There's an old net story from the 80's, which I can't find right now, but is about two computers, 10 feet apart, having a ridiculously long network route between them, packets traveling into other states or countries and back, when they could have flowed over a short cable.

Ever since I read that, I've been collecting my own ridiculously long routes. ssh bouncing from country to country, making letters I type travel all the way around the world until they echo back on my screen. Tasting the latency that's one of the only ways we can viscerally understand just how big a tangle of wires humanity has built.

Yesterday, I surpassed all that, and I did it in a way that hearkens right back to the original story. I had two computers, 20 feet apart, I wanted one to talk to the other, and the route between the two ended up traveling not around the Earth, but almost the distance to the Moon.

I was rebuilding my home's access point, and ran into a annoying bug that prevented it from listening to wifi. I knew it was still connected over ethernet to the satellite receiver.

I connected my laptop to the satellite receiver over wifi. But, I didn't know the IP address to reach the access point. Then I remembered I had set it up so incoming ssh to the satellite receiver was directed to the access point.

So, I sshed to a computer in New Jersey. And from there I sshed to my access point. And the latency was amazing. Because, every time I pressed a key:

• It was sent to a satellite in geosynchrous orbit, 22250 miles high.
  
• Which beamed it back to a ground station in Texas, another 22250 miles.
• Which routed it over cable to New Jersey to my server there.
• Which bounced it back to a Texas-size dish, which zapped it back to orbit, another 22250 miles.
  
• And the satellite transmitted it back in the general direction of my house, another 22250 miles.
  
• So my keystroke finally reached the access point. But then it had to show me it had received it. So that whole process happened again in reverse, adding another 89000 miles travel total.
• And finally, after 178000 and change miles of data transfer, the letter I'd typed a full second ago appeared on my screen.

Not bad for a lazy solution to a problem that could have been solved by walking across the room, eh?

Previously: roundtrip latency from a cabin with dialup in 2011

Following up on propelling disk images, Propellor can now build custom ARM disk images for a variety of different ARM boards. The disk image build can run on a powerful laptop or server, so it's super fast and easy compared with manually installing Debian on an ARM board.

Here's a simple propellor config for a Olimex LIME board, with ssh access and a root password:

lime :: Host
lime = host "lime.example.com" $ props
    & osDebian Unstable ARMHF
    & Machine.olimex_A10_OLinuXino_LIME
    & hasPartition (partition EXT4 `mountedAt` "/" `setSize` MegaBytes 8192)
        & hasPassword (User "root")
        & Ssh.installed
    & Ssh.permitRootLogin (RootLogin True)

To make a disk image for that board, I only have to add this property to my laptop:

& imageBuiltFor lime
    (RawDiskImage "/srv/lime.img")
    (Debootstrapped mempty)

Propellor knows what kernel to install and how to make the image bootable for a bunch of ARM boards, including the Olimex LIME, the SheevaPlug, Banana Pi, and CubieTruck.

To build the disk image targeting ARM, propellor uses qemu. So it's helpful that, after the first build, propellor incrementally updates disk images, quite quickly and efficiently.

Once the board has the image installed, you can run propellor on it to further maintain it, and if there's a hardware problem, you can quickly replace it with an updated image.

computer tower that I will be maintaining with propellor

It's fairly simple to teach propellor about other ARM boards, so it should be quite easy to keep propellor knowing about all ARM boards supported by Debian (and other distros). Here's how I taught it about the Olimex LIME:

olimex_A10_OLinuXino_LIME :: Property (HasInfo + DebianLike)
olimex_A10_OLinuXino_LIME = FlashKernel.installed "Olimex A10-OLinuXino-LIME"
    `requires` sunixi "A10-OLinuXino-Lime"
    `requires` armmp

My home server is a CubieTruck which serves as a wireless access point, solar panel data collector, and git-annex autobuilder. It's deployed from a disk image built by propellor, using this config. I've been involved with building disk image for ARM boards for a long time -- it was part of my job for five years -- and this is the first time I've been entirely happy with the process.

After thanksgiving at my sister's, I got the fun of a big family visit without the turkey day stress. We ate lemons and stuffed three people inside a tree.