D-Link DSL-2640S/Mel

Saturday, 2 October 2010 D-Link DSL-2640S. I managed to get hold of an almost new d-link sky router today. It didn't cost much as it is locked down to sky, but I was hoping I'd be able to flash it with a standard firmware, so that I can use it as a backup while I try to fix one of my other routers, both of which have hardware issues.

Meanwhile I've got the D-link sat on the side of my desk and am using it as a Wifi access point, while having a go at extracting the password generation code.

Here's a picture of the innards.

It is built around a Broadcom BCM63281KFBG, which according to a pdf I found on the Broadcom website, is a cost effective, low power chip, with support for power management. The Wifi chip is a BCM4313KML1G - single-band, IEEE 802.11n, with dual antenna support, although the router itself is only b and g capable.

As you can see there's minimal shielding on the wireless section, and judging by the PCB, the bcm63281 has an integrated switch. The inclusion of a power button at the rear, proved to be very useful while I was trying to access the shell.

It has four external Ethernet ports, and supports wireless 802.11b & g. The sky firmware includes support for WPA & WPA2, although you can't select WPA2 only. The firmware seems pretty good at automatically selecting an unused wifi channel, however it sometimes picks a channel used by a neighbour, possibly because they have their SSID hidden, so I found it necessary to manually select one.

The wifi signal is a little weak compared to my other routers, probably because of the internal antenna - the bit of steel with a wire attached at the bottom of the picture. I also wonder if they've limited the power output, to avoid causing interference issues due to the lack of shielding. There are unused solder pads on the PCB for a second antenna.

Mounting the router vertically improved the wifi reception by about 15%, and also makes the router run much cooler. It gets quite toasty while sitting on it's rubber feet, as the vents are at either end of the case. The wifi signal still doesn't match that of my other router's though, or even my neighbour's, it is however, more than adequate to reach opposite ends of my house.

Anyway, before trying to flash it, I wanted to try to access the shell, which, as it doesn't seem to have a telnet or ssh server running, requires a little hacking...

Getting root access didn't provide me with that much of a challenge, although the procedure I used did get a little complicated.