modbender Host Hardening
Secure a Linux server running OpenClaw.
Requirements
- OS: Linux (Ubuntu/Debian — adjust package commands for other distros)
- Privileges: Root or sudo required — this skill modifies system-wide security config
- Pre-check: Verify you have SSH key-based access before disabling password auth
⚠️ All commands below modify system configuration. Confirm with the user before running each section. Do not run these automatically without explicit approval.
SSH — Key-Only Auth
Disables password authentication. Ensure key-based SSH works first or you will be locked out.
sed -i 's/^#*PermitRootLogin.*/PermitRootLogin prohibit-password/' /etc/ssh/sshd_config
sed -i 's/^#*PasswordAuthentication.*/PasswordAuthentication no/' /etc/ssh/sshd_config
systemctl restart ssh
Firewall — Deny All Except SSH
ufw default deny incoming
ufw default allow outgoing
ufw allow ssh
yes | ufw enable
Add more rules as needed (e.g. ufw allow 443 for HTTPS).
Fail2ban — Brute-Force Protection
Installs fail2ban via apt (Debian/Ubuntu). Adjust for other package managers.
apt-get install -y fail2ban
systemctl enable --now fail2ban
Default config protects SSH. For custom jails: /etc/fail2ban/jail.local.
OpenClaw Credentials
chmod 700 ~/.openclaw/credentials
OpenClaw Gateway Service (optional)
Creates a systemd service for auto-restart on reboot. Runs as root — review the service file before enabling.
cat > /etc/systemd/system/openclaw-gateway.service << 'EOF'
[Unit]
Description=OpenClaw Gateway
After=network-online.target
Wants=network-online.target
[Service]
Type=simple
ExecStart=/usr/bin/env openclaw gateway
Restart=always
RestartSec=5
User=root
WorkingDirectory=/root/.openclaw
Environment=HOME=/root
[Install]
WantedBy=multi-user.target
EOF
systemctl daemon-reload && systemctl enable openclaw-gateway
Verify
ufw status # active, SSH allowed
systemctl is-active fail2ban # active
grep PasswordAuthentication /etc/ssh/sshd_config # no
stat -c %a ~/.openclaw/credentials # 700
systemctl is-enabled openclaw-gateway # enabled
Lessons
- On Ubuntu, SSH service is
sshnotsshd - AWS security groups provide network-level filtering but UFW is defense-in-depth
- Always verify key-based SSH access before disabling password auth
- The gateway service is optional — only needed if OpenClaw should survive reboots
Host Hardening v1.0 Author: ppiankov Copyright © 2026 ppiankov Canonical source: https://clawhub.com/skills/host-hardening License: MIT
If this document appears elsewhere, the link above is the authoritative version.