Router Security: Protecting Your Network

TL;DR

Yes, cascaded routers can improve your network’s security, but it’s not a foolproof solution. Each router acts as another layer of defence, making it harder for attackers to reach inner machines. However, proper configuration is crucial – simply adding more routers won’t automatically secure everything. Firewalls and strong passwords are essential.

How Cascaded Routers Work

Imagine your network like a castle. A single router is the main gate. An attacker breaching that gate has access to everything inside. Adding another router behind the first creates an inner wall. The attacker now needs to breach two walls.

Steps to Improve Security with Cascaded Routers

1. Router Placement: Connect your main router directly to your internet service provider (ISP). Then, connect a second router to the LAN port of your main router. This creates the cascade.
   • The first router handles external communication and initial security checks.
   • The second router protects machines connected to its network from both the internet and the first router’s network.
2. Firewall Configuration (Router 1 – Internet Facing): This is your primary defence.
   • Enable Firewall: Most routers have a built-in firewall; make sure it’s turned on.
   • Port Forwarding: Only forward ports that are absolutely necessary for services you want to access from the internet (e.g., remote desktop). Avoid forwarding unnecessary ports.

     # Example port forwarding rule (may vary by router) 
     Service Name: Remote Desktop
     Port: 3389
     Internal IP Address: 192.168.1.100
     Protocol: TCP

   • DMZ Avoidance: Never place a machine directly in the Demilitarized Zone (DMZ) unless absolutely required, as this exposes it to direct internet access.
3. Firewall Configuration (Router 2 – Inner Network): This provides an extra layer of protection.
   • Enable Firewall: Again, ensure the firewall is active.
   • Block Unwanted Traffic: Configure rules to block traffic from the first router’s network that isn’t explicitly allowed. This prevents compromised machines on Router 1’s network from directly accessing machines on Router 2’s network.

     # Example firewall rule (may vary by router) 
     Source Network: 192.168.1.0/24
     Destination Network: 192.168.2.0/24
     Action: Deny

   • Internal Port Forwarding: If you need to access machines on Router 2’s network from the internet, forward ports through both routers.
4. Strong Passwords: Change the default passwords for *both* routers immediately.
   • Use strong, unique passwords (at least 12 characters with a mix of letters, numbers and symbols).
   • Enable two-factor authentication (2FA) if available.
5. Disable Remote Management: Unless you specifically need it, disable remote management access on both routers.
   • Remote management can be a security vulnerability.
6. Keep Firmware Updated: Regularly update the firmware on both routers to patch security vulnerabilities.
   • Check your router manufacturer’s website for updates. Many routers have automatic update features.
7. Network Segmentation (Optional): Consider using VLANs or separate subnets on Router 2 to isolate different types of devices (e.g., IoT devices, personal computers).
   • This limits the impact of a compromise if one device is infected.

Limitations

Cascaded routers aren’t perfect:

• Double NAT: Cascading can cause issues with some online games and applications due to Network Address Translation (NAT) conflicts.
• Complexity: Managing two firewalls is more complex than managing one.
• Configuration Errors: Incorrect configuration can negate the security benefits or even create new vulnerabilities.