How To Build Your Own Router And Firewall

Building your own router and firewall is an excellent way to customize your network, improve security, and gain more control over your network traffic. It can be done using a combination of hardware and software. Below is a detailed step-by-step guide to building your own router and firewall.

What You'll Need:

Hardware:

1. Old PC or Single-Board Computer (e.g., Raspberry Pi, Intel NUC):

   • An old desktop PC with at least one Ethernet port can work, or you can opt for a more energy-efficient device like a Raspberry Pi or Intel NUC.
   • Ensure the device has at least two network interfaces (e.g., two Ethernet ports) for WAN (internet) and LAN (local network).

2. Ethernet Cables:

   • To connect your router to the internet and your local network.

3. Switch (optional):

   • If you need to connect multiple devices to your LAN network, you may need a network switch.

4. Storage:

   • You’ll need a hard drive or SD card (for Raspberry Pi) to store the operating system and configurations.

Software:

1. Firewall/Router Software:

   • pfSense (most popular and feature-rich open-source firewall/router software)
   • OPNsense (a fork of pfSense, also open-source and highly customizable)
   • IPFire (open-source firewall/router)
   • OpenWRT (a Linux-based firmware for routers, typically used on dedicated devices)

2. Operating System (if not using a dedicated appliance like Raspberry Pi or OpenWRT):

   • FreeBSD (used by pfSense and OPNsense)
   • Linux (used by IPFire or OpenWRT)

Step-by-Step Guide:

Step 1: Prepare the Hardware

1. Select your hardware (old PC, Raspberry Pi, or single-board computer). A basic computer with two network interfaces should suffice.
2. Connect the network interfaces:
   • One network interface will connect to the Internet (WAN) (usually the Ethernet port connected to your modem or ISP).
   • The other network interface will connect to your Local Area Network (LAN), which will distribute the internet to your home devices (wired and wireless).

Step 2: Install the Operating System and Firewall Software

1. Choose your firewall/router software. We'll go with pfSense for this example, but the process is similar for others like OPNsense or IPFire.

   Install pfSense (as an example):

   • Download pfSense:
     1. Go to the pfSense website and download the appropriate version for your hardware (e.g., amd64 for most PCs).
     2. You can download the image for USB installation or a CD/DVD image.
   • Create a bootable USB drive:
     1. Use tools like Rufus (Windows) or dd (Linux/macOS) to create a bootable USB drive from the pfSense image.
   • Boot the PC from the USB drive and start the installation process.
   • Follow the on-screen instructions to install pfSense. It will ask you to select a disk for installation and configure network interfaces (WAN and LAN).

2. Install pfSense (or other software):

   • During installation, you will be prompted to assign the network interfaces (WAN and LAN).
   • Assign WAN to the interface connected to your modem or internet source.
   • Assign LAN to the interface connected to your local network.

Step 3: Configure pfSense/Firewall Software

1. Initial Configuration:

   • After installing the software, connect to the router via web interface using a computer on the LAN side. The default IP address for pfSense is typically 192.168.1.1.
   • Open a browser and type http://192.168.1.1. Login with the default username (admin) and password (pfsense).

2. Set up WAN and LAN interfaces:

   • WAN Interface:
     • This is the interface connected to the internet. In most cases, pfSense will automatically detect and configure the connection.
     • You may need to manually configure the static IP, PPPoE credentials, or DHCP depending on your ISP.
   • LAN Interface:
     • This is the interface connected to your local network. You can assign it a static IP (e.g., 192.168.1.1).
     • The LAN network will distribute internet to your devices.

3. Configure DHCP Server:

   • Enable the DHCP server on the LAN interface to automatically assign IP addresses to devices on your network (e.g., 192.168.1.100 to 192.168.1.200).

Step 4: Set Up Firewall Rules

1. Default Security Rules:
   • WAN-to-LAN: By default, pfSense blocks incoming traffic from the WAN side. Ensure that you have appropriate rules to allow traffic from the LAN side to access the internet.
   • LAN-to-WAN: Ensure that the LAN interface has a rule allowing outbound traffic to the WAN (internet).
2. Advanced Rules (optional):
   • You can add more specific rules for port forwarding, blocking traffic, creating VPNs, or segregating network traffic.
   • For instance, you can block certain websites or set up a VPN for secure access to your network.

Step 5: Secure Your Router/Firewall

1. Change Default Passwords: Change the default login credentials for pfSense or your chosen software to something secure.
2. Enable SSH (Optional): For advanced troubleshooting, you can enable SSH access to your router.
3. Update Software Regularly: Ensure that your router/firewall is updated regularly to avoid security vulnerabilities.

Step 6: Test the Network

1. Check Connection:

   • After configuration, check if devices connected to the LAN network can access the internet.
   • Test WAN (internet) connectivity by trying to ping a website like ping www.google.com from the pfSense console.

2. Test Firewall Rules:

   • Check whether the firewall rules are correctly applied (e.g., try to access blocked websites or services to see if they are properly filtered).

Step 7: Optional Features

1. VPN Setup:
   • Set up a VPN on pfSense for secure remote access to your network, such as OpenVPN or IPSec.
2. Traffic Shaping:
   • Configure Quality of Service (QoS) to prioritize certain types of traffic, like video streaming or gaming.
3. Intrusion Detection/Prevention:
   • You can add features like Snort or Suricata for advanced intrusion detection and prevention.

Advantages of Building Your Own Router/Firewall:

• Customizability: Tailor your network settings to fit your needs.
• Security: You can add advanced security features (VPN, IDS/IPS, VLANs, etc.).
• Cost-Effective: Utilize old hardware or low-cost single-board computers.
• Learning Experience: Gain in-depth knowledge about networking and security.

Conclusion:

Building your own router and firewall with pfSense or similar software is a highly customizable and powerful solution for home or small office networks. By following these steps, you can set up a fully functional router with firewall capabilities, and add features such as VPN, traffic filtering, and more. Enjoy the control and security this solution provides!