I have be using a linux set-top-box for a few years. It has a HDD bay, usb port and TV tuner for recording HDTV programmes and playing media files. It runs a kind of linux that has only very limited os features. Commands are mostly from busybox. It also has LAN port to connect to internet but I didn't use it until recently. The problem is that its root does not have password set. I am trying to set up a password for root but encountered the follow problems:

1. I am able to telnet to it and use "passwd" command trying to set password for root. After input new password twice, it failed with "segmentation fault". I then retry after "mount -o remount,rw /" but same result. What's wrong?
2. Failed to use command, I turned to "vi passwd". Its first list is "root::0:0:....". So I insert a password between the first "::" and save. After that, I am not able to logon again. Have to flash the firmware again. I understand this is a proper way to add password for users. But why it didn't work for root?
3. Its firmware is flashed by using usb with a install.img file. I use 7zip to open it and managed to locate the "passwd" file. I can change it to add password for root. But I don't know if I can use 7zip to re-pack it and rename it to .img. Will it works if I do it in Windows? Or must I do it in linux? What is the proper way to modify the img?
4. Is there any other way to add password for root?
5. Where should I look for if I want to add/install software to img? or to HDD?

Please help.

Without knowing the kernel version etc I would assume the actual password is stored in the /etc/shadow file. With a /etc/shadow file an x indicates a password in that spot i.e. root:x:0... Even if the box did not use a shadow file the password is encrypted and would need to know the type to actually create something usable.

Not enough information to say but it could be a problem with the busybox passwd command. It might be possible to add a password using the chpasswd command which I think is included in busybox.

Again not enough information about the embedded system in the box but you would need to setup a cross compiler for the processor type and be able to add the binary code to the image. I assume that the hard drive is just for recordings and possibly some configuration data. The operating system resides in flash memory on the board.

I tried to gather some hardware related commands and produced a list on the h/w info of the STB. I also did a "ls -ilR" at the root folder. With these info I hope somebody can teach me how to set the password of root. Without password protection, it is too risky to connect it to internet. please help.

Attached Files

	hwinfo_result.txt (10.6 KB, 58 views)
	ls-ilR_dos_01.txt (250.4 KB, 21 views)
	ls-ilR_dos_02.txt (253.7 KB, 10 views)
	ls-ilR_dos_03.txt (254.8 KB, 14 views)