Keep SSH Session Alive – Be on the Right Side of Change

Problem Formulation

I just tried to run AutoGPT on an EC2 instance using SSH from my local Windows machine. But here’s the annoying part: the connection always closes and AutoGPT can only work in small ~10 minute increments. When I return to my machine, I need to SSH into my instance and restart the program.

⚔️ Problem Formulation: Your SSH connection to a remote server works properly at your workplace, but it freezes after 10-15 minutes when connecting from home. You don’t receive any error messages, but you notice zombie login users that need to be killed manually.

Quick and Easy Solution (Client-Side)

To prevent an SSH connection from closing when the client goes silent, you can configure the client to send a keep-alive signal to the server periodically.

Create a configuration file in your home directory at $HOME/.ssh/config, and set its permissions to 600 using chmod 600 ~/.ssh/config after file creation. To send a keep-alive signal every 240 seconds, for example, add the following lines to the configuration file:

Host *
    ServerAliveInterval 240

You can get this done with the following two commands on Linux:

printf '%s\n' 'Host *' '    ServerAliveInterval 240' > ~/.ssh/config
chmod 600 ~/.ssh/config

You can then check the file content using the command cat ~/.ssh/config like so:

Alternative Solution: Server Side

In some cases, you have access to the server’s SSH settings. In that case, add an entry ClientAliveInterval 60 to the file /etc/ssh/sshd_config. I used the Vim editor in the terminal to accomplish this.

Second Alternative Solution

You can also try this command to keep the connection alive, i.e., send a keep alive signal every 60 seconds:

ssh -o "ServerAliveInterval 60" <SERVER_ADDRESS>

# Example with Key Pair on AWS EC2: 
ssh -o ServerAliveInterval=60 -i '.\AWS Key Pair.pem' ec2-user@XX.XX.XX.XX

To enable this on all your sessions, add the following line to your /etc/ssh/ssh_config or ~/.ssh/config:

ServerAliveInterval 60

You can use a similar command to write to the file as shown above or simply use vim /etc/ssh/ssh_config or sudo vim /etc/ssh/ssh_config, hit the i key to insert the line and use the key combination (Hotkey) :wq or :wq! to write to the file, save, and quit Vim.

💡 Resource: A detailed explanation of all these configurations is available at the ssh_config manpage.

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