I don't have a Dahua DVR but I just got a Dahua Camera and started looking around a bit. From what I read here the camera and the DVR appears to be running the same software... On my camera there is no FTP server installed, so you need to telnet into your DVR and FTP out files that you wish to look at, using 'ftpput'. To do this you need a FTP server running somewhere where you can upload files. There is also some basic unix commands that are implemented in Busybox but to which Dahua didn't put symlinks, like df and top. To run them you need to issue 'busybox df' and 'busybox top'. Useful to find out how much space is left on the camera, or how much CPU is used.
Buellwinkle, you seem to have it right with SquashFS, it looks like you'll have to dd the partition in a temp file, ftpput it somewhere, unsquash it, change the logo, re-squash it, ftpget the new file on the dvr/camera, and dd again the file to the partition. I don't have the camera running right now but with df it's easy to find the mount point. BTW you work in IT?
On a side note, if anybody is interested, there is a way to get a snapshot of the camera in HTTP, it's not a MJPEG feed, only a still JPEG. But anyway it's not that bad, I was able to get about 3fps out of the snapshot URL with ZoneMinder. It's definately better to go with the RTSP feed but it's quick & dirty if you want to have an idea of what's going on at home while you're away. Here it is:
I believe you can add ?channel= to the URL if you want to select which camera you want on the DVR, it doesn't do anything on my camera for obvious reasons Oh and it appears to require NO PASSWORD, so draw your own conclusions!!