Raspberry Pi, Raspbian, Wireless and BATMAN-ADV for meshing

A project that I have recently been working on has now got to the point where we need to remove some access points and allow Raspberry Pis to do the job for us. 

Why you say? Because they're cheaper (Model A's are £15 now) and also allow more control as the 'router' can also be used for other purposes.

I've used BATMAN adv before in the past, but only through other devices such as Open-WRT routers and Open-Meshs but now it was time to get a mesh functioning for myself.

There is a fair bit of guidance out there, but I found bits missing and nothing quote as straightforward as I was hoping, so the below is my guide to getting two Raspberry Pi units with wifi dongles talking to each other.

1: Download a compiled BATMAN advanced kernel - it doesn't seem to ship with Raspbian. I got it from here. On a side note, Airmesh, where did you go? Your work looked like it was going to be interesting!

2: Install Raspbian to two SD card and boot the Pi's up and login - I won't go into details here as it's been covered oh so many times everywhere else

3: Copy the downloaded file to the following path on both Pi's:
/lib/modules/X.X.XX+/kernal/net/batman-adv/
X.X.XX+ will be your kernal version - there will most likely only be a single folder in there

4: In the above folder, now rename the file to batman-adv.ko (on both Pi's)

4: Run the following on both Pi's:
sudo depmod -a

5: You will most likely need to get BATCTL (batman control) which allows for easier control of BATMAN (again, on both Pi's): 
sudo apt-get install batctl
if it fails, do a sudo apt-get update and then rerun the command

6: Now its time to run batman-adv on both units:
sudo modprobe batman-adv

7: To setup a simple mesh between two raspberry pis, copy and paste the following lines on the first unit:

sudo ifconfig wlan0 mtu 1528
sudo ifconfig wlan0 down; sudo iwconfig wlan0 mode ad-hoc essid my-mesh-network ap 02:12:34:56:78:90 channel 1
sudo batctl if add wlan0
sudo ifconfig wlan0 up
sudo ifconfig bat0 up
sudo ifconfig bat0 192.168.2.1

8: And the following on the second unit:

sudo modprobe batman-adv
sudo ifconfig wlan0 mtu 1528
sudo ifconfig wlan0 down; sudo iwconfig wlan0 mode ad-hoc essid my-mesh-network ap 02:12:34:56:78:90 channel 1
sudo batctl if add wlan0
sudo ifconfig wlan0 up
sudo ifconfig bat0 up
sudo ifconfig bat0 192.168.2.2

9: Check you can ping each other, unit 1 is 192.168.2.1 and unit 2 is 192.168.2.2

10: You can check if BATMAN can see the links by using the originator option
sudo batctl o

And that's it, a basic working mesh. Add more units by copy and pasting the above code and changing the last line (sudo ifconfig bat0 192.168.2.2) to the next IP address (.3, .4 etc)

The above settings will remain until the unit is rebooted, if you need to set it up again after a reboot just following the above from point 6 onwards.

Hope that helps someone