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Keywords: Network Attached Storage, Linux
Title: Linksys NSLU2
Verdict: Highly recommended
This is a first, here at TechBookReport we don't normally look at hardware - we're happier focussing on books, tutorials and software reviews. However, in the case of the Linksys NSLU2, affectionately known as the Slug, we're willing to make an exception. Not only is the Slug a rather nifty little network attached storage (NAS) device to have on your network, it's also a hackers delight that can be put to use as a general purpose Linux box for print serving, development, web serving and much more.
Out of the box the NSLU2 is a small, stylish looking box no larger than a 3.5" hard disk. It's designed as a low-cost NAS device, with an ethernet connection to the network and a couple of USB ports for attaching hard disks or USB flash drives. Internally the box runs a stripped down version of the Linux operating system that runs Samba to create the disk shares that make any connected drives available to users on the network. A web front is available so that users can configure the drives, create shares, set up disk quotas and so on. Be aware that drives configured by the Slug are formatted with a Linux file system (EXT3), so cannot later be removed and plugged straight into a Windows box.
So far so good - while the documentation is scanty, the web interface is clear enough and it's possible to install the device, connect the hard disk and have instant NAS functionality on your network in a matter of minutes. However, what makes the Slug really interesting is what you can do with once you've replaced the official Linksys firmware with one of a number of alternatives. Note that these alternatives have no official Linksys support - so tread with care… What all of these alternative firmware images have in common is that they expose much more of the Linux operating system than the Linksys software does.
The most straightforward of these alternatives is called Unslung, and it works by building on the existing Linksys firmware rather than replacing it completely. For the user who's not overly familiar with Linux but isn't afraid of the command line, this is probably the best option to take. Other alternatives include Debian, SlugOS, OpenSlug and more. These generally require greater levels of Linux experience, and they do without the Linksys web front end.
The actual process of replacing the firmware is fairly straightforward. Firstly it's advised that you upgrade to the latest official release of the firmware from the Linksys site - there's an upgrade option available from the Slug web front end. Once you've upgraded it's recommended that you familiarise yourself with the emergency procedures which might be necessary if you manage to screw things up. When you're confident enough it's just a case of downloading the unofficial firmware image and following the detailed instructions published on the NSLU2 - Linux home page. For the rest of this article we'll assume that your NSLU2 has been upgraded to run the Unslung firmware.
After upgrading to Unslung it's a case of rebooting your Slug and just checking that you can still copy files to and from it, create new disk shares, add users and so on. You'll also notice that the web front end now features the obligatory Linux penguin and a new menu option to enable telnet. Selecting this option allows you to then open a telnet session and hey presto you're connected to a fully functioning Linux server.
There is an impressive array of software available for the Slug, and downloading and installing is usually painless even for those with limited Linux skills. An Unslung box can be used as a print server running CUPS (you can plug a USB printer into the Slug and then share it across the network), it can be used as a web server (there are a variety of web servers available, including Apache and Lighttpd ), developers can use it as a CVS or Subversion box for source control, it can be used as a media server, a Java box (though it can't run the Sun JVM, others are available however) and more. Oh, and you can use it as a NAS device as well…
What's impressive is that all of this functionality comes in such a compact little package. You get the benefit of having a Linux server to hand, but it's tiny, silent and draws very little power. Sure, it's not a box you'd use to run big, beefy production loads, but it's a great little box all the same. Highly recommended.