[OpenWrt-Users] Belkin N1 router - F5D8231-4 v5000

[DragonK]

Ivo van Geel wrote:
> Hi DragonK,
>
> The CPU seems to be a Ralink RT2880
> (http://www.ralinktech.com/ralink/data/RT2880.pdf).
> This kind of CPU is also used in the T-Com Speedport W700V (see
> http://wiki.openwrt.org/TableOfHardware).
>
> Support for this CPU is a Work In Progress, there is no running version
> of OpenWRT available for this CPU, yet.
> (http://wiki.openwrt.org/OpenWrtDocs/Hardware/T-Com/Speedport_W700V)
> It is going to be very, very difficult to create a running version of
> OpenWRT for your router.
>
>
> Kind regards,
> Ivo van Geel.
>    
Hello everybody,

I've made a little progress since the last mail.

Here is the thing:

I'm trying to reverse engineer the firmware image ( 
http://www.belkin.com/support/article/?lid=en&pid=f5d8231-4&aid=5927&scid=854&fid=4063&fn=f5d8231v5_ww_5.01.05.bin 
) for
this router in order to modify it and perhaps enable the telnet daemon.

This is what I've found until now:

1) The device uses U-Boot
2) The firmware image has the following structure: Belkin header + 
U-Boot header + gzipped kernel + squashfs image.

I've created a template for WinHEX (attached to this mail) which decodes 
the information I've identified in the firmware file.

The problems I'm facing now are the following
- I can't exactly determine the offset of the SquashFS inside the fw img 
based on header information (but it can be located based on its 
signature 'hsqs').
- I don't seem to be able to mount the extracted filesystem.

When I attempt to mount the FS, I get the following:

------------------------------------------------------------------------------
root# mount ./fw_squash_stripped.bin ./a -o loop
mount: wrong fs type, bad option, bad superblock on /dev/loop2,
....

root# dmesg | tail
squashfs: version 3.3 (2007/10/31) Phillip Lougher
SQUASHFS error: zlib_inflate returned unexpected result 0xfffffffd, 
srclength 8192, avail_in 596, avail_out 8192
SQUASHFS error: sb_bread failed reading block 0x712
SQUASHFS error: Unable to read cache block [1c41a8:1d95]
SQUASHFS error: Unable to read inode [1c41a8:1d95]
------------------------------------------------------------------------------

Can anybody help me out here? Has anybody seen anything similar before?

 From what I understand squashfs is able to mount both little endian and 
big endian filesystems so I don't think this is the problem.
Also, my kernel doesn't have the squashfs-lzma patch, but I've tried to 
mount the image using a lzma-enabled kernel and that's not it either.




Also, I have another question:

In this image of the router's board ( 
http://img411.imageshack.us/img411/1251/a31ndiua5sp4.jpg ) , the 
encircled red thing could be a serial port?
If so, how could I connect to it (because the "pins" are only on the 
board, there's no connector) ?


Thanks!