I own an old DVR (Digital Video Recorder). My initial goal was to use it with its default Linux system, but I don’t know the root password and there doesn’t seem to be any vulnerability. I technically have the password hash, but it is protected with md5crypt. I tried common wordlists, but none of them were successful. Maybe I’ll try again later.

So I thought, why not build a new Linux for it? I have no prior experience with this, but first I need to back up the existing firmware so I can restore it in case something goes wrong. I also need the DTB (Device Tree Blob), as far as I understand.

Because of this, I want to dump everything using U-Boot. However, this U-Boot version is very old, and I haven’t been able to locate the DTB so far. I’ve read the documentation, but if there are any mistakes or misunderstandings in my explanation, I would appreciate it if you could point them out.

In short, I need help with the U-Boot part. I need to dump the kernel, firmware, or DTB.

Thank you.

Note: My native language is not English; the translation was done using AI. Please excuse any errors. I am connecting to the device via UART.

CPU:HiSilicon