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Raspberry Pi Mesh Network

Building a Batman-adv Mesh Network with Raspberry Pi: A Complete Guide
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Introduction
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Mesh networks are becoming increasingly popular for creating resilient, decentralized networks. In this guide, we’ll explore how to build a Batman-adv mesh network using Raspberry Pi devices. Batman-adv is a powerful Layer 2 mesh networking protocol that automatically discovers nodes and finds optimal routing paths.

What is a Mesh Network?
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A mesh network is a decentralized network topology where each node can communicate directly with other nodes without relying on a central router. Key benefits include:

  • Self-healing: If one node fails, traffic automatically routes through alternative paths
  • Scalable: Easy to add or remove nodes without reconfiguring the entire network
  • Resilient: No single point of failure
  • Distributed: Each node can act as both a sender and a relay

What is Batman-adv?
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Batman-adv (Better Approach To Mobile Adhoc Networking - Advanced) is a Linux kernel module that implements a Layer 2 mesh networking protocol. It’s specifically designed for wireless mesh networks and provides:

  • Automatic topology discovery: Nodes automatically find each other
  • Optimal routing: Uses the best available path between nodes
  • Seamless roaming: Nodes can move without losing connectivity
  • Transparent bridging: Works with existing network protocols

Key Features:
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  • Layer 2 operation: Works at the data link layer
  • Automatic neighbor discovery: No manual configuration needed
  • Multiple routing algorithms: Supports different routing protocols
  • Bridge compatibility: Can bridge with Ethernet networks

Why Use Batman-adv for Raspberry Pi Mesh Networks?
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Batman-adv is particularly well-suited for Raspberry Pi mesh networks because:

  1. Resource efficient: Minimal CPU and memory overhead
  2. Linux native: Built into the Linux kernel
  3. Wireless optimized: Designed for wireless mesh networks
  4. Community support: Active development and documentation
  5. Flexible deployment: Supports various network topologies

Hardware Requirements
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Minimum Requirements per Node:
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  • Raspberry Pi (any model with WiFi)
  • MicroSD card (8GB+)
  • Power supply (5V/3A)
  • WiFi adapter (built-in or USB)

Optional Components:
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  • External antennas for better range
  • PoE hat for power over Ethernet
  • Industrial enclosures for outdoor deployment

Step-by-Step Implementation
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Step 1: Prepare Raspberry Pi OS
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  1. Download and flash Raspberry Pi OS Lite:

    # Download the latest Raspberry Pi OS Lite
wget https://downloads.raspberrypi.org/raspios_lite_armhf/images/

  2. Enable SSH and configure basic settings:

    # Enable SSH
sudo systemctl enable ssh
sudo systemctl start ssh

# Update system
sudo apt update && sudo apt upgrade -y

Step 2: Install Required Packages
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# Install essential packages
sudo apt install -y batctl wireless-tools iw net-tools iproute2

Step 3: Configure Network Interfaces
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  1. Disable conflicting services:

    sudo systemctl stop wpa_supplicant
sudo systemctl disable wpa_supplicant
sudo systemctl stop dhcpcd
sudo systemctl disable dhcpcd
sudo systemctl stop NetworkManager
sudo systemctl disable NetworkManager

  2. Configure wireless interface:

    # Bring down interface
sudo ip link set wlan0 down

# Configure as ad-hoc mode
sudo iwconfig wlan0 mode ad-hoc
sudo iwconfig wlan0 essid "meshnet"
sudo iwconfig wlan0 ap "02:12:34:56:78:9A"
sudo iwconfig wlan0 channel 1

# Bring up interface
sudo ip link set wlan0 up

Step 4: Setup Batman-adv
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# Load batman-adv module
sudo modprobe batman-adv

# Add wireless interface to batman-adv
sudo batctl if add wlan0

# Bring up bat0 interface
sudo ip link set up dev bat0

Step 5: Configure IP Addresses
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For the first node (gateway):

# Assign IP to bat0 interface
sudo ip addr add 192.168.1.1/24 dev bat0

# Enable IP forwarding
echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward

# Configure NAT (if you want internet sharing)
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
sudo iptables -A FORWARD -i bat0 -o eth0 -j ACCEPT
sudo iptables -A FORWARD -i eth0 -o bat0 -m state --state RELATED,ESTABLISHED -j ACCEPT

For additional nodes:

# Assign unique IP to bat0 interface
sudo ip addr add 192.168.1.2/24 dev bat0  # Use different IP for each node

Step 6: Test Connectivity
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# Check batman-adv status
sudo batctl o

# View routing table
sudo batctl r

# Test connectivity between nodes
ping 192.168.1.1  # From node 2 to node 1
ping 192.168.1.2  # From node 1 to node 2

Complete Setup Script
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Here’s a complete setup script that automates the entire process:

#!/bin/bash

# Batman-adv Mesh Network Setup Script

echo "Setting up Batman-adv mesh network..."

# Stop conflicting services
echo "Stopping conflicting services..."
sudo systemctl stop wpa_supplicant 2>/dev/null
sudo systemctl disable wpa_supplicant 2>/dev/null
sudo systemctl stop dhcpcd 2>/dev/null
sudo systemctl disable dhcpcd 2>/dev/null
sudo systemctl stop NetworkManager 2>/dev/null
sudo systemctl disable NetworkManager 2>/dev/null

# Unblock WiFi
echo "Unblocking WiFi..."
sudo rfkill unblock all
sleep 2

# Load batman-adv module
echo "Loading batman-adv module..."
sudo modprobe batman-adv

# Configure wireless interface
echo "Configuring wireless interface..."
sudo ip link set wlan0 down
sudo iwconfig wlan0 mode ad-hoc
sudo iwconfig wlan0 essid "meshnet"
sudo iwconfig wlan0 ap "02:12:34:56:78:9A"
sudo iwconfig wlan0 channel 1
sudo ip link set wlan0 up

# Add wireless interface to batman-adv
echo "Adding wlan0 to batman-adv..."
sudo batctl if add wlan0

# Bring up bat0 interface
echo "Bringing up bat0 interface..."
sudo ip link set up dev bat0

# Configure IP address
echo "Configuring IP address..."
sudo ip addr add 192.168.1.1/24 dev bat0

# Enable IP forwarding
echo "Enabling IP forwarding..."
echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward

# Configure NAT (optional)
echo "Configuring NAT..."
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
sudo iptables -A FORWARD -i bat0 -o eth0 -j ACCEPT
sudo iptables -A FORWARD -i eth0 -o bat0 -m state --state RELATED,ESTABLISHED -j ACCEPT

echo "Mesh network setup complete!"
echo "Check status with: sudo batctl o"

Multi-Node Setup
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Node 1 (Gateway)
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# Run setup script
sudo ./setup_mesh.sh

# This node gets IP 192.168.1.1

Node 2
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# Run setup script but change IP
sudo ./setup_mesh.sh

# Change IP to 192.168.1.2
sudo ip addr del 192.168.1.1/24 dev bat0
sudo ip addr add 192.168.1.2/24 dev bat0

Node 3
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# Run setup script but change IP
sudo ./setup_mesh.sh

# Change IP to 192.168.1.3
sudo ip addr del 192.168.1.1/24 dev bat0
sudo ip addr add 192.168.1.3/24 dev bat0

Verification Commands
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Check Mesh Status
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# View mesh neighbors
sudo batctl o

# View routing table
sudo batctl r

# View interface status
sudo batctl if

# View mesh statistics
sudo batctl s

Test Connectivity
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# Ping between nodes
ping 192.168.1.1
ping 192.168.1.2
ping 192.168.1.3

# Check network interfaces
ip addr show

# Monitor mesh traffic
sudo tcpdump -i bat0

Troubleshooting
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Common Issues
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Nodes not connecting:

  • Verify ESSID and channel match on all nodes
  • Check wireless interface status: iwconfig wlan0
  • Ensure batman-adv module is loaded: lsmod | grep batman

No internet access:

  • Verify iptables rules on gateway node
  • Check IP forwarding: cat /proc/sys/net/ipv4/ip_forward
  • Test internet connectivity: ping 8.8.8.8

High latency:

  • Check signal strength: iwconfig wlan0
  • Monitor network performance: sudo tcpdump -i bat0
  • Check system resources: htop

Debug Commands
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# Check wireless interface status
iwconfig wlan0

# View network interfaces
ip addr show

# Monitor mesh traffic
sudo tcpdump -i bat0

# View batman-adv debug information
sudo batctl if
sudo batctl o
sudo batctl r

Performance Optimization
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Channel Selection
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  • Use channels 1, 6, or 11 to avoid interference
  • Scan for interference: sudo iwlist wlan0 scan | grep -i channel

Transmit Power
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# Set transmit power (if supported)
sudo iwconfig wlan0 txpower 20

Antenna Configuration
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# Check antenna status
iwconfig wlan0

# Configure external antenna if available

Advanced Configuration
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Custom ESSID and Channel
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# Change ESSID
sudo iwconfig wlan0 essid "my_mesh_network"

# Change channel (use 1, 6, or 11 for best performance)
sudo iwconfig wlan0 channel 6

Custom IP Range
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# Use different IP range
sudo ip addr add 10.0.0.1/24 dev bat0

Persistent Configuration
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Create /etc/systemd/system/mesh-network.service:

[Unit]
Description=Batman-adv Mesh Network
After=network.target

[Service]
Type=oneshot
ExecStart=/path/to/setup_mesh.sh
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

Enable the service:

sudo systemctl enable mesh-network.service
sudo systemctl start mesh-network.service

Security Considerations
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  1. Network isolation: Use separate VLANs for different traffic types
  2. Access control: Implement proper authentication mechanisms
  3. Encryption: Consider WPA2/WPA3 for wireless security
  4. Regular updates: Keep system and packages updated

Deployment Best Practices
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  1. Site survey: Analyze RF environment before deployment
  2. Redundancy: Deploy multiple gateway nodes for reliability
  3. Monitoring: Implement network monitoring and alerting
  4. Documentation: Maintain detailed network documentation

Use Cases
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Community Networks
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  • Provide internet access to underserved areas
  • Create resilient community networks
  • Enable local communication during emergencies

IoT Deployments
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  • Connect sensors across large areas
  • Create redundant sensor networks
  • Enable edge computing applications

Disaster Recovery
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  • Rapid network deployment
  • Emergency communication systems
  • Temporary infrastructure replacement

Conclusion
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Batman-adv provides a robust foundation for building mesh networks with Raspberry Pi devices. This implementation offers:

  • Scalability: Easy to add new nodes
  • Reliability: Self-healing network topology
  • Flexibility: Support for various deployment scenarios
  • Cost-effectiveness: Uses affordable Raspberry Pi hardware

The complete implementation is available on GitHub with detailed documentation.

This guide covers the complete implementation of a Batman-adv mesh network using Raspberry Pi devices. For more information, visit the GitHub repository or the Batman-adv project website.

Vivek US
Author
Vivek US
A Tech Enthusiast