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Thanks in advance for any help.

I'm using Ubuntu 10.04 server, OpenSSH is installed standard via package. I have this running on a dozen other machines in this exact format, and they are virtuals so they are even on the same hardware!

I'm using putty on the windows side for a client. I'm using pub/private key.

So what happens is one of two things:

Right off the bat putty says "network error connection refused". I've had this happen up to around 8 times in a row, but RARELY. All other services on machine are still responding without issue, so I know the machine has network connectivity.

More commonly, it lets you in, and after a while it will just drop connection. Same as above, everything is still function, it just seems to be SSH.

Last night, I left a connection up when I left work, and it stayed up ALL NIGHT. That's the only time I've seen a connection to this server stay as long as it did.

I've updated the OS. My next step is to turn on verbose logging in SSH and see if that brings anything to light. Does anyone have any suggestions on how to debug this, or have you seen this before?

Thanks Everyone!!!!

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Is there any possibility that you have an IP conflict on your network? If you're not running anything like fail2ban that might be locking you out, then based on the denied connection attempt it definitely sounds like another host (which is not running SSH) is coming in and bumping your Ubuntu server off its IP.

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You can just do and check following when error occurred.

Update SSH server. Telnet to port 22 and check connection is accepting. Use nmap to make sure ssh service is running. If its not in the same lan do trace and check the reachability.

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