This is my first HOWTO. I just wanted to share my experience with this router.

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First: How To flash OpenWRT and enable Wi-Fi

1. Download THIS IMAGE: http://downloads.openwrt.org/snapshots/ … loader.bin
2. Press the reset button until the power led starts blinking. Go to http://192.168.0.1 and upload the image. (DIR-825's LAN port). Let it breath for about 3-5 minutes.
3. Telnet to 192.168.1.1, type in passwd and set your root password. From now on you may use SSH.
4. ssh into the router (192.168.1.1). go to /etc/config/wireless and comment/delete all lines with the following text (delete the entire line):

        option disabled 1

5. type "wifi". Enter. Everything should be OK. Wifi Is working now. Check for the SSIDs "OpenWRT" on both bands.

Note: DO NOT update kmod-ath9k. It will bug the wifi and you will have to re-flash the router (from #2)

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Second: How to put one interface into Monitor mode and still prompt non-beacon packets in tcpdump
Useful in Wireless Mesh Networks

Let me explain this one: I have been struggling to add an interface in monitor mode and watch IP packets in tcpdump but 1) the router has stopped beaconing while on AP (Master) mode and 2) I can't see any IP packet in tcpdump.

IT IS NOT POSSIBLE to put *any* interface into monitor and master mode for the aht9k driver. Even if you create another interface other than wlan0, the interface in wlan0 will stop beaconing and you will no longer be able to use it as an AP.

Moreover, if the interface is set in AP mode, a "mon.wlan0" interface is created automatically. However, if you tcpdump in that interface, you will notice that it will only show beacons.

The only way is to put your router into adhoc mode and monitor mode at the same time. I'm doing research on Wireless Mesh Networks and this worked just fine.

Do the following (replace X.X.X.X with the desired IP)

iw phy phy0 interface add moni0 type monitor
ifconfig moni0 up
ifconfig moni0 X.X.X.X netmask 255.255.255.0

This will create a new interface in the phy0 radio and will be set in monitor mode. You can still see beacons and non-beacon packets while tcpdump-ing.

Remember, your wlan0 interface must be put in adhoc mode. I haven't tested this in sta mode though.

cheers

(Last edited by aztroboy on 16 Feb 2011, 04:50)