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My goal is for two or more devices (incidentally LinkIt Smart 7688s) to communicate over WiFi in a field situation where there is no access point such as a Wifi router. It's preferable that all devices are "peers", i.e. I'd prefer there not be one "special" device that acts as an "Access Point" for the others. Also preferable that no DHCP server is required.

I've configured the devices for an Ad Hoc networking with link local addresses. I run the same commands on each device except that I bump the last number in the ip for each.

modprobe mt7603e
iwconfig wlan0 mode ad-hoc channel 11 essid my-network
ifconfig wlan0 up 169.254.0.2 netmask 255.255.0.0
# In above commend  I replaced 169.254.0.2 with 169.254.0.3 on 2nd device

They appear to join the same network, the first device reports:
wlan0: Creating new IBSS network, BSSID 2a:fa:72:1d:eb:56

And the second device reports:
wlan0: Selected IBSS BSSID 2a:fa:72:1d:eb:56 based on configured SSID

Note that the second device appears to have "selected" the network that the first device created.

I thought this looked promising, however trying to ping one device from the other fails:

ping 169.254.0.2
PING 169.254.0.2 (169.254.0.2) 56(84) bytes of data.
From 169.254.0.3 icmp_seq=1 Destination Host Unreachable
From 169.254.0.3 icmp_seq=2 Destination Host Unreachable

One device cannot ping the other. Incidentally each device can ping its own ip successfully.

I'm running a custom Linux created using Build Root so I don't necessarily have access to all the tools you would get on a more standard Linux install but I have or can get many of the common ones.

Thanks so much for reading. I'd really appreciate any suggestions for troubleshooting this!

For what it's worth here is the output of ifconfig and iwconfig, this is from one device, the other device reports identical results aside form ips and mac addresses. I checked both and the Cell that's output in iwconfig is the same for both:

# ifconfig
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:20 errors:0 dropped:0 overruns:0 frame:0
          TX packets:20 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 
          RX bytes:1515 (1.4 KiB)  TX bytes:1515 (1.4 KiB)

wlan0     Link encap:Ethernet  HWaddr 9C:65:F9:1B:83:99  
          inet addr:169.254.0.3  Bcast:169.254.255.255  Mask:255.255.0.0
          inet6 addr: fe80::9e65:f9ff:fe1b:8399/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:14 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:1152 (1.1 KiB)

# iwconfig
lo        no wireless extensions.

wlan0     IEEE 802.11  ESSID:"my-network"  
          Mode:Ad-Hoc  Frequency:2.462 GHz  Cell: 2A:FA:72:1D:EB:56   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off

eth0      no wireless extensions.

Update: In addition, here is the output from ip route show:

# ip route show
169.254.0.0/16 dev wlan0  proto kernel  scope link  src 169.254.0.3
  • Welcome to SuperUser. My guess would be missing routing for the local network, paste us output from ip route show or route commands. At least one of them should be part of your standard network tool package. – Marek Rost Mar 17 '17 at 18:19
  • Thanks Marek, when I run # ip route show, I get 169.254.0.0/16 dev wlan0 proto kernel scope link src 169.254.0.3. – Bruce Mar 17 '17 at 18:44
  • That seems in order. Are you sure that Ad-Hoc networking is supported by the hardware? This made me uncertain: forum.openwrt.org/viewtopic.php?id=63697 – Marek Rost Mar 17 '17 at 19:16
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It seems that LinkIt Smart 7688 doesn't support Ad-Hoc wireless mode. Only access point and station are supported by the hardware.

  • Thanks Marek! You saved me from any more frustration on that. I didn't realize that not all Wifi devices supported Ad Hoc. – Bruce Mar 17 '17 at 21:44

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