Specs
PCEngines has an overview over the ALIX-line as well as the specs of the ALIX 2D13, so this is just a short rundown:

• 500 MHz AMD Geode LX800 (x86)
• 256 MB DDR DRAM
• 3 Ethernet NICs (Via VT6105M 10/100)
• Furthermore: 2x USB ports, MiniPCI-slot, CF-slot, serial port

I chose the 2D13 model since I wanted 3 ethernet NICs and the added battery (for keeping system time after a reboot) seemed like a good idea. The ALIX boards can be bought in many variations, some even providing VGA/sound to be used as a thin client. I ordered my ALIX at the Varia-Store, where they offer a complete bundle of ALIX-2D13-board, enclosure, power supply and CF-card for a mere €145 including shipping in Germany. I ordered on Tuesday at noon and the package arrived Thursday afternoon.

Operating system / prerequisites
You probably want to run Linux on these babies, otherwise you can stop reading ahead. There are some things you really need before you get started:

• CF-card reader on your computer (for installing the OS to the CF-card)
• Serial connection (think USB-to-Serial converter, pl2303) to access the ALIX

I chose to install Debian on the ALIX, since I’m familiar with it and it has little overhead. I found these guides to be helpful, even if not completely up to date or correct: Guide 1, Guide 2. But careful! Don’t mount the ALIX board in its enclosure until you’re sure that your ALIX boots, since removing the CF-card requires taking the board out again ;).
The next thing I did was to build a custom kernel, since Debian only includes 2.6.26 and has everything you’ll never need compiled as modules. I built a next-to-minimal kernel on my workstation (this site helped a lot) and it seems to work just fine so far. The config is here. An important thing if you compile somewhere else is to make sure you useARCH=i386 make menuconfig
ARCH=i386 make -j3 when configuring and compiling your kernel for the ALIX.
People already using CF-cards or small embedded devices probably know to use noatime where possible and mount /tmp, /var/tmp, /var/run, /var/log, /var/lock as tmpfs to go easy on the CF-cards limited write cycles.

Performance / Applications
I bought the ALIX to play around with it but also to evaluate its possible use as a Samba-fileserver and CUPS printserver for my flat, and maybe even a small shellserver in case I’m away from home and my workstation isn’t running. With an energy-consumption of about 5-6W you can have it running 24/7, the fact that it doesn’t have any moving parts only adds to that. Booting takes a few seconds by the way, not that it matters.

The first measurements I did were with scp from the ALIX to my WS, which maxed out at 3.5MB/s because OpenSSH used up the CPU on the ALIX. Next I tried using Samba (to and from) and got a mere 6.5MB/s throughput reading from the ALIX and an attached USB-drive. This was with the stock kernel however, and using my own 2.6.34-kernel I was able to transmit more than 9MB/s using Samba. I had a stupid line in my smb.conf which might explain the 6.5MB/s I got before. Make sure to remove this line!:socket options = IPTOS_LOWDELAY TCP_NODELAY SO_RCVBUF=16384 SO_SNDBUF=16384I then did another test using fefes gatling web/ftp/samba-server on the ALIX and my USB-drive in HTTP-mode with wget and was able to completely saturate the 100MBit-link, which is why I suspect to be able to do the same thing with Samba as well.
For customers of Aachens Uni-DSL it should be interesting to know that I managed to max out my 8Mbit-DSL-line (about 700kB/s) using vpnc on the ALIX with enough idle CPU left. Using vpnc and doing a git pull on the ALIX resulted in only a slight slowdown since git was busy saving/packing objects it received. Performance using git daemon on the ALIX and pulling from there were acceptable as well.

All of these measurements are highly unscientific and side-effects or misconfigurations could have had negative effects, so one should read these rates as minimal assurances.

Conclusion
After the first full day of using the ALIX I’m impressed. The CPU is powerful enough for most tasks and with a little custom configuration some things can be sped up considerably. I don’t see any problems for the intended use as a file-server, by whichever way the files are served. The next step will be hooking up my printer.

If you intend to use encrypted filesystems on the ALIX you should do some research first. While the AMD Geode does have hardware support for AES, OpenSSL does not seem to use it and I’m not quite sure about any cryptofs. Another common thing the ALIX might be used for is wireless LAN. The MiniPCI-slot can take a variety of wireless NICs, but I don’t need yet another AP at the moment.

Photography
You accidentally selected “Delete All” on your digital cameras and now your photos are gone? You even fear they might have been overwritten by photos taken after the accident? Fear not, the same thing happened to me, and I was able to restore all the photos from the event plus photos going back as far as three months from my CF card in my 400d using the PhotoRec software.

Cameras today often have an orientation sensor, so pictures taken in portrait mode will automatically be rotated. But this usually happens in the viewer, while the orientation is simply an EXIF tag. Of course this takes up precious computing time and not every viewer supports it. jhead can not only display EXIF information in a consistent manner but can also rotate pictures lossless and clear the orientation-tag afterwards. The call is jhead -autorot *.JPG
If you want to rename your images using EXIF-information, exiftool is the way to go. The command exiftool '-FileName<Party_ ${CreateDate}_${filename}' -d %Y%m%d *.jpg would prefix all the photos with “Party” and the create-date, while keeping the original filename as the suffix. exiftool can shift dates too, if you ever forget to adjust for daylight saving.

When uploading the images you’ll often want to resize them. The ImageMagick collection can do just that, and many other things (like sharpening etc.). If you mogrify -resize 1600x1600 your photos will be resized to 1600px maximum edge length, while keeping the ratio. But be careful, mogrify overwrites the pictures in place!

Music
Thanks to services like video2mp3.net/ you can download a lot of music from YouTube. But sometimes there is silence at the end or the beginning of a song, and a whole collection of songs might have differing levels of volume. To cut an mp3 you can use mp3splt like this to cut everything after 03:30 minutes:mp3splt file.mp3 00.00 03.30The sound levels can be normalized, losslessly, using mp3gain:mp3gain -rk *

Misc
When pretty-printing flat text files I use a2ps to format them nicely and get a PostScript-document. a2ps however does not support UTF-8, while the only characters I care about (German Umlauts) can be represented using Latin1 just fine. So, one can use iconv to convert them on the fly like this:iconv --from-code=UTF-8 --to-code=LATIN1 textfile.txt|a2ps --font 9 -E -B -r --column=1 > out.ps

To export images from a PDF-file I discovered pdfImages, which is part of the xpdf-suite. Use it like this:pdfimages -j foo.pdf bar

Reusing a connection
Anyway, today I wanted to present another advanced feature, one I only stumbled upon while learning for an upcoming exam. The slides mentioned the possibility to share connections on one SSH-channel (to the same destination, obviously). Now, why do you need more than one connection in the first place? Well, sometimes you just need the space, and using screen just doesn’t cut it. Or you use git or scp to the same host you’re logged in already interactively. In that case, you just have to establish one connection and any further connection will use the first one. The benefit? Login is way faster, almost instantly, because the whole handshake and authentication doesn’t have to take place again. The caveat: You’ll have to close your master-connection last, otherwise the other connections will drop too. For me that’s no problem, since the host I use most of the time is also the host I’ve got a session open with 24/7 (IRC).

I’m just gonna show the fully automated version here, though you can use it manually as well, just when you need it. A better description can be found here. To automate it, put this in your ~/.ssh/config (you don’t have a config yet? shocking!):
ControlMaster auto
ControlPath /tmp/%r@%h:%pAs usual, you can put it at the very top to apply for all hosts or you can activate it for specific hosts by putting below a Host declaration. Now all you have to do is use ssh host as usual. You’ll see it’s working when you terminate the connection:
Shared connection to host.de closed.

Reverse tunnel
Yes, you can tunnel with OpenSSH. You can even have it act as a SOCKS proxy, which is really neat when combined with Firefox-plugins like FoxyProxy. But you can also reverse-tunnel your way out of a closed network (or NATed network for that matter) when you don’t have access to any intermediate host (like the router/firewall). It’s easy:
ssh -NR 12345:localhost:22 home.deThis assumes you’re issuing the command from the machine that you want to access (from home) later on. It will bind the port 12345 on home.de so that it is forwarded to port 22 (SSH) on the local host. Yeah, it requires some reverse thinking too to get it right ;) The -N-switch prevents a login, by the way. Obviously it is of little use if your home.de has a flaky dialup connection, so you might want to reverse-tunnel to a stable endpoint (or use something like autossh).

Results
When are the effects of a softbox most obvious? Probably when there is absolutely no other light-source around (see my Black/White collage). It becomes even more obvious if you photograph something in front a background where it casts shadows. One thing I had to do was to increase my flash exposure compensation (i.e. make it brighter), and in a few cases I had to manually set the white balance, though that’s something I do very often anyway. And using the P-mode seems like the only usable way to incorporate the flash easily. I guess I’ll have to read up on the difference between “Green Square” and “P” again. If you can I’d try to build a bigger box and of course the flash should be close to the center (which can’t be done with the internal flash).

Bottom line
After quite a few shots (photographing people is probably the most rewarding) with my selfbuilt softbox and I know now that the money for a professional one will be well spent ;) If anyone knows of good brands for a) flashes (for Canon) b) softboxes c) remote flash triggers (wireless), let me know!

Rest assured, I’ll be there, but probably less cubing and more photographing. So be sure to come by, even if just to get a glimpse of hardcore-nerds in a different area than your own profession. In case you missed the last Aachen Open, be sure to check out last years website for impressions.

Comments and improvements can be directed to me via email or as a comment to this post.