Promiscuous mode lost!
 

Hi

I've been having a lot of fun with wireless promiscuous mode on my N900 but on two or three occasions now, that promiscuous 'magic' has vanished and no amount of re-boots or $sudo ifconfig wlan0 promisc can recover it. All I could pick up were multicasts. The only way to recover it has been to re-flash.

Now, the other day when everything was working like a charm I foolishly fiddled with a couple of things. Nothing major, if I remember correctly it was to switch off my Skype status which I rarely used, and also to load a couple of updates that were flashing in the top status bar (recorder and 3G/2G switcher applet). Suddenly the magic was lost and all I could see were multicasts. I then noticed TCPDUMP gave the following message which I dont remember seeing before - but I may be mistaken and this is not relevant:

Nokia-N900:~# tcpdump -i wlan0
tcpdump: WARNING: can't create rx ring on packet socket 3: 92-Protocol not available
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on wlan0, link-type EN10MB (Ethernet), capture size 96 bytes

OK, so I have a backup, why not just re-flash and get the promisc magic back? Well I've done so now twice and I cant seem to get it back. What has happened? BTW I only flash the combined BIN file as this leaves the rest of the N900 (photos etc) in tact. I dont really want to do a complete factory reset.

Does anybody out there understand the workings of tcpdump and promisc mode sufficiently well to help? Is it some kernel module getting screwed up? I only use the standard Nokia kernel as it is compatible with Joikuspot.

How do I get the promisc magic back? Help please!

Re: Promiscuous mode lost!
 

N900 has some form of promiscuous mode without power kernel? I could've sworn you could only get the monitor aspec on power kernel and injection only on power kernel with lxp's drivers...

I remember in the early days people were messing with the N900 trying to get monitor mode working. I don't think it ever worked reliably on the N900's stock firmware. How badly do you need JoikuSpot, vs. the free wifi hotspot program that works with power kernel?

Re: Promiscuous mode lost!
 

Thanks for the response. I was not aware of the free hotspot - I'm more than happy to give it a try if using the advanced kernel will give me promiscuous mode back.

Just to be clear, I'm not really interested in monitor mode, which will allow an un-associated wireless device to read the wifi beacons as well as any actual data packets.

What I want is promiscuous mode. If I am associated with a wireless network as device A, and the wireless network also has a unicast conversation going on between B and C, then I want to be able to read those unicast packets, e.g. with Wireshark. I've had it working just as described in this link and then, suddenly, it is gone and all I can see is multicasts.

http://www.knownokia.ca/2010/04/usin...d-profit.html#

Re: Promiscuous mode lost!
 

I found that neither flashing the enhanced kernel, nor flashing back to the stock Nokia kernel made any difference to promisc mode.

However, I have now re-flashed from the USB cable and this time, I was pressing the U key as I connect the USB cable as per the wiki instructions. Pleased to report that this time promisc mode has been restored! As a side note, I think I failed to press the U key during the last couple of re-flashes. Does that really make a difference? Perhaps it does!

I would conclude that it is not a kernel issue, but more likely something to do with a driver for the wireless chipset that gets replaced without warning during some package upgrade. I hope to work out the offending package or at least work out a way of taking a backup of this precious config that can be restored without a re-flash. Once again, any help from people who actually understand this stuff would be most welcome!