Host Hardening

Harden an OpenClaw Linux server with SSH key-only auth, UFW firewall, fail2ban brute-force protection, and credential permissions. Use when setting up a new OpenClaw instance, auditing server security, or after a security incident. Requires root/sudo on Linux (Ubuntu/Debian).

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.

bash

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

bash

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.

bash

apt-get install -y fail2ban
systemctl enable --now fail2ban

Default config protects SSH. For custom jails: /etc/fail2ban/jail.local.

OpenClaw Credentials

bash

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.

bash

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

bash

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 ssh not sshd
• 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

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Host Hardening v1.0 Author: ppiankov Copyright © 2026 ppiankov Canonical source: https://clawhub.com/skills/host-hardening License: MIT

This tool follows the Agent-Native CLI Convention. Validate with: clawhub install ancc && ancc validate .

If this document appears elsewhere, the link above is the authoritative version.