Ad-Hoc Wi-Fi Network Setup

On Mon, 30 May 2011 03:13:16 -0400, William Hopkins writes:
> On 05/27/11 at 08:03pm, Volkan YAZICI wrote:
>> On Fri, 27 May 2011 16:56:39 +0000 (UTC), Camaleón writes:
>> > "ifdown/ifup" and maybe "/etc/init.d/networking restart" just to be
>> > sure
>>
>> My /etc/network/interfaces is empty, but loopback device. I'm just
>> issuing plain old ifconfig, and IMHO it should be working. I need to
>> find a way to get more details about the problem, about why it doesn't
>> work.
>
> I agree. It's best to start with ifconfig/iwconfig anyway.
> When you set 'foo' to ad-hoc, can you scan from 'bar' and see it?

Below are the latest diagnostics.

1) I configure 1st machine as follows.

# iwconfig wlan0 mode ad-hoc chan 1 essid foo
# ifconfig wlan0 192.168.1.1"

"dmesg | tail" tells me that it just has created a new ad-hoc
network:

wlan0: Trigger new scan to find an IBSS to join
wlan0: Trigger new scan to find an IBSS to join
wlan0: Trigger new scan to find an IBSS to join
wlan0: Creating new IBSS network, BSSID 02:21:1a:46:0f:1a
wlan0: no IPv6 routers present

2) Let's see if everything is set right on the 1st machine.

# ifconfig wlan0
wlan0 Link encap:Ethernet HWaddr 94:0c:6d:ea:b5:a4
inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::960c:6dff:feea:b5a4/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:212 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:32705 (32.7 KB)

# iwconfig wlan0
wlan0 IEEE 802.11bgn ESSID:"foo"
Mode:Ad-Hoc Frequency:2.412 GHz Cell: 02:21:1A:46:0F:1A
Tx-Power=20 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Encryption key:off
Power Management:on

# iwlist wlan0 scan | grep -C 5 foo
Cell 30 - Address: 02:21:1A:46:0F:1A
Channel:1
Frequency:2.412 GHz (Channel 1)
Quality=70/70 Signal level=0 dBm
Encryption key:off
ESSID:"foo"
Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
9 Mb/s; 12 Mb/s; 18 Mb/s
Bit Rates:24 Mb/s; 36 Mb/s; 48 Mb/s; 54 Mb/s
Mode:Ad-Hoc
Extra:tsf=0000000000000000

3) Ok, now let's configure the 2nd machine.

# iwconfig wlan0 mode ad-hoc chan 1 essid foo

It should directly get connected to 02:21:1A:46:0F:1A cell. Let's
check that.

# iwconfig wlan0
wlan0 IEEE 802.11bgn ESSID:"foo"
Mode:Ad-Hoc Frequency:2.412 GHz Cell: 02:21:1A:46:0F:1A
Tx-Power=20 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Encryption key:off
Power Management:on

Cool. Let's assign an IP as well.

# ifconfig wlan0 192.168.1.1
# ifconfig wlan0
wlan0 Link encap:Ethernet HWaddr 94:0c:6d:ea:c2:4b
inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0
BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:158 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:25560 (25.5 KB)

Can we really see the remote ad-hoc network?

# iwlist wlan0 scan | grep -C 5 foo
Cell 26 - Address: 02:21:1A:46:0F:1A
Channel:1
Frequency:2.412 GHz (Channel 1)
Quality=70/70 Signal level=-19 dBm
Encryption key:off
ESSID:"foo"
Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
9 Mb/s; 12 Mb/s; 18 Mb/s
Bit Rates:24 Mb/s; 36 Mb/s; 48 Mb/s; 54 Mb/s
Mode:Ad-Hoc
Extra:tsf=00000000164ef18e

4) Ok, now here comes the problem. I can neither ping 192.168.1.1 from
192.168.1.2, nor ping 192.168.1.2 from 192.168.1.1.

I'll be really appreciated if somebody could repeat above steps and tell
me whether it works or not.

Best.