Project: Automated offsite backups for an NSLU2 – part 3

11 November 2006

Previously in this series: Part 1, Part 2.

I am trying to get my NSLU2 to back itself up automatically to Amazon S3. At the end of the last post, I noted that the device would need new software to make it do so; and while it’s Linux-based, it’s really not designed to be extended like this. Time to go online.

A quick search for “hacking the NSLU2” leads us to an old article at Tom’s Networking. By following the author’s instructions, I was able to get a telnet login into the device as root – not bad for a few minute’s work. Poking around, however, makes it clear that it’s a rather cut-down version of the OS:

# cd /usr/bin
# ls
Set_Led         [               basename        edquota         free            
id              killall         mke2fs          mkfs.ext3       passwd          
quotacheck      quotaoff        quotaon         smbmnt          smbmount        
test
#

…and so on.

Now, the author of the article goes on to explain how to cross-compile stuff so that you can install new software, which all looks useful. So I’ll file that away, but before jumping in and trying to write my own C program to talk to S3… the author’s own NSLU2 page is linked from the article, and from there he links in turn to a site which is clearly the home of the NSLU2-hacking community, who have probably done at least some of the work for me. Perfect.

A quick poke around shows that no-one there has their slug (as they affectionately call the devices) syncing with S3, which is pleasing (in that it’s nice to be first) but annoying (in that it’s nice to have solutions handed to you on a plate). What it also shows is that anyone doing anything interesting is using a non-standard operating system – that is, they have replaced the Linksys version of Linux with another, more capable one. As you would expect from an open-source effort, there are multiple competing versions of the OS – here’s a comparison matrix.

OK, so, to recap – I now know that I almost certainly need to install a new version of the firmware into the NSLU2 in order to get it run the non-Linksys software required to sync with Amazon S3.

The next step is to find out what kind of software I will need to run. A quick offering to the Great God Google gets 1,280,000 hits – the top one is for something called s3sync, which sounds interesting, but the remainder on the first page are pretty much irrelevant. A few more refined searches lead me to this page: A List of Amazon S3 Backup Tools by Jeremy Zawodny. There are a lot of tools listed here, so I think the next stage is to find out what their dependencies are, and work out which – if any – is compatible with at least one of the hacked NSLU2 firmware distros.

Next: Evaluating the software.