Hello,

I think this is a very basic problem but not for me. When I do ssh from my laptop (through wlan and wan) to my other computer, the session freezes in some time idling.

I have set to my other computer´ s sshd_config TCPKeepAlive yes and KeepAlive yes, I have also tried them with no. What is this about?

Also the kernel tcp_keepalive_time seems to be ok:

sudo cat /proc/sys/net/ipv4/tcp_keepalive_time
7200.

I appreciate any suggestions, this is really annoying me!

edit:

here´ s a bit more info, when the connection freezes I can still see that it established from netstat in the other computer. Is it possible somehow to try to attach back to this connection? Anyway that wouldnt solve the actual problem but it would be nice to know too.

Check your ifconfig (and iwconfig, if wireless), as well as 'netstat -t -s' statistics to see if you are getting a high error rate when the problem occurs.

I am seeing the exact same thing. I haven't taken much time to debug it yet, as I'm usually in and out with ssh, rarely idle, so it doesn't pop up for me terribly often given my usage pattern.

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Maybe we can compare notes. My setup:

client end: Debian Sarge, ssh version 1:3.8.1p1-8.sarge.4
server end: Debian Sid, openssh version 1:4.2p1-5 (provides ssh-server)

After only a few minutes of idle time it will lock up on me. ipconfig doesn't show any errors (checked per suggestion from macemoneta). Both client and server ends still show an ESTABLISHED connection after the lockup. New ssh connections can be created while the old one is locked up. Killing the window on the client end is the only recovery I've found for the hung client. This does not kill the process on the server end. A manual kill -9 on the connection's sshd process is required to clear the server.

I do NOT see any lockups when this same client connects to a totally different server, in my case a server running Solaris 7 (yeah, I know it's old ... not my machine though) This connection can sit idle for hours without lockup.

One thing that caught my eye when viewing netstat output on the client and server after the connection was locked: The client end was showing the ESTABLISHED connection using tcp while the server end was showing tcp6. I have no idea if this is at all relavent, but it caught my eye and I will try to look into it further to rule this out as a factor.

Hi

My setup is the following
Client end: Suse 10.0 openssh-4.1p1-10.4
Server end: Debian 3.1 ssh 3.8.1p1-8.sarg (OpenSSH)

Today I tried to scp from the suse machine to the debian machine and it gave me this:

Protocol major versions differ: 2 vs. 1
lost connection

So that could cause the freezing too. I think I have to compile the newest ssh for my Debian box and see if that helps. Though, I dont have much time so it could take some time to complish that.

Haertig, if you are less busy than me, please let us know if the installation of the new version helps .

Cheers

Further info:

Using Putty v0.58 ssh client from a Win2000 box to connect to that same Debian SID server above ... no lockups.

Using Putty v0.56 from WinXP ... no lockups either.

On server end, changed sshd ListenAddress from :::: to 0.0.0.0 No difference. Still locked up (when connecting from client on Debian Sarge).

Have you tried with different routers and from different clients? My friend tried with ssh and putty but didnt notice freezing. I heard that in some netgear and linksys routers there is a problem which causes session freezing.

I dont right now have an opportunity to try via different routers but I will keep in touch. I want to solve this very annoying problem.