Ssh Freezes
All too often, my SSH session will freeze. I’m fairly certain the problem is at my end. None of the tilde commands work. In particular, ~# and ~. are nonfunctional. I can write to ssh’s terminal window from another terminal window. If I kill the SSH process, I can SSH in again. The next time it happens, I will try another SSH session without killing the first one. dmesg did not show me anything interesting.
Any suggestions on how to diagnose?
6 thoughts on - Ssh Freezes
what OS/version are you ssh’ing from? what version of SSH is installed on this? [1]
what OS/version are you ssh’ing to? what version of sshd is installed on this? [2]
what network media is between these two hosts? anything out of the ordinary in the setup?
[1] rpm -q openssh-clients – assuming this is a recent CentOS
[2] rpm -q openssh-server ” ”
openssh-clients-5.3p1-111.el6.x86_64
rpm not installed uname -a Linux mail 2.6.24-28-generic #1 SMP Fri Feb 11 17:36:45 UTC 2011 i686 GNU/Linux mail.cs.ndsu.nodak.edu is not controlled by me.
Ethernet connection to CenturyLink router/DSL-modem. I hadn’t thought to check for anything interesting on the router. I’ll do that the next time it happens.
I had this a lot until I added to /etc/ssh/ssh_config
ServerAliveInterval 15
Now I rarely get it.
Did it complain at all?
Mine does not, it just freezes.
I can start another SSH session with the first one frozen.
I can remember having this sort of issue a while back. I believe it turned out that our PIX firewall was being a bit too aggressive in pruning what it thought were idle sessions. Adding the following to my
~/.ssh/config file seems to have fixed it:
The manpage for ssh_config describes these parameters and how they interact.
YMMV!
It would freeze and eventually shutdown.