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Okay, I am very much a NEWBIE when it comes to these type of connections. So, I searched on this website on how to be able to do this and I came across two promising questions and answers. However, they don't seem to be helping. First, I tried the following question's answer. Ad-hoc setup for pi 3 All I see is a tooltip saying the following for both PI 3 but with different ip address. With this setup, I can't make PIs talk to each other. I don't even know if they see each other even though they are supposed to be on the same network SSID (thayanet). I can't even PING from each other.

Wlan0 tooltip

Then, I tried the second question I found - Connect to Raspberry PI 3 over Wi-Fi direct This question also didn't help me. Once I made the changes wpa_supplicant.conf file, it spit out all sorts of errors such as unsupported drivers, failed to add interface wlan0, etc...

I simply want to setup a Ad-Hoc connection for my two PIs. So, they can communicate with each other. Any help is appreciated.

UPDATE Once I set up ad-hoc on one PI, the other PI sees that network. Now, how do I use this network setup. I try to connect the non-ad-hoc PI to ad-hoc PI and it won't connect.

ThN
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    You NEED to list what YOU actually did, not post links to tutorials. There is one obvious issue wlan0 has a Link-local address – Milliways Mar 30 '17 at 23:15
  • @Milliways I did exactly what those answers said. So, if anything that's what I would be listing here. I didn't deviate from those questions' answers in any way shape or form. – ThN Mar 31 '17 at 12:35

2 Answers2

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You can simply use the iwconfig tools on the both your Pis to join to an ad-hoc network.

use the following:

sudo iwconfig wlan0 mode ad-hoc channel 01 essid my-net

You can use your Link-Local addresses to interact with the pis in general.

A smart way to know your local network Pis can be to use:

ping -I wlan0 224.0.0.1

It is a Multicast Address which will give your pings from the Pis which have the same ad-hoc parameters.

This should most definitely give you the 169.254.x.x address of the Pi within the ad-hoc network.

Networking upon next boot

In best case use the following in your (both Pis) /etc/rc.local file:

sudo nano /etc/rc.local

iwconfig wlan0 mode ad-hoc essid my-net channel 01
exit 0

and add brcmfmac in to your /etc/modules file for availability of chipset on boot.

For further help I have a GitHub repository which can set up Pis (any model 2 or 3) in Ad-Hoc mode with IPv6 Link Local Addresses.

Shan-Desai
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    Can you clarify if you mean to run the identical sudo iwconfig ...command on both Raspberry Pis please? Also, can you clarify what the xx stand for and where OP is supposed to get the actual values from? Thank you. – Mark Setchell Mar 31 '17 at 14:54
  • Good point I will edit the answer. – Shan-Desai Mar 31 '17 at 14:55
  • @Shan-Desai Your answer is great so far. However, once non-ad-hoc PI connects to the ad-hoc pi successfully, I can't ping the ad-hoc PI from the other pi or vice versa. I keep getting Destination not reachable. I did the ping -I wlan0 mypis-ip But I see the network green LED on both PIs blinking once every seconds. – ThN Mar 31 '17 at 15:09
  • Thank you for the improvements - I have upvoted your answer. There is no mention of how to enable/disable a wifi password or how to set the encryption by the way. – Mark Setchell Mar 31 '17 at 15:21
  • Sadly that is not what I have figured out as of yet. WPA supplicant and its features are lacking and will research on it soon. About the connectivity you might have to restart your avahi-daemon sudo avahi-daemon -r – Shan-Desai Mar 31 '17 at 15:40
  • @Shan-Desai I ran your adhoc script. It executed as expected and I tried to do the same as before. Both of my PIs connected. However, I can't seem to PING from either one. So, how do I test the wifi or adhoc connection. Thanks. – ThN Mar 31 '17 at 16:08
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I've successfully done it using link-local networking.

Wiki page: https://en.wikipedia.org/wiki/Link-local_address

Some googling will let you know what needs to be set up. Since there is no DHCP server, each Pi needs a set static address (although it may auto-config and get it's own), and then be configured to access the other Pi via Wifi. I am not sure how to do this, I have only linked mine via Ethernet, but I am sure it's not terribly different.

Brian Warmerdam
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