A Practical Guide

Created by Suriyadeepan and Selva Kumar




  • Better Approach To Mobile Adhoc Network

  • Implemented as a linux kernel module

  • Operates on layer 2 of network stack


  • All the packets are encapsulated and routed by batman-adv

  • All the participating nodes appear to be link-local


  • Supports anything on top of layer 2 : IPV4, IPV6, DHCP, IPX

  • Nodes can participate in a mesh without having an IP

  • Easy integration of non-mesh clients (think Android)


  • A tool to configure and debug the batman-adv kernel module

  • Interface to settings and status information of batman-adv

  • Provides a layer-2 version of ping, traceroute and tcpdump(MAC)


  • Add and remove interfaces to the mesh network

  • Set or change parameters of batman-adv module

  • Enable or disable features of batman-adv


  • Get the list of mesh nodes and non-mesh nodes in the network

  • Log messages from batman-adv

  • List of available gateways


Compatibility Check

Before compiling batman-adv or batctl find the versions compatible with your kernel.

Kernel Version

					uname -r # 3.19.0-25-generic

Find compatible versions

From here


Download batclt and batman-adv

Compile batman-adv

# compile
make -j4
# find module
ls *.ko
# insert module
sudo insmod batman-adv.ko
# check version
batctl -v

Compile batctl

# compile
make -j4
# install
sudo make install
# check version
batctl -v

Quick Node setup

Add Interface

Which interface to add to batman-adv to build the mesh network?

# Add an interface wlan0/eth0
batctl if add wlan0
# check interface
batctl if

bat0 : Virtual Interface

Any packet that enters this interface will be examined by the batman-adv for its destination mac-adress and will be forwarded.

Simple Mesh Network

# kill network manager
sudo service network-manager stop
# load the module up
modprobe batman-adv
# setup network interfaces
ip link set up dev eth0
# set mtu compatible with batman
ip link set mtu 1532 dev wlan0
# configure the wlan interface to operate with mtus of 1532
#		(batman requires it) and turn enc off 
iwconfig wlan0 mode ad-hoc channel 6 essid PYMESH ap 02:12:34:56:78:9A enc off
# add wlan0 to the batman-adv virtual interface
# 	(so it can communicate with other batman-adv nodes)
batctl if add wlan0
# bringing up wireless ad-hoc interface
ifconfig wlan0 up
# bringing up bat0 interface
ifconfig bat0 up

How to kill BATMAN?

# disable kernel module
rmmod batman-adv
# restart network manager
service network-manager restart


Need to bridge Adhoc and Infrastructure APs

To let non-mesh nodes (think Android) connect to the network

Setup Bridge Interface

ip link add name mesh-bridge type bridge
ip link set dev eth0 master mesh-bridge
ip link set dev bat0 master mesh-bridge
ip link set up dev eth0
ip link set up dev bat0
ip link set up dev mesh-bridge


Compatibility Check

Table of Hardware

Compiled Packages

Flashing your Router

Get our compiled firmware here

LUCI Interface


IP Allocation. How?

  1. Static IP
    Manually setting a static IP address

  2. DHCP
    OpenWrt comes with DHCP server

Configuring DHCP

  • Go to /etc/config/dhcp
  • start : start address
  • limit : number of devices to serve


config dhcp 'lan'
      option interface 'lan'
      option start '100'
      option limit '100'
      option leasetime '12h'


config interface 'lan'
    option ipaddr ''
    option netmask ''

What is DNS?

  • Domain Name Server

  • Human readable names for services

How does it work?

  1. The browser talks to the DNS server, asks for name resolution

  2. DNS maintains the mapping between name to IP address

  3. DNS server looks in its map and reponds with the IP address

How do we do it?

OpenWRT comes with a DNS utility called Dnsmasq.

It can be configured through the LUCI interface.

Dnsmasq Configuration

  1. Find the IP address allocated to your laptop; say

  2. To add a mapping entry, log in to the router, via ssh

  3. Create a new file under directory /etc/, "hosts.pymesh"

  4. add the following line to the file pymesh.p2p

Dnsmasq Configuration

  1. Log into the router, via browser

  2. Go to DHCP and DNS configuration page, In the top menu click Network -> DHCP and DNS.

  3. In the Additional Hosts Files field(highlighted in the figure below) add the name of the file which we have created above.

  4. Click Save & Apply

Dnsmasq Configuration

P2P Apps

Use Cases

  • Chat

  • Voice Call

  • Social Networking

  • Micro-blogging

  • File Sharing

  • Personal Website : Portfolio

  • Knowledge sharing

Serval Project

Communications should not just be for the geographically, financially otherwise fortunate — for it is the unfortunate who need it most.

Serval Project

  1. Communicate anytime

  2. Communicate anywhere

  3. Communicate privately

  4. Communicate with people

Batphone for Android



  • Decentralized and delay-tolerant twitter-like mobile application

  • Enables the spread of messages in an epidemic fashion using automatically formed and opportunistic local ad-hoc network

  • Every message sent or received with are stored on the local database and pushed to every other device it meets

  • Messages naturally propagates throughout the network using social links as the underlying infrastructure

Briar Project

Typical messaging software relies on central servers and exposes messages and relationships to surveillance Direct, encrypted connections between users to prevent surveillance and censorship

Briar Project

  • Peer-to-peer encrypted messaging and forums

  • Messages are stored securely on your device, not in the cloud

  • Connect directly with nearby contacts - no Internet access required

  • Free and open source software

  • Designed for activists, journalists, and anyone else who needs a safe, easy and robust way to communicate

Open Tracker

opentracker is a open and free bittorrent tracker project.

It aims for minimal resource usage and is intended to run at your wlan router.

Open Tracker

A torrent tracker basically is an http-Server that collects all clients ip addresses into pools sorted by one of the request strings parameters and answers all other clients that specified this exact same parameter a list of all other recent clients.

OpenTracker for OpenWrt

Knowledge Sharing


  • An Offline web browser to browse wikipedia content
  • Serves offline content from dump files called zim files

Zim Files

Download Kiwix

Download Kiwix from here.

Launch Kiwix

Run the executable file named kiwix.

Open Zim File

Choose Zim File

Browse Offline Content

Serve Local Content

Libre Digital Library

Karai GLUG, Alagappa University
Inspired by Puducherry Community WiFi Initiative(pymesh), we would like to kick start the mesh network in Karaikudi too.

Zero Conf


In the current model of Internet, or any large network, both providing a service and connecting to a service are unnecessarily complicated.

To make a service visible, one needs to register a name as proxy to the service (IP + PORT).

To find a needed service, one needs support from a centralized DNS server.

This is where zeroconf comes in.

Pillars of Zero Conf

A set of technologies that automatically creates a usable computer network

Three Pillars of Zero Conf are

  1. Address Selection

  2. Name Resolution

  3. Service Discovery

Service Discovery

Do you speak my language?
  • ZeroConf is a three-layered system with Service Discovery on top of naming and addressing

  • Logical Services as primary entities on the network

  • Discovery/Advertisement of services instead of hardware/software

  • A new device connected to the network should learn the services available in the network rather than being manually configured by the user

Service Discovery

  • Periodic (sensible) querying for services

  • When a service is started it sends out multicast messages

  • When a service stops its sends out multicast "good bye"

  • Leases are given to services, if they are not renewed, the service name will not appear on the list of services on the client device

Address Selection

  • Claiming an IP : ARP messages to know if the IP is already in use

  • ARP Probe : An ARP request with Sender IP as all zeros is sent with a target address that is desired by the host

  • Sender MAC address is put into the ARP req, to identify if the request is from the host itself or some other device desiring the same address


  • After claiming an IP address (by querying for desired IP using ARP requests), a host announces I am

  • Announcing the claim is essential to flush the old MAC-IP mapping in the neighbours' ARP cache

  • Announce the IP by sending Sender and Target addresses as same claimed address

Defending an IP

  • When the host is offline for a while it needs to claim the address again, since some other device could have claimed the address while the host is offline

  • Reply to ARP request from competitors looking to claim what is rightfully yours

  • Back off and choose a different IP in time of conflict

Name Resolution

  • Translate between names and IP addresses without a DNS server

  • A multi-cast DNS (mDNS) server is a distributed DNS server that exists simply because all the machines on a local subnet run a special daemon

  • Daemons running on either sides of a router can’t discover each other, so the .local domain is restricted to the local-link

How does it work?

  • IP multicast query message that asks the host having that name to identify itself

  • The target machine then multicasts a message that includes its IP address

  • All machines in that subnet can then use that information to update their mDNS caches

  • Devices can refer to the target computer by name, eg : ping my_name.local, ssh my_name.local, ftp my_name.local


Apple's Bonjour

Bonjour is Apple's implementation of zero-configuration networking (zeroconf), a group of technologies that includes service discovery, address assignment, and hostname resolution. Bonjour locates devices such as printers, other computers, and the services that those devices offer on a local network using multicast Domain Name System (mDNS) service records.


Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. This enables you to plug your laptop or computer into a network and instantly be able to view other people who you can chat with, find printers to print to or find files being shared.

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