SSH: configuring keepalive so connections don't drop from inactivity

SSH connections drop due to inactivity when there’s no packet exchange for a period of time. To prevent this, configure keepalive on the server:

sudo vi /etc/ssh/sshd_config

Add or edit the lines:

TCPKeepAlive yes
ClientAliveInterval 30
ClientAliveCountMax 240

• TCPKeepAlive yes → enables keepalive at the TCP level
• ClientAliveInterval 30 → sends a keepalive packet every 30 seconds
• ClientAliveCountMax 240 → waits up to 240 attempts before closing (240 × 30s = 2 hours)

Restart the SSH service to apply:

sudo systemctl restart sshd

Client-side alternative: if you don’t control the server, you can configure keepalive in your ~/.ssh/config:

Host *
    ServerAliveInterval 30
    ServerAliveCountMax 240

Works the same way, but configured from the client side.