No Open Blockers

I came to the realization that I have too many computers constantly running in my house. It’s not so much a “go green” thing to use less electricity as it is me being cheap and wanting to lower our bill. It’d also be nice to walk in a room and hear silence rather than whirring computer fans or have to clean dead spiders from multiple desktops. After reading an article in Linux Journal about hacking the MyBook (external network drive that runs linux under the covers), it looked like it could serve a lot of uses, starting off with being the house file server and backup system.

So far, I’m off to a good start. To begin with, the Linux Journal article is already somewhat obsolete as there’s no need to hack it anymore. The latest firmware flat out gives you the option to enable SSH on the device; once you’re in you can do pretty much whatever you want. One click in the web UI and one terminal later, I was logged directly into the system.

The MyBook runs BusyBox linux. I’ve never worked on a stripped down linux install like this, but other than missing a few commands I’ve come to love (I continue to type less; my brain just refuses to acknowledge that it’s not there) it’s pretty easy to navigate if you’re comfortable on linux.

Initial Setup

-> nmap -sP 192.168.0.1/24
 
Starting Nmap 4.76 ( http://nmap.org ) at 2009-06-16 17:42 EDT
Host 192.168.0.1 appears to be up.
...
Host 192.168.0.112 appears to be up.
...

I snipped out the rest the results, but you get the idea. I only have a handful of non-static IPs internally so it wasn’t too hard to figure out which one was new. The box runs lighttpd and has a pretty slick (albeit a bit slow) interface to most of its guts, so after digging the included CD out of the trash to look up the default password, I was able to connect to it and start dorking around.

The MyBook comes with a lot of features, with the small caveat that I don’t actually need most of them. So the first thing I did was run around disabling things. It’s very cool that the device supports Samba and AFP, but frankly, I just don’t need them (I’ve had the wife running linux for years now, she rocks). I also killed FTP and the Mionet software. It wasn’t all slash and burn; I enabled SSH and NFS and made a new user for myself. Ultimately I’ll turn off the daemon that controls the slick white light on the front of it, but the novelty is still there and it looks damn cool at night (and really creeps my wife out since the light pulsates).

At that point, I was able to SSH into the box and (potentially) really get myself in trouble.

Enabling Cron

Cron is on the system, but it doesn’t work out of the box. I had to make one small change: creating the directory in which it’s going to store the schedules.

mkdir /var/spool/cron/crontabs

Here’s where I got lazy. I just set the permissions on the cron and crontabs directories to 777 to make my life easier. It’s far from secure, but I’ll work on that later. For now, I just wanted to get my non-root user to be able to schedule things.

The other change that needed to be made was to start the crond daemon. I didn’t find anything in the web UI to support this, but given the rate at which the firmware is exposing functionality I wouldn’t be surprised to find it there in the near future. I hacked up a pretty rudimentary init.d script so it would auto-start on reboot and was on my way.

SSH

The main issue is that the home directory for all created users is simply defaulted to /shares. That directory serves as the root of all of shared files. Not that I’m expecting to create a ton of users, but I didn’t like the idea of a single .ssh directory for all users. I didn’t find any user mod tools on the install, so I just changed the /etc/passwd file to give my user a different (read: private) home directory. After that, it was as simple as running ssh-keygen like any other linux system (I won’t get into those details here, but it’s pretty easy to google around for generating SSH keys).

After installing the public key on my webserver, I was good to go for automatically logging in.

Rsync

Profit

I’ve also copied over the “family” shared files to the MyBook, such as music and pictures. It was done simply through NFS so I won’t go into details here other than to say that there were no unexpected hiccups in the process.

There’s more I want to tinker with on the box. The web UI is in PHP and after a bit of looking around, I was able to find and start editing the web UI site. I’m thinking of adding my own section that will at very least report on the previous night’s backups. I’ll get to that eventually, for now I’m happy to have replaced one of the desktops in my house.