WAN to LAN Access: A Simple Guide

TL;DR

Generally, devices on a Wide Area Network (WAN) can’t directly see or connect to devices on a Local Area Network (LAN). You need a router and potentially other security measures like port forwarding or a Virtual Private Network (VPN) to allow this connection. This guide explains how.

Understanding the Networks

Before we start, let’s quickly cover what these networks are:

• LAN: Your home or office network – computers, printers, phones all connected locally.
• WAN: A larger network connecting multiple LANs together (like the internet).

Think of your LAN as a private club and the WAN as the outside world. By default, the club doesn’t let strangers in.

Steps to Allow WAN Access to Your LAN

1. Use a Router: This is the most common way. Routers act as gateways between your LAN and the WAN. They have one public IP address (facing the internet) and many private IP addresses (for devices on your LAN).
2. Static IP Address (Recommended): Assign a static IP address to the device you want to access remotely within your LAN. This prevents its IP address from changing, making it easier to connect to.
   • Log into your router’s configuration page (usually via a web browser – check your router’s manual for the address, often 192.168.1.1 or 192.168.0.1).
   • Find the DHCP settings and reserve an IP address for the device’s MAC address.
3. Port Forwarding: This tells your router to send traffic arriving on a specific port to a specific device on your LAN.
   • In your router’s configuration, find the Port Forwarding section (sometimes called Virtual Servers or NAT).
   • Create a new rule for each service you want to access. You’ll need:
     • Service Name: A descriptive name (e.g., ‘Web Server’).
     • External Port: The port number people will use from the WAN (e.g., 80 for HTTP, 443 for HTTPS). Choose a high-numbered port if possible for security.
     • Internal Port: The port number the service uses on your LAN device (usually the same as External Port).
     • Protocol: TCP or UDP (check what your service needs).
     • Internal IP Address: The static IP address of the LAN device.

   Example for forwarding port 80 to a web server at 192.168.1.10:

   Service Name: Web Server
   External Port: 80
   Internal Port: 80
   Protocol: TCP
   Internal IP Address: 192.168.1.10

4. Firewall Considerations: Ensure your router’s firewall allows traffic on the ports you’ve forwarded.
   • Most routers have a basic firewall enabled by default. Port forwarding usually creates exceptions in the firewall.
   • Be careful not to open unnecessary ports, as this increases security risks.
5. Dynamic DNS (Optional): If your public IP address changes frequently, use a Dynamic DNS service.
   • These services give you a fixed hostname that automatically updates with your current IP address.
   • Configure the DDNS settings in your router.
6. Virtual Private Network (VPN): A more secure option, especially for accessing multiple LAN resources.
   • A VPN creates an encrypted tunnel between your WAN device and your LAN.
   • You’ll need a VPN server running on your LAN (some routers have built-in VPN servers).
   • Configure a VPN client on the WAN device to connect to the server.

Security Considerations

• Strong Passwords: Use strong, unique passwords for your router and all devices on your LAN.
• Keep Firmware Updated: Regularly update your router’s firmware to patch security vulnerabilities.
• Limit Port Forwarding: Only forward the ports you absolutely need.
• Consider a VPN: For sensitive data, use a VPN instead of port forwarding.