topic telnet data loss in Operating System - HP-UX

telnet data loss

Steve H_1 — Tue, 13 Jan 2004 05:53:27 GMT

Hi,

I have a problem on my HP-UX10.20 platform. When a user pastes a 'largish' block of data into a telnet session only a small portion is being received.

I used the following test harness to diagnose the problem:

/tmp/read.sh

#!/bin/ksh
trap "stty echo" 1 0
stty -echo
while true
do
read line
echo "$line"
done

Test Data

0...:....|....:....|....:....|....:....|....:....|....:....|....:....|....:....
|
1...:....|....:....|....:....|....:....|....:....|....:....|....:....|....:....
|
2...:....|....:....|....:....|....:....|....:....|....:....|....:....|....:....
|
3...:....|....:....|....:....|....:....|....:....|....:....|....:....|....:....
|
4...:....|....:....|....:....|....:....|....:....|....:....|....:....|....:....
|
5...:....|....:....|....:....|....:....|....:....|....:....|....:....|....:....
|
6...:....|....:....|....:....|....:....|....:....|....:....|....:....|....:....
|
7...:....|....:....|....:....|....:....|....:....|....:....|....:....|....:....
|
8...:....|....:....|....:....|....:....|....:....|....:....|....:....|....:....
|
9...:....|....:....|....:....|....:....|....:....|....:....|....:....|....:....
|
10...:....|....:....|....:....|....:....|....:....|....:....|....:....|....:....
|

To reproduce, I ran the read.sh script, then pasted 8 of the test data lines to
the server. All 8 were displayed correctly. When I try with 10 lines of test data, only the last 28 chars(or 29 or 30 depending on what CRLF's are being sent) are received.

However, this test works fine on my HP-UX11 & AIX platforms so I was wondering if it is a patch problem with 10.20.

I have made sure any telnet patches that looked suitable are installed PHNE_13413, PHNE_24821, PHNE_24822, PHNE_21872 but I still have the problem.

Any help pointing me in the right direction to resolve this would be much appreciated.

Regards Steve.

Re: telnet data loss

A. Clay Stephenson — Tue, 13 Jan 2004 10:17:45 GMT

I've never seen this problem on 10.20. I suspect what you really have is a speed/duplex mismatch between the UNIX box and its corresponding switch port. Surprisingly, typical telnet applications will work just well enough with a duplex mismatch to seem normal until hi i/o rates occur. Check the settings on BOTH ends and make certain that they are hard set. Next, try some ftp transfers of 10MB files or so and make sure than the transfer rates in both directions are reasonable (~ 50% or so of theoretical maximum).

Re: telnet data loss

Steven E. Protter — Tue, 13 Jan 2004 10:29:35 GMT

This could also be a problem with the telnet client or the clipboard on the windows client.

Investigate A. Clay's idea first, I think its a better one. If nothing is found, try a different telnet client or a pc with a different os.

SEP

Re: telnet data loss

Steve H_1 — Tue, 13 Jan 2004 11:10:17 GMT

Thanks for the replies,

I will investigate for any speed/duplexing issues.

I should have put in my original post that the problem exhibits itself on 3 different telnet clients which is what made me think it's more server based(telnetd)than client side.

Just as an aside, I printed off the telnet conversations between RGTERM and the HPUX 10.20 (which exhibits the problem) and 11.00 (which works ok):

HP-UX 10.20 Telnet Negotiation

<-- IAC DO ENVIRONMENT
--> IAC WONT ENVIRONMENT
<-- IAC DO TERMINAL-TYPE
--> IAC WILL TERMINAL-TYPE
<-- IAC SB TERMINAL-TYPE ARG:1
--> IAC SB TTY-TYPE 0 MENTERM IAC SE
<-- IAC SE
<-- IAC DO TERMINAL-SPEED
--> IAC WILL TERMINAL-SPEED
<-- IAC SB TERMINAL-SPEED ARG:1
--> IAC SB TERMINAL-SPEED 0 19200,19200 IAC SE
<-- IAC SE
<-- IAC WILL ECHO
--> IAC DO ECHO
<-- IAC WILL SUPPRESS-GO-AHEAD
--> IAC DO SUPPRESS-GO-AHEAD
<-- IAC DO NAWS
--> IAC WILL NAWS
--> IAC SB NAWS 80 50 IAC SE
<-- IAC DO FLOW-CONTROL
--> IAC WONT FLOW-CONTROL
<-- IAC DO ECHO
--> IAC WONT ECHO

HP-UX 11.00 Telnet Negotiation

<-- IAC DO ENVIRONMENT
--> IAC WONT ENVIRONMENT
<-- IAC DO TERMINAL-TYPE
--> IAC WILL TERMINAL-TYPE
<-- IAC SB TERMINAL-TYPE ARG:1
--> IAC SB TTY-TYPE 0 MENTERM IAC SE
<-- IAC SE
<-- IAC DO TERMINAL-SPEED
--> IAC WILL TERMINAL-SPEED
<-- IAC SB TERMINAL-SPEED ARG:1
--> IAC SB TERMINAL-SPEED 0 19200,19200 IAC SE
<-- IAC SE
<-- IAC WILL ECHO
--> IAC DO ECHO
<-- IAC WILL SUPPRESS-GO-AHEAD
--> IAC DO SUPPRESS-GO-AHEAD
<-- IAC DO NAWS
--> IAC WILL NAWS
--> IAC SB NAWS 80 50 IAC SE
<-- IAC DO FLOW-CONTROL
--> IAC WONT FLOW-CONTROL
<-- IAC DO ECHO
--> IAC WONT ECHO

Both chats seem identical.

An interesting problem :)

Regards Steve

Re: telnet data loss

Sridhar Bhaskarla — Tue, 13 Jan 2004 12:53:48 GMT

Hi Steve,

What does your 'stty -a" print?.

Make sure your ixon and ixoff are set.

$stty ixon
$stty ixoff

and try.

ixoff and ixon control the input/output queues of the terminal.

-Sri

Re: telnet data loss

Steve H_1 — Wed, 14 Jan 2004 05:34:01 GMT

Thanks Sridhar that sorted it.

I completely overlooked the stty settings and on our 10.20 platform ixon was being set but not ixoff.

I set ixoff and all data copies and pastes perfectly.

Thanks to all who replied.

Regards Steve.