Suddenly ssh_exchange_identification-Failure

[mbscholz]

Hello everybody,

we sometimes have a strange problem: Some of our servers suddenly don't allow any login (neither via ssh nor via local Terminal nor via Ilo-Console) anymore. Some services seem to crash aswell. When trying to connect via ssh the response is "ssh_exchange_identification: Connection closed by remote host", when trying to connect via Ilo or locally there's simply no response after entering the username. Our only chance is to reboot the server, after that everything works fine, just as before.

We faced this problem on Debian (Etch and Lenny) as well as on RedHat (RHEL5) systems. It happens every few weeks on another machine, so investigating is quite difficult, especially as all logfiles die in the moment of the crash. The machines are of different types, such as DNS or Radius Servers.

Has anybody experienced a similar problem (and an idea of the reasons for it)?

I'm thankful for any help.

Best regards,
Michael

PS: Just to state this out, this is not a problem of hosts.deny/allow as it happens suddenly.

[Jupinder Bedi]

hello ,

There is no need to reboot the server everytime . smiple login from the console and restart the sshd daemon.

Also this problem is due to the old version of ssh . Please apply the latest patch and it will resolve your issue.

Good luck

[Michal Kapalka (mikap)]

hi,

check this link, maybe it will help you :

http://www.linuxquestions.org/questions/linux-software-2/sshexchangeidentification-connection-closed-by-remote-host-103423/

mikap

[mbscholz]

Thanks to you both. Unfortunately there's no way to restart the sshd (as I wrote there's no way to get a terminal, not via ssh nor locally).

The link fits my problem a bit better, but doesn't provide a solution :-(

I'm really curious if somebody else has this problem...and found a solution, of course.

Best regards,
Michael

[Jupinder Bedi]

I faced the same problem on hpux server and I installed the latest recommended patch and finally the server is running fine .

Thats why I told you to install the latest patch of ssh

[mbscholz]

Hmm, alright. Unfortunately our systems are up to date, so this won't help. Fascinatingly this problem occured on the ssh-server of the ilo-Board today. It appears to me as if this was a bug in the ssh-server, in all major versions...

[mbscholz]

An Update to this: It seems to happen after an uptime of 55 or 111 days. Can anybody confirm this? While googling I noticed that this problem seems to be quite widespread whithout solutions...probably some time somebody passes by this entry and can confirm this :)

[Gou_1]

This has been happening to us too. We are running RHEL 4 and like you, it just started happening all of a sudden. I'm starting to suspect a hardware problem. Though, there are no logs.

This guy had a similar problem and he said something about the SCSI card
http://www.unix.com/linux/87930-ssh_-exchange-identification-connection-closed-remote-host.html