OpenWrt Security Hardening: Essential Guide to Block Hackers

D: 🔒 OpenWrt is a powerful open-source router OS, but without proper security measures, it can become a gateway for cyberattacks. This guide covers must-do security practices to protect your network from hackers.

� 1. Change Default Credentials (Username & Password)

The first step to secure OpenWrt is changing the default login credentials.

• Default: root (username) with no password or a weak default one.
• Action:

  # Log in via SSH and set a new password  
  passwd  

• Tip: Use a strong password (mix of letters, numbers, and symbols).

🔑 2. Enable SSH Key Authentication (Disable Password Login)

Brute-force attacks target SSH logins. Key-based authentication is safer.

• Steps:
  1. Generate an SSH key on your computer:

     ssh-keygen -t ed25519  

  2. Copy the public key to OpenWrt:

     ssh-copy-id root@your-router-ip  

  3. Disable password login in /etc/ssh/sshd_config:

     PasswordAuthentication no  

  4. Restart SSH:

     /etc/init.d/sshd restart  

🛡 3. Keep OpenWrt Updated

Outdated firmware = Security vulnerabilities!

• Check for updates:

  opkg update  
  opkg list-upgradable  

• Upgrade packages:

  opkg upgrade   

• Enable automatic updates (optional): Use luci-app-autoupdater.

🔥 4. Configure a Firewall (Restrict Unnecessary Access)

OpenWrt uses firewall4 (nftables) for traffic control.

• Block WAN access to admin panel:
  Go to Luci → Network → Firewall → Traffic Rules → Add:

  Protocol: TCP  
  Source: wan  
  Destination: router IP  
  Destination Port: 80, 443 (HTTP/HTTPS)  
  Action: reject  

• Allow only trusted IPs for remote admin (if needed).

🚫 5. Disable Unused Services (Reduce Attack Surface)

• Turn off Telnet, UPnP, or insecure protocols:

  uci set uhttpd.main.listen_http='0.0.0.0:80'  # Disable HTTP (use HTTPS)  
  uci commit  
  /etc/init.d/uhttpd restart  

• Disable IPv6 if not in use (some ISPs have vulnerabilities).

🕵️ 6. Enable Logging & Intrusion Detection

• Install logread and syslog-ng for monitoring:

  opkg install logread syslog-ng  

• Check logs regularly:

  logread | grep "failed login"  

• Optional: Use Snort or Suricata for deep packet inspection.

🔐 7. Use VPN (WireGuard/OpenVPN) for Secure Remote Access

Instead of exposing SSH/admin to the internet, use a VPN.

• Install WireGuard:

  opkg install wireguard luci-app-wireguard  

• Configure a secure tunnel and connect remotely via VPN only.

🚨 8. MAC Address Filtering (Optional but Effective)

Restrict devices that can connect to your network.

• Go to Luci → Network → Wireless → MAC-Filter → Allow only known devices.

✅ Final Checklist

✔ Changed default credentials
✔ Enabled SSH key authentication
✔ Updated OpenWrt & packages
✔ Configured firewall rules
✔ Disabled unused services
✔ Set up logging/VPN

📌 Pro Tip: Regularly audit your router’s security with tools like Nmap (nmap -sV router-ip).

By following these steps, you’ll drastically reduce the risk of hacking. Stay safe! 🚀

🔗 Need Help? Check OpenWrt’s Security Hardening Wiki.