ssh remote command execution stuck

M

mitrucs

Hi all,

After a while of intensive googling and configuration tuning, I finally decided to submit my case here.

I'm trying to execute commands remotely from my linux box (OpenSSH_5.3p1) to my freebsd FreeBSD box (OpenSSH_5.8p2_hpn13v11). The strange thing is that it works for some commands and not for others and moreover it depends on args. Basically, I just wanted to execute ls:
Code: 
linux-box:~$ ssh user@freebsd-box ls /some/dir

Then I figured out that, according to the amount of files in the targeted directory, the command was stuck or not.

I ended with this little script to measure the actual amount of maximum data that a command can output without being stuck:
Code: 
linux-box:~$ cat test 
DIR=/home/data/test
rm $DIR/*
COUNT=0
while [  1 ]; do
	ls -rt $DIR
	touch $DIR/$COUNT
	let COUNT=COUNT+1
	echo $COUNT
done

linux-box:~$ ssh user@freebsd-box 'bash -s' < test
1
2
3
.
.
.
160
161
162
163
164
165
166
167
168
169
171
^C
After 171 or so, I have to stop the script because it is stuck.

Curiously, the same script applied from my mac box (OpenSSH_5.2p1) works continuously.

Any idea of what's going on?
 
What happens if you run the script locally?

All ssh(1) does is connect to the remote machine and execute whatever you told it.
 
Locally, it works fine on any box.

It really seems like there is a maximum output for each command launched remotely. It is not limited to ls. Commands with small output works while others just don't.
 
Have you tried the other way around? From the FreeBSD box to the Linux machine. Does that have the same result?
 
The only circumstances where I see that type of behavior is when there's an MTU problem.
 
Yeah, I'm leaning towards a network issue too. Either that or some incompatibility between OpenSSH 5.8 and 5.3.
 
From the FreeBSD box to the Linux machine, there is no problem running the script.

During my research, I found some similar problems but none were solved. As I already lost a lot of time on this, I finally opted to develop my scripts on another box, running MacOS.

I can reproduce the problem from another linux box running OpenSSH_5.5p1. Maybe is it also linked to the fact that the FreeBSD box is accessed via IPv6 only? Bug? Or, as you suggest, some kind of network issue.

BTW, how can I tune the MTU?
 
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