Build a Raspberry Pi Based DIY Router and Wi-Fi AP

Setting up OpenWrt on a Raspberry Pi allows for a flexible, configurable DIY router or wireless access point. This guide covers installing OpenWrt, configuring LuCI, and adding USB Wi-Fi adapters.

Requirements

• Raspberry Pi: Pi 4 or newer recommended for better performance.
• MicroSD Card: At least 8GB.
• USB Wi-Fi Adapter: Must be compatible with OpenWrt (e.g., Ralink RT5572, MediaTek MT7612U).
• Ethernet Cable: Required for initial setup.
• Power Supply: 5V/3A recommended.

Installing OpenWrt

1. Download OpenWrt: Visit the OpenWrt Firmware Selector and download the correct image for your Raspberry Pi model (e.g., bcm27xx/bcm2711 for Pi 4).
2. Flash the Image to a MicroSD Card:
   • Windows: Use Rufus or Win32 Disk Imager.
   • Mac: Use balenaEtcher.
   • Linux: Run:

     sudo dd if=openwrt-image.img of=/dev/sdX bs=2M conv=fsync
     sync
     

3. Boot OpenWrt: Insert the MicroSD card, connect the Raspberry Pi to your network via Ethernet, and power it on.

Accessing LuCI

1. Connect a computer to the Raspberry Pi via Ethernet.
2. Open a browser and go to http://192.168.1.1.
3. Login with:
   • Username: root
   • No default password (set one immediately).

Configuring OpenWrt

Setting Up Network Interfaces

1. In LuCI, navigate to Network > Interfaces.
2. Configure the LAN interface:
   • Set a static IP if needed.
   • Assign DHCP settings if acting as a router.
3. Save and apply changes.

Enabling Wi-Fi

1. Go to Network > Wireless.
2. If the internal Wi-Fi adapter is listed, enable it. Otherwise, follow the next section to set up a USB adapter.

Adding a USB Wi-Fi Adapter

1. Check for Adapter Recognition:
   • SSH into OpenWrt or use the system log in LuCI.
   • Run lsusb to confirm detection.
2. Install Necessary Drivers (via LuCI):
   • Go to System > Software.
   • Click Update lists.
   • Search for and install drivers based on chipset:
     • Ralink RT5572: Install kmod-rt2800-usb.
     • MediaTek MT7612U: Install kmod-mt76x2u.
3. Configure Wi-Fi:
   • Go to Network > Wireless.
   • Click Add to configure a new Wi-Fi network.
   • Set SSID, encryption (WPA2/WPA3 recommended), and password.
   • Assign the network to LAN or another firewall zone.
4. Save and apply changes.

Final Steps

• Set up a firewall under Network > Firewall.
• Enable remote SSH/Web access under System > Administration.
• If using this setup as a router, configure DHCP and DNS under Network > DHCP and DNS.

Your Raspberry Pi is now a fully functional OpenWrt-powered router.