by Hercules390 - General mailing list
Oh and there were some issues reported with “keep alives” on some builds

 

https://github.com/hercules-390/hyperion/issues/44

 

so it may be worth getting a current snapshot

 

Dave

 

 

From: [hidden email] [mailto:[hidden email]]
Sent: 03 April 2017 11:39
To: [hidden email]
Subject: [hercules-390] TN3270 session disconnected

 






If I connect to z/os under Hercules & Windows via a tn3270 client from a remote machine (I tried more than one), after a few minutes of being idle the session is reset.

This dows not happen for local sessions on the same machine where Hercules is running.

Is this caused by windows and is there a way to keep the session alive even if idle ?








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Re: TN3270 session disconnected

Hercules390 - General mailing list
In reply to this post by Hercules390 - General mailing list
- - - In [hidden email], <ahngb4nond2fjs4iv3chtuacfjmf4dgzileuxli7@...> wrote:
> If I connect to z/os under Hercules & Windows via a tn3270 client from
>a remote machine (I tried more than one), after a few minutes of being
>idle the session is reset.
>This dows not happen for local sessions on the same machine where
>Hercules is running.
>Is this caused by windows and is there a way to keep the session
>alive even if idle ?

What are your TCPIP PROFILE IDLE TIMEOUT and KEEPALIVE interval
set to?
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Re: TN3270 session disconnected

Hercules390 - General mailing list
Running Hercules 3.12 on Windows 10. I tried both QWS3270 and also x3270.
 Tried different values of CONKPALV and it didn't help.
 

 I don't see any TCPIP PROFILE IDLE TIMEOUT and KEEPALIVE values so I guess those
 are set to default. Should I change them?
 

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Re: TN3270 session disconnected

Hercules390 - General mailing list
I found this article in IBM Support:

 http://www-01.ibm.com/support/docview.wss?uid=swg21269806 http://www-01.ibm.com/support/docview.wss?uid=swg21269806

 

 Are TIMEMARK & SCANINTERVAL relevant to my problem?
 

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Re: TN3270 session disconnected

Hercules390 - General mailing list
I shut down the windows Firewall and the sessions keep dropping. So not the Firewall's fault.
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Re: TN3270 session disconnected

Hercules390 - General mailing list
It just occurred to me that I should shut down the firewall on both ends. Once I did that it seems the session stays active. waited 15 min and still good. Is there a way to configure the windows firewall not do reset idle connections ? or should I try
 to lower the SCANINTERVAL and TIMEMARK ?
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Re: TN3270 session disconnected

Hercules390 - General mailing list
On 3 April 2017 at 11:16, [hidden email]
wrote:

> It just occurred to me that I should shut down the firewall on both ends.
> Once I did that it seems the session stays active. waited 15 min and still
> good.


I've had similar problems at work using a VPN/firewall combo. After <a
while> the firewall discards its knowledge of the TCP connection, and then
the next attempt by the z/OS end to send (unsolicited and therefore
unauthorized, in the firewall's opinion) data to the TN3270 client fails.
In my case this was a Checkpoint firewall of some sort, but I don't manage
either that firewall or that z/OS system. It ws fixed (fsvo fixed) long
ago, but still very occasionally recurs.

Tony H.
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Re: TN3270 session disconnected

Hercules390 - General mailing list
The session still gets dropped after 15-20 min when idle. Are there any Windows configuration options that might be causing this to happen?
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Re: TN3270 session disconnected

Hercules390 - General mailing list
1. Please click on the option to include the previous message when replying. I have no idea to which message this is a reply to so no ideas what you have tried.
2. I still have no idea which Hercules and which windows you are talking about.
3. The only thing I can think of is the power management options. Unless you are running on a server windows will go to sleep and power down the network card.

 

Dave

 

From: [hidden email] [mailto:[hidden email]]
Sent: 04 April 2017 07:54
To: [hidden email]
Subject: [hercules-390] Re: TN3270 session disconnected

 



The session still gets dropped after 15-20 min when idle.

Are there any Windows configuration options that might be causing this to happen?








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Re: TN3270 session disconnected

Hercules390 - General mailing list
I thought I provided the following yesterday:

 Running Hercules 3.12 on Windows 10. I tried both QWS3270 and also x3270.
 Tried different values of CONKPALV and it didn't help.

 

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Re: TN3270 session disconnected

Hercules390 - General mailing list
In reply to this post by Hercules390 - General mailing list
Open an issue.  This has a number of advantages:

1.  Those who are not interested can silence the issue.
2.  Context is  immediately available in the browser interface.
3.  You can still append to the issue using the mail interface, if
you're "mark-down challenged".

Please do not clutter the forum with tons of history.

Thanks,

On 04/04/2017 10:38 AM, [hidden email] [hercules-390] wrote:
>
>
>  1. Please click on the option to include the previous message when
>     replying. I have no idea to which message this is a reply to so no
>     ideas what you have tried.
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Re: TN3270 session disconnected

Hercules390 - General mailing list
Open an Issue where ? Never done that before. Sorry for the ignorance.
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Re: TN3270 session disconnected

Hercules390 - General mailing list
On the www.hercules-390.eu website, you will find a link to the SPINHAWK
repository on GitHub.

When you head there, you will find the "Issues" tab.

Joe

On Tue, Apr 4, 2017 at 6:17 AM,
[hidden email] [hercules-390] <
[hidden email]> wrote:

>
>
> Open an Issue where ?
> Never done that before. Sorry for the ignorance.
>
>
>
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Re: TN3270 session disconnected

Hercules390 - General mailing list
In reply to this post by Hercules390 - General mailing list
 - - - In [hidden email], <ahngb4nond2fjs4iv3chtuacfjmf4dgzileuxli7@...> wrote:
> I thought I provided the following yesterday:
> Running Hercules 3.12 on Windows 10. I tried both QWS3270 and
>also x3270.
>Tried different values of CONKPALV and it didn't help.

Are you using QWS3270Plus, QWS3270Secure, or the
really old QWS3270 that was free?
If one of the first two, how did you configure the Keep
Alive options under Session then Connection ?
Interval ?
Use TCPIP ?
Use NOP ?


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Re: TN3270 session disconnected

Hercules390 - General mailing list
In reply to this post by Hercules390 - General mailing list
Is this actually a Hercules issue. Is the IP stack in Hercules, or the IP stack in the guest OS in use?

 

From: [hidden email] [mailto:[hidden email]]
Sent: 04 April 2017 13:20
To: [hidden email]
Subject: Re: [hercules-390] Re: TN3270 session disconnected

 






On the www.hercules-390.eu <http://www.hercules-390.eu>  website, you will find a link to the SPINHAWK repository on GitHub.

 

When you head there, you will find the "Issues" tab.

 

Joe

 

On Tue, Apr 4, 2017 at 6:17 AM, [hidden email] <mailto:[hidden email]>  [hercules-390] <[hidden email] <mailto:[hidden email]> > wrote:

 

Open an Issue where ?

Never done that before. Sorry for the ignorance.

 








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Re: TN3270 session disconnected

Hercules390 - General mailing list
I don't know what component is dropping the session. It only happens when connecting from a remote 3270 emulator client.
 I connected many times from windows to a real remote z/os and never had this issue so probably
 windows is not the culprit.
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Re: TN3270 session disconnected

Hercules390 - General mailing list
Dear ahngb4nond2fjs4iv3chtuacfjmf4dgzileuxli7,

We still don't know if you are connecting to the z/OS Telnet server or
to the hercules 3174 - OSA/IOCC emulation.

That would help a bit Mr ahngb4nond2fjs4iv3chtuacfjmf4dgzileuxli7.

--Ivan


On 4/4/2017 9:59 PM, [hidden email]
[hercules-390] wrote:

>
>
> I don't know what component is dropping the session.
> It only happens when connecting from a remote 3270 emulator client.
> I connected many times from windows to a real remote z/os and never
> had this issue so probably
> windows is not the culprit.
>
>
>



[Non-text portions of this message have been removed]

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Re: TN3270 session disconnected

Hercules390 - General mailing list
In reply to this post by Hercules390 - General mailing list

 If it's the z/OS stack, you should see an LU disconnect message and at the end will be the reason, so if it says TIMEMARK then you know it's the host. Otherwise it likely isn't.

---In [hidden email], <ahngb4nond2fjs4iv3chtuacfjmf4dgzileuxli7@...> wrote :

 I don't know what component is dropping the session. It only happens when connecting from a remote 3270 emulator client.
 I connected many times from windows to a real remote z/os and never had this issue so probably
 windows is not the culprit.


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