Preventing session timeout via ssh/bash/screen/etc

bashdisplayputtysshtimeout

On this particular server, it seems that it's configured somehow to close a session if there is no activity after a few minutes. I'm looking for a good way to prevent it from timing out via my setup of sshing to a primary server using PuTTY for which I have 'sending of null packets to keep session active set to 10 which keeps the session up without issue. I then run gnu screen on the host and ssh out to other machines. It is from these latter machines that I become disconnected. I have tried a few ssh options in my client but I don't think any of them seem to have worked. Whatever mechanism PuTTY uses does seem to work however.

Any ideas are appreciated. I prefer to keep one PuTTY window open than fooling around with multiple windows on my desktop. I'm also not interested in PuTTY Connection Manager either as it is buggy and very slow.

Best Answer

Personally I have my screen session include the local clock in the status bar. That updates once a second, which works as a keep-alive.

My status bar in .screenrc looks like:

hardstatus alwayslastline
hardstatus string '%H %{= mK}%-Lw%{= KW}%50>%n%f* %t%{= mK}%+Lw%< %{= kG}%-=%D %d %M %Y %c:%s%{-}'

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Ubuntu – SSH session becomes unresponsive when logged into Ubuntu Server virtual machine using VirtualBox

OK, so I found the root cause of my issue and it's so simple I'm slightly embarrassed: conflicting network IPs. It was indeed a network issue as I had surmised, however, it was not as complicated as I was making it.

Since I am using bridged networking, the VM shows up in the DHCP clients table along with all the other machines on the network. If any one of those other machines grabs my VM's IP from DHCP (say before I boot my VM up for the day) it will cause a conflict whenever my VM comes on line and might cause my VM to stop responding to SSH. This explains why when I was using the VirtualBox terminal, I did not experience any problems at all.

I'm not exactly sure how most routers handle IP conflicts, but it seems that, whichever machine is last to have network activity gets precedence. So when I bounced the networking on my machine it was fine until whichever machine was sharing the IP decided to engage in networking activity and then BOOM ... my connection would hang.

I reset my VM's static network IP to be quite high in our range, so hopefully that will keep it clear of any IP conflicts with my co-workers' machines.

Windows – PuTTY/SSH: How to Prevent Auto-Logout

When you need only port forwarding, you can try if you disable starting a shell at all, and disable allocating a pseudo-terminal. Then the terminal can no longer be idle. :-)

If your ISP does not allow this, you can run a script like this in your shell session

while sleep 60; do
    echo "Still there"
done

so that the terminal shows activity and it should not be logged out.

But it depends on the operating system they are using which option will help. You did not tell us, did you? uname -a is your friend.

Best Answer

Related Solutions

Ubuntu – SSH session becomes unresponsive when logged into Ubuntu Server virtual machine using VirtualBox

Windows – PuTTY/SSH: How to Prevent Auto-Logout

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