Shrinking the keyring

Nov 2, 2008 / 0 comments

Apparently I'm supposed to be blogging once a day, every day, for November. I missed yesterday and doubt I'll have something to say every day, but let's try...

Today I have been playing with the export-clean and import-clean options to gnupg, in particular in conjunction with the debian-keyring. The options result in only signatures that can be verified (ie that are from keys that exist in your keyring) being allowed, and remove signatures other than the revocation from revoked keys/uids.

Why is this interesting to me? Well, a number of reasons:

  • It makes key updates a hell of a lot easier. It cuts down on the number of new signatures to check, for example.
  • It cuts down on the keyring size, meaning smaller uploads for me and smaller downloads for everyone else. The .deb goes from 20M to 6.6M and the installed debian-keyring.gpg from 24M to 7.6M. That's a signficant saving.
  • It makes for "cleaner" keys; only signatures that we know are valid end up remaining on the keys, anything invalid is removed.
There's an argument that this "weakens" the web of trust (after all, we're throwing away signatures from keys), but I'm not really convinced. The full keys can still be downloaded from the keyserver network and it's not like any of the Debian infrastructure scripts make use of web of trust; all that's important is that a key is present in the keyring. I've been asked about export-minimal (i.e. keys + self sigs only) in the past, but I prefer this method of keeping verifiable signatures as it provides some measure of checking key trust for people importing the keyrings locally or auditing the keyring.

(Note I haven't actually rolled any of this out, it's just something I've been playing with locally at present to get a feel for the savings/benefits to be had.)

Asus EEE 901

Oct 4, 2008 / 0 comments

As mentioned I bought an EEE 901. The battery life was the clincher. I've had it for about 3 weeks now, but have only really been using it for a week - since I finished doing my mobile broadband survey and got an Orange contract.

I can't really comment on the supplied Xandros install. I used it for a week or so, with Firefox + a shell for ssh (Ctrl-Alt-T IYF) but once I found time I installed Debian. I used the EEE installer which I think mainly does the appropriate ethernet driver magic without faff. Certainly went smoothly and all up and running minus wifi, which was soon sorted out with the rt2860-source package. Ethernet, bluetooth and camera all seem fine. SD reader is a USB device that appears when a card is inserted.

Battery life rocks. I can use it on the morning on the train (1hr30 or so), suspend to ram all day, use it on the train on the way home and then around the house in the evening without needing to charge it up. And that's while powering the USB 3G dongle and without any real tuning in terms of trying to save power by dimming the screen etc.

The keyboard *is* small. I wouldn't want this to be my main machine. However it is just about touch typable and the overall machine size is superb - even if I get a bad seat on the train I can still unfold the screen fully and it's my arms/elbows that end up being the issue rather than the laptop itself. I also notice the decrease in screen resolution down to 1024x600 (my old laptop is 1024x768); I can't fit enough xterms. :)

Speed seems fine too. I've not really pushed it hard (I've been resisting installing build-essential) but for a handful of xterms and Iceweasel it's doing a fine job. Equally firing up mplayer resulted in perfectly smooth playback of some mpeg4 over the network. Must actually remember to put something on it to watch on train journeys...

Speaking of train journeys the Orange dongle has integrated without too much hassle. 2.6.27-rc kernels have the appropriate hso driver but I found it caused crashes in areas of low/no signal. Patching up to the latest 1.6 driver solved the problem and adding PPTP to my work VPN into the mix means I can use offlineimap to pull mail locally and then read it with mutt on my journey even when the signal is fluctuating. Hopefully ridiculous starts can be mostly a thing of the past if I can get work done on the train.

What else to say? I'm quite liking the trackpad. The buttons are a bit stiff, but I'm getting used to the double tap, or tap and drag gestures in a way I never seemed to on the R200. Wifi reception seems fine. All in all I'm happy with my choice; the small keyboard is the main drawback and that's the (acceptable) price I pay for a small laptop.

Which data contract?

Sep 28, 2008 / 0 comments

I bought an EEE 901. More on that later.

For the past few weeks I've been trying to work out which "mobile broadband" provider to go with for my daily commute. It's a train journey from the north coast of Northern Ireland to Belfast and goes through some sparsely populated areas, so I wasn't expecting to get anything that would provide 3G all the way. However I do want a provider that can do their best to keep a session up for the journey, handing over between 2G + 3G as necessary. Coverage maps/checkers aren't too bad if you just want to check a static point, but really even then it's better to actually try the provider in the location yourself. So, armed with a bluetooth GPS (BlueNEXT BN-909GR), an Option GT 3G Quad PCMCIA card and my laptop I set about measuring signal strength along my train journey for each of the 5 providers available. I also made sure to actually try a session with them for at least one journey, because signal strength is not everything.

I wrote some Perl using Net::GPSD and Device::Gsm to query my current location, signal strength, 2G/3G status and network every 10 seconds. I did this for 3 train journeys (except for O2) and then also produced an "optimistic" file of all the data points combined for that provider.

A second piece of Perl took this data and drew the maps you see below. The graph on the right for each provider is all data points. Red means 2G, blue means 3G, green means "Limited Service" (i.e. it could see a signal, but not one it was allowed to connect to). White means that we had a GPS location and no signal at all. Click on the maps for bigger versions. You can see the route on OpenStreetMap - my graphs are a little squished horizontally, but the journey is from Castlerock (top left on the coast near Coleraine) to Belfast (bottom right).


At first glance 3 look to be the best bet. Lots of blue, a reasonably priced data plan. Except they can't hold up a session to save themselves. Not only does a 2G/3G handover almost always seem to result in a drop, but I had periods of failing to get a 2G session up at all and had some random drops while in 3G coverage as well. So strike them off.

O2 and T-Mobile don't manage any 3G outside Belfast (that's the bottom right corner btw). I found that a few periods of 3G along the journey helped a lot; it meant I could do a quick mail sync rather than the long drawn out affair it was on a 2G connection. They can both handle handover between 2G/3G and keep a session up for most of the journey, but the lack of speed counts them out.

Vodafone managed the worst reception, which is disappointing. I found them quite good when I lived in England (my datacard is from a Vodafone Pay as You Use data contract). I did find sessions being dropped during the no signal regions, so they just don't seem to be a good bet.

Which leaves Orange. I've had issues with Orange and data in the past (pre 2004 IIRC) but in testing they were able to keep a session up between Belfast and Castlerock, handling 2G/3G handover fine. Coverage was reasonably good and they manage 3G at several points along the journey (the blue points roughly correspond to Coleraine, Ballymena, Antrim and Belfast). I understand Orange have some EDGE capability, but my card doesn't do EDGE so I've no idea if that'll be an extra gain or not. I had a few issues with getting dud DNS servers but this happened with the other providers too so I was beginning to suspect the datacard of playing up. Manually setting known good servers in resolv.conf worked fine.

So, before I go and sign up to an 18 month Orange contract, what have I forgotten?

Which netbook?

Sep 10, 2008 / 0 comments

I think I want a netbook. Although I'm still happy with my R200 (especially since I replaced the battery) something smaller would be handy for the train and general carting about. With the R200 being 12" I'm more drawn to the 8.9" variants; 10" isn't a lot smaller and at the cheaper end doesn't appear to result in any higher a resolution than 8.9"

Really I'd like something with built in 3G/HSDPA, but only the Dell Inspiron Mini 9 seems to have this, and the Linux model isn't even on sale yet in the UK, let alone the 3G version.

If I can't get 3G then I'm drawn to the EEE 901. It seems to have the best battery life, has bluetooth and isn't too expensive (though at the higher end of what I'd want to pay for a 2nd machine). Plus it has the appeal that I should be able to walk into a shop and pick one up. Main drawback is that I've read the Ralink RT2860 wifi ain't great (and the driver isn't in mainline yet, though there is one kicking around). Any truth in this? Any other gotchas?

Thoughts, people? I've seen an MSI Wind in the flesh and it was a bit big. The Acer Aspire One looks nice enough, but not great battery life and no bluetooth. Any others I should be looking at instead of the 901? Must be easily available in the UK. I will, of course, be running Debian on it.

No so clever now, eh?

Sep 2, 2008 / 0 comments

I've been quite pleased with my evil Perl script that logs into my OpenID account and then uses the credentials to pull authorised LiveJournal feeds to local files, ready for Liferea to read. Except I keep breaking my OpenID stuff (because I haven't got round to putting the openid.server/delegate headers in the Movable Type index template) and not noticing. And the OpenID login works fine, but then LJ just doesn't auth me rather than erroring, so I see some posts but not friends locked stuff. Tonight I noticed. And discovered posts all the way back to before June.

So if I've missed some major event in your life in the past 3 months, sorry. And if you get comments from me on old posts in the next few days, this is why.

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