Rescue SSH (Port 2222)
The rescue SSH daemon provides guaranteed emergency access to MEGATRON even under extreme system load, OOM conditions, or process storms.
Configuration
| Property | Value |
|---|---|
| Port | 2222 |
| Config File | /etc/ssh/sshd_config_rescue |
| Service | sshd-rescue.service (systemd) |
| Nice | -20 (highest CPU priority) |
| OOM Score | -1000 (OOM kill protected) |
| I/O Scheduling | Realtime |
When to Use
Use rescue SSH when:
- Normal SSH (port 22) is unresponsive
- System is under extreme CPU load
- OOM killer is active
- K3s pod storms are consuming resources
- You need guaranteed access for emergency maintenance
Connecting
# From local machine
ssh -p 2222 lucas@megatron
# Using SSH config alias
ssh megatron-rescue
# From Mac Studio via Tailscale
ssh -p 2222 [email protected]
Service Management
# Check rescue SSH status
sudo systemctl status sshd-rescue
# Restart rescue SSH
sudo systemctl restart sshd-rescue
# View rescue SSH config
cat /etc/ssh/sshd_config_rescue
How It Works
The rescue SSH daemon runs as a separate sshd process with elevated scheduling priority:
- Nice -20 ensures it gets CPU time before any normal process
- OOMScoreAdjust=-1000 prevents the OOM killer from targeting it
- Realtime I/O scheduling ensures disk access even under I/O saturation
- Separate port (2222) avoids contention with the primary sshd on port 22