Keep an SSH Localhost Tunnel Alive on Mac with autossh

Laptop sleep kills SSH. Your “API mysteriously died” is often just a dead tunnel. Here is a minimal keep-alive setup.

Install autossh

brew install autossh

Run a persistent local forward

autossh -M 0 -f -N \
  -o "ServerAliveInterval=30" \
  -o "ServerAliveCountMax=3" \
  -L 3000:127.0.0.1:3000 \
  -L 9223:127.0.0.1:9223 \
  user@vps

Optional: SSH config snippet

Host vps-tunnel
  HostName YOUR_VPS_IP
  User root
  LocalForward 3000 127.0.0.1:3000
  LocalForward 9223 127.0.0.1:9223
  ServerAliveInterval 30
  ServerAliveCountMax 3

Then: autossh -M 0 -f -N vps-tunnel

After wake

If the Mac slept hard, check with lsof -iTCP:3000 -sTCP:LISTEN. No listener → restart autossh.