autossh(1)
Automatically restart SSH sessions and tunnels when they drop.
Synopsis
autossh [-V] [-M port[:echo_port]] [-f] [-N] [-n] [-g] [-o ssh_option] [ssh_option] [user@]host [command]Description
autossh starts an SSH session and monitors it, automatically restarting the connection if it drops or becomes unresponsive. It uses SSH keepalive or port monitoring to detect dead connections and seamlessly reconnects without user intervention.
This is essential for long-running tunnels, remote development, and scenarios where network interruptions are common. autossh passes all arguments to ssh after its own options, so any valid SSH command works.
Common options
| Flag | What it does |
|---|---|
-M port[:echo_port] | Port for monitoring; autossh opens a port and connects back to verify the tunnel is alive (default 20000) |
-f | Fork to background after SSH connects successfully (detach from terminal) |
-N | Do not run a remote command; useful for port forwarding and tunnels only |
-g | Allow remote hosts to connect to local forwarded ports (gateway mode) |
-o ssh_option | Pass an option directly to SSH (e.g., -o ConnectTimeout=5) |
-V | Print autossh version and exit |
-n | Detach stdin; prevents reading from the terminal (useful in scripts) |
-p port | Specify SSH port (passed to ssh as -p) |
Examples
Start a persistent SSH tunnel forwarding local port 3306 to a remote MySQL server, monitoring on port 20000, and run in background
autossh -M 20000 -f -N [email protected] -L 3306:localhost:3306Create a persistent SOCKS proxy on port 1080 with keepalive every 30 seconds (disable port monitoring with -M 0)
autossh -M 0 -f -N -o ServerAliveInterval=30 [email protected] -D 1080Maintain multiple port forwards to an internal web server through a bastion host
autossh -M 20001 -f -N -L 8080:internal-server:80 -L 8443:internal-server:443 admin@bastionStart an interactive SSH session with automatic reconnection on connection loss
autossh -M 20000 [email protected]Set up reverse port forwarding with both monitoring disabled and keepalive configured for reliability
autossh -M 0 -f -N -o 'ServerAliveInterval=60' -o 'ServerAliveCountMax=3' user@host -R 8888:localhost:22Continuously tail a remote log file with automatic reconnection if the session drops
autossh -M 20000 -f [email protected] 'tail -f /var/log/app.log'