Telnet session disconnects abruptly


 
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Operating Systems SCO Telnet session disconnects abruptly
# 1  
Old 08-09-2015
Telnet session disconnects abruptly

I have inherited and SCO OpenServer Release 6 server. The clients connect using telnet to get to a proprietary database application for Service tickets. The issue I am currently having is that the connection just stops abruptly and you can see "telnet session terminated" on the terminal emulation software. The terminal emulation software (Attachmate Relections) has a trace function and I can see an received FD_Close from the server. I have tried a wireshark trace as well and can see several TELNET retransmissions before the disconnect. This has happened with two different terminal emulation programs and on different computers on the network. I have checked /usr/adm/messages and there is nothing relating to the telnet sessions, and I have checked /usr/adm/syslog and I only get the following messages
Code:
service bootpd[2175]: IP address not found: xxx.xxx.xxx.xxx

Where xxx.xxx.xxx.xxx shows the IP address of the computer connecting.

Is there anyway to find out why SCO is disconnecting the sessions. There is no rhyme or reason I can see. It can occur after 1 minute or after 1 hour. If I have two terminal emulator session running on the computer at the same time one session is disconnected and the other keeps running fine for the rest of the day.

I've tried the switch but don't see any errors?

Would anyone have any ideas on why SCO appears to be dropping the connection and where I can look?
Thank you

Last edited by Don Cragun; 08-09-2015 at 12:23 PM.. Reason: Add CODE and ICODE tags.
# 2  
Old 08-09-2015
There are people on this forum who know SCO much better than me as I've not used SCO for years.

However, I do remember that the kernel has "Streams" buffers configured for various network packet sizes and if these buffers are max'd out all hell breaks loose on the network.

I remember you can look at these using the command:

Code:
# crash

and then subcommand:

Code:
 
 strstat

meaning streams statistics.

If these buffers need increasing it involves running ./configure and then relinking the kernel, followed by a reboot to bring that kernel in.

As I say, you will probably get much better answers from others but I hope that helps.
# 3  
Old 08-09-2015
Do you have "keepalive" set on in the terminal emulator?
Does the same thing happen if you switch to ssh?
# 4  
Old 08-10-2015
Thanks hicksd8, I have checked the streams and it appears to be ok

Code:
# crash
dumpfile = /dev/mem, namelist = /stand/unix, outfile = stdout
Engine: 0 of 4  Procslot: 80  Lwpslot: 0  crash
> strstat
ITEM                  INUSE      TOTAL       FAIL
streams                 215     155432          0
queues                 1066     615058          0
message blocks            0     739991          0
message triplets        390    9538784          0
link blocks              26         43          0
stream events             0          0          0

I don't see any fails.

Thank you JGT,
I do not see a keep alive setting in terminal emulation software, but since the disconnect can happen at any time would this be the keep alive? I have seen the same user with an issue leave for lunch for 30 minutes and the session stay up. I have also seen the same user loose connection in the middle of typing on the computer.
I have looked into changing ssh but the proprietary database application for Service tickets does not open when connecting to the ssh session it drops the user into the command prompt and not the application, so I have not been able to connect using ssh for the application.
# 5  
Old 08-10-2015
Several thoughts.
Can you download and install Welcome to April System Design
Pick a version that suits. There is a keep alive setting on the "Config->general settings" window.
How is the user application program started? By setting the shell in etc/passwd, or by 'exec pgm' as the last line of the .profile?
If by the last line of the .profile can you change the .profile so that if the application program dies, the user drops out to a $ prompt instead of being logged off?
# 6  
Old 08-11-2015
Thanks for the reply jgt,
I have downloaded ICE TCP Plus from James River to try a different Terminal emulator. I installed it and will run it on the user's computer having the most trouble.
At this point I am not sure how the program gets started, my apologies but SCO is very new to me I am reading and learning at the same time. I will look this up and get back to you. The problem is when the user drops they lose what they were typing at the time and for some users this could be several lines of a document, so if they are logged off or dropped to the prompt I think they will still lose the information, which is the big problem.
Would you have a link that I can read regarding the .profile and /etc/passwd files and how they work so I can try to figure out how they access the application?
# 7  
Old 08-11-2015
Password file passwd(F)

.profile profile(F)

The entire document library is installed on your local system by default. You can access it by pointing your browser to the SCO host.
Are there any routers/firewalls between the users and the SCO system?
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