HOW TO get started with OpenNAS.
The OpenNAS software can be used as a replacement for the firmware contained in several low-cost Network Attached Storage devices, including the ALLNET6250, the Gigabit NAS NS-01 and several others. The project homepage is here.
As the project documentation is mostly in German, the following sections will attempt to summarize the information you need to get started.
Interacting with the NAS
The NAS mainboard has a serial port that is accessible via a 4-pin connector. Because that connector uses TTL signal levels, you first need to obtain a cable that converts TTL to RS-232 so that you can connect your COM port to the NAS. I used a mobile phone cable (LG DK-15G) for this purpose.
Once you have a connection, you will see that the NAS gives you 3 seconds to type a Space character to interrupt the boot procedure. You can then interact with the UBOOT bootloader and enter commands to download and image from a TFTP server, copy the image to Flash Memory, and then boot the new image.
Restoring the original firmware
The novice user may want to revert to the original firmware in the device, so here is a description of the procedure:
Download the original firmware from here.