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I have Debian/Ubuntu hosts that I connect via an ad-hoc network with the following settings:

board:~# cat /etc/network/interfaces
auto wlan0
iface wlan0 inet static
        address 10.0.0.2
        netmask 255.255.255.0
        wpa-driver nl80211
        wpa-conf /etc/wpa_supplicant.conf

board:~# cat /etc/wpa_supplicant.conf
# IBSS/ad-hoc network with WPA-None/TKIP.
ctrl_interface=/var/run/wpa_supplicant
ap_scan=1

network={
        ssid="adhoc_test"
        mode=1
        frequency=2412
        proto=WPA
        key_mgmt=WPA-NONE
        pairwise=NONE
        group=TKIP
        psk="abcdefgh"
        bssid=F8:D1:11:52:0C:4E
}

These configurations create an ad-hoc WLAN; however, the nodes often get different cell IDs so that they cannot communicate with each other. To prevent it I added a bssid=F8:D1:11:52:0C:4E line; however, nodes don't get the predefined cell ID when they get the cell ID.

My question is how can I prevent nodes from getting different cell IDs? Why does the bssid line not work in the ad-hoc mode?

P.S. I tried these settings on Ubuntu and Debian distributions that have 3.2 and 3.4 kernels. Wpa_supplicant versions that I used were 0.7, 1.0, and 2.0. None work. For the chipset, I am using Atheros AR9271 chipset for the Wi-Fi module.

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3 Answers

up vote 1 down vote

I'm trying to connect some Raspberry Pi via ad-hoc mesh network. And encountered same problem, different cell, or known as "Cell Splitting".

After days of search, I found this great post:

http://tiebing.blogspot.com/2009/12/ad-hoc-cell-splitting-re-post-original.html

So I solved this problem and here is my script:

    $IFC "$IFACE" down
    $IWC "$IFACE" mode managed
    $IWC "$IFACE" power off
    $IWC "$IFACE" mode ad-hoc channel 10 rts 250 frag 256
    $IWC "$IFACE" essid whateveryouwant
    $IWC "$IFACE" key off
    $IWC "$IFACE" ap 11:22:33:44:55:66
    $IFC "$IFACE" up
    $IFC "$IFACE" 10.10.10.10/24 up

The command "sudo iwconfig ath0 ap 11:22:33:44:55:66" forces my ralink5370 into specified cell-id.

Hope this helps.

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Thank you for your reply. I saw your post on stackoverflow as well. I am looking for a solution for wpa_supplicant. The reason is that iwconfig or iw tool provides WEP encryption. My config above has also WEP encryption settings but I will use RSN patch to have WPA2 however iwconfig can only provide WEP as I know. I use bssid on wpa_Supplicant to force device to get the defined cell ID but it does not, I test it on several different embedded boards and desktops, but I experienced the same problem each time. I would appreciate if you know any solution for the wpa_supplicant. – johan Mar 23 at 13:30
In addition to stackoverflow, I would be happy to give the bounty on askubuntu.com/questions/256846/… if I could get a remedy for my problem. Most of all, I would appreciate a lot for the help. – johan Mar 23 at 13:32
Sorry, I tried WPA + Ad-hoc using configuration like yours. But with no luck, all I got is an OPEN(no WEP/no WPA). Are you sure the WPA+Ad-hoc is feasible? – user209528 Mar 23 at 15:32
up vote 1 down vote

Use ap_scan=2 and remove the bssid= line from the configuration.

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Could you please elaborate on why this will solve the asker's issue? – oKtosiTe Mar 26 at 10:37
up vote 0 down vote accepted

the problem was that previous versions of wpa_supplicant does not support the bssid, installing wpa_Supplicant 2.0 solved the problem!

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