Pulse/docs/TEMPERATURE_MONITORING.md

Temperature Monitoring

Pulse can display real-time CPU and NVMe temperatures directly in your dashboard, giving you instant visibility into your hardware health.

Features

• CPU Package Temperature: Shows the overall CPU temperature when available
• Individual Core Temperatures: Tracks each CPU core
• NVMe Drive Temperatures: Monitors NVMe SSD temperatures (visible in the Storage tab's disk list)
• Color-Coded Display:
  • Green: < 60°C (normal)
  • Yellow: 60-80°C (warm)
  • Red: > 80°C (hot)

How It Works

Secure Architecture (v4.24.0+)

For containerized deployments (LXC/Docker), Pulse uses a secure proxy architecture:

1. pulse-temp-proxy runs on the Proxmox host (outside the container)
2. SSH keys are stored on the host filesystem (/var/lib/pulse-temp-proxy/ssh/)
3. Pulse communicates with the proxy via unix socket
4. The proxy handles all SSH connections to cluster nodes

Benefits:

• SSH keys never enter the container
• Container compromise doesn't expose infrastructure credentials
• Automatically configured during installation
• Transparent to users - no setup changes

Legacy Architecture (Pre-v4.24.0 / Native Installs)

For native (non-containerized) installations, Pulse connects directly via SSH:

1. Pulse uses SSH key authentication (like Ansible, Terraform, etc.)
2. Runs sensors -j command to read hardware temperatures
3. SSH key stored in Pulse's home directory

Important for native installs: Run every setup command as the same user account that executes the Pulse service (typically pulse). The backend reads the SSH key from that user's home directory.

Requirements

1. SSH Key Authentication: Your Pulse server needs SSH key access to nodes (no passwords)
2. lm-sensors Package: Installed on nodes to read hardware sensors
3. Passwordless root SSH (Proxmox clusters only): For proxy architecture, the Proxmox host running Pulse must have passwordless root SSH access to all cluster nodes. This is standard for Proxmox clusters but hardened environments may need to create an alternate service account.

Setup (Automatic)

The auto-setup script (Settings → Nodes → Setup Script) will prompt you to configure SSH access for temperature monitoring:

1. Run the auto-setup script on your Proxmox node
2. When prompted for SSH setup, choose "y"
3. Get your Pulse server's public key:

   # On your Pulse server (run as the user running Pulse)
   cat ~/.ssh/id_rsa.pub
   

4. Paste the public key when prompted
5. The script will:
   • Add the key to /root/.ssh/authorized_keys
   • Install lm-sensors
   • Run sensors-detect --auto

If the node is part of a Proxmox cluster, the script will now detect the other members and offer to configure the same SSH/lm-sensors setup on each of them automatically—confirm when prompted to roll it out cluster-wide.

Setup (Manual)

If you skipped SSH setup during auto-setup, you can configure it manually:

1. Generate SSH Key (on Pulse server)

# Run as the user running Pulse (usually the pulse service account)
ssh-keygen -t rsa -N "" -f ~/.ssh/id_rsa

2. Copy Public Key to Proxmox Nodes

# Get your public key
cat ~/.ssh/id_rsa.pub

# Add it to each Proxmox node
ssh root@your-proxmox-node
mkdir -p /root/.ssh
chmod 700 /root/.ssh
echo "YOUR_PUBLIC_KEY_HERE" >> /root/.ssh/authorized_keys
chmod 600 /root/.ssh/authorized_keys

3. Install lm-sensors (on each Proxmox node)

apt-get update
apt-get install -y lm-sensors
sensors-detect --auto

4. Test SSH Connection

From your Pulse server:

ssh root@your-proxmox-node "sensors -j"

You should see JSON output with temperature data.

How It Works

1. Pulse uses SSH to connect to each node as root
2. Runs sensors -j to get temperature data in JSON format
3. Parses CPU temperatures (coretemp/k10temp)
4. Parses NVMe temperatures (nvme-pci-*)
5. Displays CPU temperatures on the overview dashboard and lists NVMe drive temperatures in the Storage tab's disk table when available

Troubleshooting

No Temperature Data Shown

Check SSH access:

# From Pulse server
ssh root@your-proxmox-node "echo test"

Check lm-sensors:

# On Proxmox node
sensors -j

Check Pulse logs:

journalctl -u pulse -f | grep -i temp

Temperature Shows as Unavailable

• lm-sensors may not be installed
• Node may not have temperature sensors
• SSH key authentication may not be working

ARM Devices (Raspberry Pi, etc.)

ARM devices typically don't have the same sensor interfaces. Temperature monitoring may not work or may show different sensors (like thermal_zone0 instead of coretemp).

Security & Architecture

How Temperature Collection Works

Temperature monitoring uses SSH key authentication - the same trusted method used by automation tools like Ansible, Terraform, and Saltstack for managing infrastructure at scale.

What Happens:

1. Pulse connects to your node via SSH using a key (no passwords)
2. Runs sensors -j to get temperature readings in JSON format
3. Parses the data and displays it in the dashboard
4. Disconnects (entire operation takes <1 second)

Security Design:

• ✅ Key-based authentication - More secure than passwords, industry standard
• ✅ Read-only operation - sensors command only reads hardware data
• ✅ Private key stays on Pulse server - Never transmitted or exposed
• ✅ Public key on nodes - Safe to store, can't be used to gain access
• ✅ Instantly revocable - Remove key from authorized_keys to disable
• ✅ Logged and auditable - All connections logged in /var/log/auth.log

What Pulse Uses SSH For

Pulse reuses the SSH access only for the actions already described in Setup (Automatic) and How It Works: adding the public key during setup (if you opt in) and polling sensors -j each cycle. It does nothing else—no extra commands, file changes, or config edits—and revoking the key stops temperature collection immediately.

This is the same security model used by thousands of organizations for infrastructure automation.

Best Practices

1. Dedicated key: Generate a separate SSH key just for Pulse (recommended)
2. Firewall rules: Optionally restrict SSH to your Pulse server's IP
3. Regular monitoring: Review auth logs if you want extra visibility
4. Secure your Pulse server: Keep it updated and behind proper access controls

Command Restrictions (Default)

Pulse now writes the temperature key with a forced command so the connection can only execute sensors -j. Port/X11/agent forwarding and PTY allocation are all disabled automatically when you opt in through the setup script. Re-running the script upgrades older installs to the restricted entry without touching any of your other SSH keys.

# Example entry in /root/.ssh/authorized_keys installed by Pulse
command="sensors -j",no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty ssh-rsa AAAAB3NzaC1yc2E...

You can still manage the entry manually if you prefer, but no extra steps are required for new installations.

Performance Impact

• Minimal: SSH connection is made once per polling cycle
• Timeout: 5 seconds (non-blocking)
• Falls back gracefully if SSH fails
• No impact if SSH is not configured

Container Security Considerations

✅ Resolved in v4.24.0

Secure Proxy Architecture (Current)

As of v4.24.0, containerized deployments use pulse-temp-proxy which eliminates the security concerns:

• SSH keys stored on host - Not accessible from container
• Unix socket communication - Pulse never touches SSH keys
• Automatic during installation - No manual configuration needed
• Container compromise = No credential exposure - Attacker gains nothing

For new installations: The proxy is installed automatically during LXC setup. No action required.

For existing installations (pre-v4.24.0): Upgrade your deployment to use the proxy:

# On your Proxmox host
curl -fsSL https://raw.githubusercontent.com/rcourtman/Pulse/main/scripts/install-temp-proxy.sh | \
  bash -s -- --ctid <your-pulse-container-id>

Legacy Security Concerns (Pre-v4.24.0)

Older versions stored SSH keys inside the container, creating security risks:

• Compromised container = exposed SSH keys
• Even with forced commands, keys could be extracted
• Required manual hardening (key rotation, IP restrictions, etc.)

Hardening Recommendations (Legacy/Native Installs Only)

1. Key Rotation

Rotate SSH keys periodically (e.g., every 90 days):

# On Pulse server
ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519_new -N ""

# Update all nodes' authorized_keys
# Test connectivity
ssh -i ~/.ssh/id_ed25519_new node "sensors -j"

# Replace old key
mv ~/.ssh/id_ed25519_new ~/.ssh/id_ed25519

2. Secret Mounts (Docker)

Mount SSH keys from secure volumes:

version: '3'
services:
  pulse:
    image: rcourtman/pulse:latest
    volumes:
      - pulse-ssh-keys:/home/pulse/.ssh:ro  # Read-only
      - pulse-data:/data
volumes:
  pulse-ssh-keys:
    driver: local
    driver_opts:
      type: tmpfs  # Memory-only, not persisted
      device: tmpfs

3. Monitoring & Alerts

Enable SSH audit logging on Proxmox nodes:

# Install auditd
apt-get install auditd

# Watch SSH access
auditctl -w /root/.ssh -p wa -k ssh_access

# Monitor for unexpected commands
tail -f /var/log/audit/audit.log | grep ssh

4. IP Restrictions

Limit SSH access to your Pulse server IP in /etc/ssh/sshd_config:

Match User root Address 192.168.1.100
    ForceCommand sensors -j
    PermitOpen none
    AllowAgentForwarding no
    AllowTcpForwarding no

Verifying Proxy Installation

To check if your deployment is using the secure proxy:

# On Proxmox host - check proxy service
systemctl status pulse-temp-proxy

# Check if socket exists
ls -l /var/run/pulse-temp-proxy.sock

# View proxy logs
journalctl -u pulse-temp-proxy -f

In the Pulse container, check the logs at startup:

# Should see: "Temperature proxy detected - using secure host-side bridge"
journalctl -u pulse | grep -i proxy

Disabling Temperature Monitoring

To remove SSH access:

# On each Proxmox node
sed -i '/pulse@/d' /root/.ssh/authorized_keys

# Or remove just the forced command entry
sed -i '/command="sensors -j"/d' /root/.ssh/authorized_keys

Temperature data will stop appearing in the dashboard after the next polling cycle.