Just bought me an external flashlight; a Nikon Speedlight SB-900, which is Nikon's top model. It wasn't as expensive as that sounds, though, since this was their demo model that they got me a good discount on, on top of the already rather low prices that this shop offers; this made it cheaper than the list price of the SB-600, Nikon's second-best model. I'm afraid it will take a while before I'll be able to fully understand its features, though. I did get a course at photography when I was about 13 years old, which did help me in picking up again how to work with an SLR camera when I bought it. But that course never included anything about using flashlights; and while I do understand how bouncing light off of walls and other things may sometimes help in getting the picture just right, I haven't actually ever done that. So I guess I'll be practicing a bit, now...

I saw an article on Wired today: The Lost Tribes of RadioShack. It is well worth the read even if you re not into electronics. A key quote:

[H]is shop is a lone outpost; in a single generation, the American who built, repaired, and tinkered with technology has evolved into an entirely new species: the American who prefers to slip that technology out of his pocket and show off its killer apps. Once, we were makers. Now most of us are users.

I remember as a kid eagerly awaiting each year s new RadioShack catalog. I d read them pretty much cover to cover for fun. And who wouldn t? The catalogs had fun things like radios, telephone gadgets, calculators, tape recorders, electronic lab kits , books, components, LEDs I loved the catalogs and loved the store. My parents bought me a electronic kit (if memory serves 20 years later, it s the deluxe 160-project electronic kit from page 156 of the 1988 catalog, though it may have been purchased a different year). I had endless fun with that thing. It had resistors, diode, capacitors, oscillator, speaker, LED, relay, etc plenty to make a bunch of kid-friendly projects. Just looking at the catalog makes me excited even today. On the next page from the kit I had is a $5 crystal radio kit which needs no power source Solderless. With earphone, instructions, theory. On page 28 there was a revolving red light, and some microcassette recorders on p. 36 (I had one of those for awhile). I had enthusiasm for building and figuring out things for a long time. My dad let me take apart an old lawn mower for fun once I m sure he knew ahead of time it would never be back together. One of his friends from work built homemade contraptions out of things like an old vacuum cleaner (attach a cardboard tube to the exhaust and you get a great tennis ball shooter). And there was always all sorts of fun junk to discover up in the barn. I eventually shifted to a different sort of making things : programming. It has kept me busy for quite a number of years. But the Wired article has a point. RadioShack is struggling. Many people have no interest in making or fixing things anymore. The best-selling smartphone in the world comes sealed in a metal case where not even the battery can be replaced, the software is dictated by a company in California, and good luck trying to program for it without signing your life away first. A far cry from the first computer I used, a TRS-80 Color Computer II, bought, yes, at RadioShack. Turn it on, and in a few seconds you get a BASIC prompt. Can t really use it without programming. Being able to read its manual was an early motivation for me to work at learning to read. It is sad that so many devices can t be worked on anymore, and that so many people don t care. It is difficult for me to give Jacob (and later, Oliver) the sort of experience I had as a child. Companies would love to sell us $50 DVD sets, $300 educational game systems, $40 educational games, and any number of $30 plastic toys (some of which we have and the boys enjoy). I d rather give him a $10 bag of resistors, capacitors, wire, battery holders, LEDs, and a book, and see what he can come up with (when he s a bit older, of course). And, in fact, he and I built his first computer together. We installed the ultimate in operating systems for tinkering: Linux. This all brings me back to RadioShack. I ve been working on ham radio lately, with an eye to that being a project for Jacob (age 3.5), Oliver (just turned 1), and me to enjoy in the future. I needed some cable, and had been told by many people to visit the RadioShack in Derby, KS. It s like the one mentioned in the Wired article: huge, selling everything from washing machines to bulk cable, except this one specializes in amateur radio. I asked Jacob if he would like to come with me to a radio store. Dad, I would LOVE that! He brought his little semi-broken walkie-talkies with him to use during the hour drive there. At one point, he was concerned that a radio store is like a library and he might have to leave them on a shelf. I assured him he could keep them. We got to the RadioShack and he loved it. He couldn t even really contain his excitement. He ran back and forth along the bright green stripe running down the middle of the carpet. He excitedly watched them measure out 60ft of RG-8 coax for me. He pushed buttons on the demo clothes dryer, looked at all the antennas, and just had a great time. And he s been interested in my radio, too. When I was talking to somebody on it the other day, he said, I think he is at the radio store. He is having fun there. Right now, everybody I talk to on the radio is at the radio store to him. Jacob loves the fact that the backlight on my FT-857D can change colors, and often comes into the office just so I can put it into setup mode and let him spin the big wheel to change the colors. He enjoys opening boxes of components, and came out to help (and run around) while I suspended a dipole from some trees last Friday. I had told Jacob when we got to the store that This radio store is called RadioShack. He obviously took that to heart, because now if he hears me talking about a radio store , he will say, Dad, actually it is radio SHACK. So I say thank you to the Derby RadioShack for keeping the magic of making things with your dad alive for another generation.

My project. This post assumes that the reader has read my last post. This weekly report is late, because I was too interested in the project to stop working on it to write. Next week it have to be earlier, since I m going to New York on Sunday, and will have to take a time from the project. First of all, I need to say that I thought all problems were gone in my last post, but I noticed after a lot of testing that there is a segfault (or memory corruption or etc) that happens about one of five times I ran the real/maillist benchmark. I tried a lot of combinations of parameters to the RTS (-C0 -A4k -i0 -DS and others) to make it behave deterministically, and it did, without segfaults. I could not reproduce the segfault deterministically, because all of these parameters made the segfault disappear. My old debugging technique, of printing a log to see where the program has went before the segfault happened, also is causing the segfault to disappear, so this one is being much harder to debug than the last ones. I m still looking at it. In a moment of this week I thought of pulling the latests patches from GHC, which created the need of rebuilding the whole system. I probably rebuilt with a different mk/build.mk, so I got some very distorted benchmark results when comparing before executions from before this build and after them. Because this distortion only made itself visible in a benchmark where I ve introduced some improvements which I was very positive about, I naively thought that the -46% results were actually real. After a reasonable disbelief of my mentor, I remembered the complete rebuild and thought that was the cause. I reran the pre-rebuild benchmarks, and got the updated results. This whole week I kept on benchmarking. At first I was using my usual system, but I noticed some very unexpected results, so I decided to run them in single-user mode, running nothing in parallel. In this condition, I belive the distortions are minimized. I organized my changes in sequential patches to the repository, to make it easier to measure. It takes a long time to run nofib, specially gc/gc_bench. While I organized the code, I notice the segfault was gone. I don t know still what was causing it, but I m not worrying very much, since it s gone. I m planning to write a bigger report next week with the complete results of the benchmarks.

The cherry-pick command in git allows you to copy commits from one branch to another, one commit at a time. In order to copy more than one commit at once, you need a different approach.

Cherry-picking a single commitSay we have the following repository composed of three branches (master, feature1 and stable):

$ git tree --all
* d9484311 (HEAD, master) Delete test file
* 4d4a0da8 Add a test file
  * 5753515c (stable) Add a license
  * 4b95278e Add readme file
 /
  * a37658bd (feature1) Add fourth file
  * a7785c10 Add lines to 3rd file
  * 7f545188 Add third file
  * 2bca593b Add line to second file
  * 0c13e436 Add second file
 /
* d3199755 Add a line
* b58d925c Initial commit

The "git tree" command is an alias I defined in my ~/.gitconfig:

[alias]
tree = log --oneline --decorate --graph

To copy the license file (commit 5753515c) to the master branch then we simply need to run:

$ git checkout master
$ git cherry-pick 5753515c
Finished one cherry-pick.
[master 08ff7d4] Add a license
1 files changed, 676 insertions(+), 0 deletions(-)
create mode 100644 COPYING

and the repository now looks like this:

$ git tree --all
* 08ff7d4a4 (HEAD, master) Add a license
* d94843113 Delete test file
* 4d4a0da88 Add a test file
  * 5753515c (stable) Add a license
  * 4b95278e Add readme file
 /
  * a37658bd (feature1) Add fourth file
  * a7785c10 Add lines to 3rd file
  * 7f545188 Add third file
  * 2bca593b Add line to second file
  * 0c13e436 Add second file
 /
* d3199755 Add a line
* b58d925c Initial commit

Cherry-picking a range of commits
In order to only take the third file (commits a7785c10 and 7f545188) from the feature1 branch and add it to the stable branch, I could cherry-pick each commit separately, but there is a faster way if you need to cherry-pick a large range of commits.

First of all, let's create a new branch which ends on the last commit we want to cherry-pick:

$ git branch tempbranch a7785c10
$ git tree --all
* 08ff7d4a (HEAD, master) Add a license
* d9484311 Delete test file
* 4d4a0da8 Add a test file
  * 5753515c (stable) Add a license
  * 4b95278e Add readme file
 /
  * a37658bd (feature1) Add fourth file
  * a7785c10 (tempbranch) Add lines to 3rd file
  * 7f545188 Add third file
  * 2bca593b Add line to second file
  * 0c13e436 Add second file
 /
* d3199755 Add a line
* b58d925c Initial commit

Now we'll rebase that temporary branch on top of the stable branch:

$ git rebase --onto stable 7f545188^ tempbranch
First, rewinding head to replay your work on top of it...
Applying: Add third file
Applying: Add lines to 3rd file
$ git tree --all
* ec488677 (HEAD, tempbranch) Add lines to 3rd file
* a85e5281 Add third file
* 5753515c (stable) Add a license
* 4b95278e Add readme file
  * 08ff7d4a (master) Add a license
  * d9484311 Delete test file
  * 4d4a0da8 Add a test file
 /
  * a37658bd (feature1) Add fourth file
  * a7785c10 Add lines to 3rd file
  * 7f545188 Add third file
  * 2bca593b Add line to second file
  * 0c13e436 Add second file
 /
* d3199755 Add a line
* b58d925c Initial commit

All that's left to do is to make stable point to the top commit of tempbranch and delete the old branch:

$ git checkout stable
Switched to branch 'stable'
$ git reset --hard tempbranch
HEAD is now at ec48867 Add lines to 3rd file
$ git tree --all
* ec488677 (HEAD, tempbranch, stable) Add lines to 3rd file
* a85e5281 Add third file
* 5753515c Add a license
* 4b95278e Add readme file
  * 08ff7d4a (master) Add a license
  * d9484311 Delete test file
  * 4d4a0da8 Add a test file
 /
  * a37658bd (feature1) Add fourth file
  * a7785c10 Add lines to 3rd file
  * 7f545188 Add third file
  * 2bca593b Add line to second file
  * 0c13e436 Add second file
 /
* d3199755 Add a line
* b58d925c Initial commit
$ git branch -d tempbranch
Deleted branch tempbranch (was ec48867).

It would be nice to be able to do it without having to use a temporary branch, but it still beats cherry-picking everything manually.

Another approachAnother way to achieve this is to use the format-patch command to output patches for the commits you are interested in copying to another branch and then using the am command to apply them all to the target branch:

$ git format-patch 7f545188^..a7785c10
0001-Add-third-file.patch
0002-Add-lines-to-3rd-file.patch
$ git am *.patch

Update: looking forward to git 1.7.2According to a few people who were nice to point this out in a comment, version 1.7.2 of git, which is going to be released soon, will have support for this in cherry-pick:

git cherry-pick 7f545188^..a7785c10

Today I fulfilled my old dream --- I just created my first book! Here is how it looks like:

More images
here.

Here is the source code of the book: http://github.com/certik/theoretical-physics, the repository contains a branch 'master' with the code and 'gh-pages' with the generated html pages, that are hosted at github, at the url theoretical-physics.net.

Then I published the book at Lulu: http://www.lulu.com/product/hardcover/theoretical-physics-reference/11612144, I wanted a hardcover book, so I setup a project at Lulu, used some Lulu templates for the cover and that was it. Lulu's price for the book is $19.20 (166 black & white pages, hardcover), then I can set my own price and the rest of the money probably goes to me. I set the price to $20, because Lulu has free shipping for orders $20 or more. You can also download the pdf (for free) at the above link (or just use my git repository). So far this didn't cost me anything.

I have then ordered the book myself (just like anybody else would, at the above address) and it arrived today. It's a regular hardcover book. Beautiful, you can browse the pictures above. It smells deliciously (that you have to believe me). And all that it cost me was $19.20.

As for the contents itself, you can browse it online at theoretical-physics.net, essentially it's most of my physics notes, that I collected over the years. I'd like to treat books like software --- release early release often. This is my first release and I would call it beta. The main purpose of it was to see if everything goes through, how long it takes (the date inside the book is July 4, 2010, I created and ordered it on July 5, got the physical book on July 19) and what the quality is (excellent). I also wanted to see how the pages correspond to the pdf (you can see for yourself on the photos, click on the picasa link above).

Now I need to improve the first pages a bit, as well as the last pages, improve the index, write some foreword and so on. I also need to think how to better organize the contents itself and generally improve it. I also need to figure out some versioning scheme, so far this is version 0.1. I think I'll do edition 1, edition 2, edition 3, and so on. And whenever I feel that I have added enough new content, I'll just publish it as a new edition. So if you want to buy it, I suggest to wait for my 1.0 version, that will have the mentioned improvements.

It'd be also cool to have all the editions online somehow and create nice webpages for it (currently theoretical-physics.net points directly to the book html itself).

So far the book is just text. I still need to figure out how to handle pictures and also whether or not to use program examples (in Python, using sympy, scipy, etc.). So far I am inclining not to put there any program codes, as then I don't need to maintain them.

Overall I am very pleased with the quality, up to some minor issues that I mentioned above, everything else end up just fine. I think we have come a long way from the discovery of the printing press. Anybody can now create a book for free, and if you want to hold the hardcopy in your hands, it costs around $20. You don't need to order certain amounts of books, nor partner with some publisher etc. I think that's just awesome.

I ve just done some quick research on Digital Video Cameras for some relatives. It seems to me that the main feature that is necessary is Full HD (1920*1080) resolution as everyone seems to be getting 1920*1080 resolution monitors (getting smaller doesn t save enough money to be worth-while). Resolutions higher than 1920*1080 will probably available in affordable monitors in the next few years, so the ability of programs like mplayer to zoom videos will probably be required even for Full HD video soon. Saving maybe $300 on a video camera while getting a lower resolution doesn t seem like a good idea. The next feature is optical zoom, most cameras are advertised with features such as advanced zoom to try and trick customers, cameras which advertise 60* or better zoom often turn out to only have 20* zoom. I think that about 20* optical zoom should be considered the minimum, not that there is anything special about 20* zoom, it s just that there is a good range of cameras with better zoom capacity. Image stabilisation is a required feature, no-one can keep their hand perfectly steady and the typically a DVC only gets hand-held use most people who own them don t even own a tripod! Digital image stabilisation is apparently not nearly as good as optical image stabilisation, and image stabilisation that involves moving the CCD is apparently somewhere in between. Finally it s good to have the ability to take quality photos as few people will want to carry a Digital Camera and a Digital Video Camera. I did a search for DVCs on the web site of Ted s Camera store (a chain of camera stores in Australia that generally provide good service at a competitive price but not the cheapest price). The best of the Ted s options seems to be the Panasonic SD60 HD Video [1] which does 25* optical zoom, 1920*1080i video, 5 megapixel still photography, and optical image stabilisation it costs $750 from Ted s. The next best option seems to be the Sony Handycam HDR-CX110 HD [2] which does 25* optical zoom, 1920*1080i video, 3.1 megapixel 2048*1536 still photography, and digital image stabilisation. The Panasonic seems to be a better option due to having optical image stabilisation and a higher resolution for still photographs. It is also $750 from Ted s. Now there s the issue of how well the cameras work on Linux. A quick Google search indicated that the Sony cameras present themselves as USB card readers and can be mounted on a Linux system, I couldn t discover anything about the Panasonic. If I was going to buy one I would take my Netbook to the store and do a quick test. I don t have enough information to recommend either of those cameras, they may have some awful defects that are only apparent when you use them. But in terms of features they seem pretty good. The Panasonic SD60 HD Video should be a good benchmark when comparing cameras in the store. If nothing else the camera store staff seem to not be very helpful if asked generic questions such as which camera is best , but if asked questions such as how is this other camera better than the one I m looking at they can usually give good answers. If anyone has any other advice for purchasing a DVC then please let me know. Either generic advice or specific examples of Linux-friendly DVCs that have been purchased recently.

• [1] http://www.teds.com.au/panasonic-digital-video-cameras/panasonic-sd60-hd-video-50-bonus/w1/i6674617_2372546/
• [2] http://www.teds.com.au/sony-digital-video-cameras/sony-handycam-hdr-cx110-hd/w1/i6723301_2372492/

One thing I noticed having started to use gnash is that the BBC's iPlayer website (UK-only, I believe) gives a message like "You do not have Flash player installed" - not merely complaining about the version, but actually not recognising gnash as a Flash player at all. Cue some digging. The BBC's pages use glow, an in-house JavaScript library (available under the Apache 2.0 License) to detect whether Flash is installed. The documentation was really easy to follow - I had a test page going quicker than you can say "Hello, World!" The bottom line is, glow uses this regex:

var regexFLASH_VERSION = /^Shockwave Flash\s*(\d+)\.(\d+)\s*\w(\d+)$/;

and gnash uses a description like this:

Shockwave Flash 10.1 r999.
Gnash trunk, the GNU SWF Player. Copyright (C) 2006, 2007, 2008, 2009,
2010 Free Software Foundation, Inc.
Gnash comes with NO WARRANTY, to the extent permitted by law. You may
redistribute copies of Gnash under the terms of the GNU General Public
License. For more information about Gnash, see
http://www.gnu.org/software/gnash.
Compatible Shockwave Flash 10.1 r999.

Note the dollar sign at the end of the regex. Indeed, rebuilding gnash without all the notices at the end of the description lets you see the iPlayer UI. (It doesn't actually play anything, don't get your hopes up.) Interestingly, different parts of iPlayer require different minimum versions of Flash. Clips of radio programmes tend to be more liberal with what they will accept - right down to version 7. Most TV streams and clips require at least version "9.0 r115", and I've heard they use SWF verification. I'm not sure how legal it is to implement that, although apparently code exists.

As part of the 11th Debian Conference in New York City, USA, there will be OpenPGP (pgp/gpg) keysignings. If you intend to participate in the DebConf10 keysignings, please send your ascii armored public key as explained no later than Tuesday 20th of July, 2010 at 23:59 UTC. If your mail to anibal@debian.org cannot get through, send it to anibal at v7w dot com but first try the debian.org email address, please. More (and up-to-date) information is available so keep watching that page. An bal Monsalve Salazar and the DebConf team

Apparently Michael Widenius isn't quite about to give up on his quest against Oracle. The latest news is that he's appealing the EC decision. Wonder what the use of that is, since the merger seems pretty final already. I also don't think it's a very good cause, at any rate. After all, the worst that can happen is that MySQL will fork. Or that Oracle will pour some resources in it, and actually make it a database, rather than the POS toy it currently is. Or that it dies out, and that the world switches over to PostgreSQL or Firebird for Free Software database requirements. Wouldn't be a big loss, would it? Give up already, Monty!

On python stable APIs

There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened.

In Debian testing:

/usr/lib/python2.6/dist-packages/sqlalchemy/types.py:547: SADeprecationWarning: The Binary type has been renamed to LargeBinary.

In Debian Lenny:

ImportError: cannot import name LargeBinary

I was starting to think that SQLAlchemy wasn't too bad, since I've been using it for 6 months and I haven't seen its API change yet. But there it is, a beautiful reminder that SQLAlchemy, too, is part of the marvelously autistic Python ecosystem.

I got convinced to hold an IRC talk on usage of the Debian BTS in #ubuntu-classroom and thought it might be interested to other children distributions of Debian, too also for regular Debian users. So feel invited to attend it. It will be held in #ubuntu-classroom on irc.freenode.net on Thursday, 22nd of July, at 18:00 UTC. For those who have never attended such a session yet, you might want/need to also join #ubuntu-classroom-chat too and raise questions in there, the main channel will be set to moderated. I will try to cover basic usage like querying the web interface, reporting new bugs and also more deeper handling of bugs, including version tracking issues, and will try to address raised questions as good as possible. Hope the session will be helpful to some and be able to address some questions like why some bugs aren't getting archived even though they are closed for ages. :) IRC logs will be available for the convenience of those who can't make it. So long!

This week-end, I didn't work a lot on Debian stuff (mostly running and gardeing...) but still managed to finally take care of my pet package, the one I maintain since 2001, namely geneweb. The package suffered from a very longstanding RC bug that made it unusable on amd64 machines. I had to call for help Ocaml gurus and R mi Vanicat kindly provided a working patch. So, now, geneweb can be released and I won't have to ask for my pet package to be removed from testing. I even switched it to dh7 and "minimal" debian/rules file (something I planned to do at DC10 but finally turned out to be easy to do. That will be my last week-end of activity in Debian until DebConf10 as I'll be away for the upcoming week-end. So, for those of you who attend DC10, see you in NYC. I'll arrive on Wed 28th evening for part of Debcamp and I'll have the great pleasure to introduce my son Jean-Baptiste to the Debian world.

After a quite long string freeze and last minute efforts by translators, I finally stopped the clock on Sunday July 11th for D-I localization update meant for the release of the beta1 version of debian-installer for squeeze. We finally have 65 supported languages. In a final effort, Belarusian, Ukrainian, Hungarian, Tagalog, Kurdish, Croatian and Macedonian were "rescued" and completed enough for being included in the release. Unfortunately, I had to deactivate Wolof, Serbian and Welsh because of lack of activity. For Serbian, this is very infortunate as new translators indeed tried to contact me with updates, which I missed and discovered only after it wasn't possible to revert the change. Good news are that Serbian is now already reactivated for the next release and we will even have both the Cyrillic and Latin versions of it. The mass upload of D-I packages happened mostly on Sunday 12th (you probably noticed that if you follow debian-devel-changes). It is already possible to test what will be D-I beta1: just go to the D-I development web page, then choose to download the daily built netboot image. Boot it with "install mirror/suite=unstable". This is not *exactly* what beta1 will give as this will install unstable and not testing, for non D-I packages...but I think that, until D-I packages migrate to testing, this is the best way to test beta1. The next step in D-I release preparation should be the mass migration to testing of most udeb packages.

I wrote a while back about the "fun" Jo and I were having with her Acer Aspire One 751 netbook, a machine that was "blessed" with Intel's integrated GMA500 graphics. It was a PITA to set the machine up and the final installation of Ubuntu Jaunty was anything but reliable, locking up frequently. Well, there's more to the story. In the comments on that blog entry, Ben Armstrong pointed me at some very useful information from the Debian EeePC team: http://wiki.debian.org/DebianEeePC/Model/1101HA, specifically notes on how to use grub2 and the fbdev X driver to get native resolution on a 1366x768 screen. A couple of weeks back I finally managed to steal the laptop from Jo for a few minutes and try that setup. The results are very promising - X performance is perfectly acceptable and the X lockups have totally gone away. So (shock!) it looks like the crappy binary drivers were to blame. Jo is over the moon that finally her Linux laptop is happy and she has specifically asked me to blog again and thank Ben for his help. Thanks! I'm also hoping that this post will help other people searching for useful information on this nasty hardware and how to make it work as well as possible.

I spent the last two days at the BSP in Munich thanks to everyone for inviting & feeding me, & especially to Stefan for hosting me again!

Unfortunately the weather was not good enough for an excursion to a Biergarten but the local chefs at the LiMux office delighted us with self-made spaghetti salmone & self-rolled sushi, & we spent quite some time behind our laptops.

The main results can be seen on the wiki page; my personal conclusion is that the list of remaining RC bugs contains mostly "hard stuff" (e.g. architecture-, hardware-, or desktop-specific bugs). Probably some packages will need to be kicked out of squeeze & some bugs might get a squeeze-ignore tag ... To put it positively: I have a gut feeling that the freeze is getting closer :)

Thanks to todays opengeodata blog entry, I just discovered that the OpenStreetmap.org site have gotten support for calculating routes. The support is still experimental and only available from the development server, until more experience is gathered on the user interface and any scalability issues. Earlier, the routing I knew about using the OpenStreetmap.org data was provided by Cloudmade, but having it on the main page is required to make everyone aware of the issue. I've had people reject Openstreetmap.org as a viable alternative for them because the front page lacked routing support, and I hope their needs will be catered for when routing show up on the www.openstreetmap.org front page.

This is just a reminder that we will have a small bug squashing party in Berlin. It will take place on monday 19th july starting at 16:00 with open end in the rooms of B ro 2.0 in Neuk lln. You have to organize your accomodation by yourself if you do not live in Berlin. More information is available in the Debian Wiki. Please register there if you are planning to attend.

I just bought my tickets today to NYC and I am glady to say that I am going to Debconf 10. The tickets have this information:

• GRU->JFK: Departure: 2010-07-30, 21:25; Arrival: 2010-07-31, 6:10, Flight AA950
• JFK->GRU: Departure: 2010-08-09, 21:40; Arrival: 2010-08-10, 8:35, Flight AA951

This represents a personal milestone for me, as I have many plans for the conference. In fact, this will be a trip of many firsts for me:

• this will be my first international trip by airplaine.
• this will be my first DebConf ever (despite the fact that I could not apply for the DebConf Newbies initiative, due to my visa interview being delayed until the 7th of this month).
• this will be the first time to see many people with whom I work together for some years now, but have not yet had the opportunity to meet in person.
• this will be a nice opportunity to work hard on some issues that threaten the PowerPC port of Debian.
• this will be a nice opportunity to do some QA work with some packages that I would like to have sponsored; also to upload some of the fonts that I already packaged (or intend to take care) and that will be maintained under the Debian Fonts Task Force umbrella.
• this will be a very nice opportunity to get myself in a big strongly connected component of the Web-of-Trust with as many arcs as feasible, by means of the key signing party.
• and many, many other things that I would like to do for the project.

I am thankful for the DebConf team sponsoring both accomodation and food. It is highly appreciated. See you in NYC! Any hints that you may happen to have are warmly welcome.

This is a followup on my previous work on merging all the computer related LDAP objects in Debian Edu. As a step to try to see if it possible to merge the DNS and DHCP LDAP objects, I have had a look at how the packages pdns-backend-ldap and dhcp3-server-ldap in Debian use the LDAP server. The two implementations are quite different in how they use LDAP. To get this information, I started slapd with debugging enabled and dumped the debug output to a file to get the LDAP searches performed on a Debian Edu main-server. Here is a summary. powerdns Clues on how to set up PowerDNS to use a LDAP backend is available on the web. PowerDNS have two modes of operation using LDAP as its backend. One "strict" mode where the forward and reverse DNS lookups are done using the same LDAP objects, and a "tree" mode where the forward and reverse entries are in two different subtrees in LDAP with a structure based on the DNS names, as in tjener.intern and 2.2.0.10.in-addr.arpa. In tree mode, the server is set up to use a LDAP subtree as its base, and uses a "base" scoped search for the DNS name by adding "dc=tjener,dc=intern," to the base with a filter for "(associateddomain=tjener.intern)" for the forward entry and "dc=2,dc=2,dc=0,dc=10,dc=in-addr,dc=arpa," with a filter for "(associateddomain=2.2.0.10.in-addr.arpa)" for the reverse entry. For forward entries, it is looking for attributes named dnsttl, arecord, nsrecord, cnamerecord, soarecord, ptrrecord, hinforecord, mxrecord, txtrecord, rprecord, afsdbrecord, keyrecord, aaaarecord, locrecord, srvrecord, naptrrecord, kxrecord, certrecord, dsrecord, sshfprecord, ipseckeyrecord, rrsigrecord, nsecrecord, dnskeyrecord, dhcidrecord, spfrecord and modifytimestamp. For reverse entries it is looking for the attributes dnsttl, arecord, nsrecord, cnamerecord, soarecord, ptrrecord, hinforecord, mxrecord, txtrecord, rprecord, aaaarecord, locrecord, srvrecord, naptrrecord and modifytimestamp. The equivalent ldapsearch commands could look like this:

ldapsearch -h ldap \
  -b dc=tjener,dc=intern,ou=hosts,dc=skole,dc=skolelinux,dc=no \
  -s base -x '(associateddomain=tjener.intern)' dNSTTL aRecord nSRecord \
  cNAMERecord sOARecord pTRRecord hInfoRecord mXRecord tXTRecord \
  rPRecord aFSDBRecord KeyRecord aAAARecord lOCRecord sRVRecord \
  nAPTRRecord kXRecord certRecord dSRecord sSHFPRecord iPSecKeyRecord \
  rRSIGRecord nSECRecord dNSKeyRecord dHCIDRecord sPFRecord modifyTimestamp
ldapsearch -h ldap \
  -b dc=2,dc=2,dc=0,dc=10,dc=in-addr,dc=arpa,ou=hosts,dc=skole,dc=skolelinux,dc=no \
  -s base -x '(associateddomain=2.2.0.10.in-addr.arpa)'
  dnsttl, arecord, nsrecord, cnamerecord soarecord ptrrecord \
  hinforecord mxrecord txtrecord rprecord aaaarecord locrecord \
  srvrecord naptrrecord modifytimestamp

In Debian Edu/Lenny, the PowerDNS tree mode is used with ou=hosts,dc=skole,dc=skolelinux,dc=no as the base, and these are two example LDAP objects used there. In addition to these objects, the parent objects all th way up to ou=hosts,dc=skole,dc=skolelinux,dc=no also exist.

dn: dc=tjener,dc=intern,ou=hosts,dc=skole,dc=skolelinux,dc=no
objectclass: top
objectclass: dnsdomain
objectclass: domainrelatedobject
dc: tjener
arecord: 10.0.2.2
associateddomain: tjener.intern
dn: dc=2,dc=2,dc=0,dc=10,dc=in-addr,dc=arpa,ou=hosts,dc=skole,dc=skolelinux,dc=no
objectclass: top
objectclass: dnsdomain2
objectclass: domainrelatedobject
dc: 2
ptrrecord: tjener.intern
associateddomain: 2.2.0.10.in-addr.arpa

In strict mode, the server behaves differently. When looking for forward DNS entries, it is doing a "subtree" scoped search with the same base as in the tree mode for a object with filter "(associateddomain=tjener.intern)" and requests the attributes dnsttl, arecord, nsrecord, cnamerecord, soarecord, ptrrecord, hinforecord, mxrecord, txtrecord, rprecord, aaaarecord, locrecord, srvrecord, naptrrecord and modifytimestamp. For reverse entires it also do a subtree scoped search but this time the filter is "(arecord=10.0.2.2)" and the requested attributes are associateddomain, dnsttl and modifytimestamp. In short, in strict mode the objects with ptrrecord go away, and the arecord attribute in the forward object is used instead. The forward and reverse searches can be simulated using ldapsearch like this:

ldapsearch -h ldap -b ou=hosts,dc=skole,dc=skolelinux,dc=no -s sub -x \
  '(associateddomain=tjener.intern)' dNSTTL aRecord nSRecord \
  cNAMERecord sOARecord pTRRecord hInfoRecord mXRecord tXTRecord \
  rPRecord aFSDBRecord KeyRecord aAAARecord lOCRecord sRVRecord \
  nAPTRRecord kXRecord certRecord dSRecord sSHFPRecord iPSecKeyRecord \
  rRSIGRecord nSECRecord dNSKeyRecord dHCIDRecord sPFRecord modifyTimestamp
ldapsearch -h ldap -b ou=hosts,dc=skole,dc=skolelinux,dc=no -s sub -x \
  '(arecord=10.0.2.2)' associateddomain dnsttl modifytimestamp

In addition to the forward and reverse searches , there is also a search for SOA records, which behave similar to the forward and reverse lookups. A thing to note with the PowerDNS behaviour is that it do not specify any objectclass names, and instead look for the attributes it need to generate a DNS reply. This make it able to work with any objectclass that provide the needed attributes. The attributes are normally provided in the cosine (RFC 1274) and dnsdomain2 schemas. The latter is used for reverse entries like ptrrecord and recent DNS additions like aaaarecord and srvrecord. In Debian Edu, we have created DNS objects using the object classes dcobject (for dc), dnsdomain or dnsdomain2 (structural, for the DNS attributes) and domainrelatedobject (for associatedDomain). The use of structural object classes make it impossible to combine these classes with the object classes used by DHCP. There are other schemas that could be used too, for example the dnszone structural object class used by Gosa and bind-sdb for the DNS attributes combined with the domainrelatedobject object class, but in this case some unused attributes would have to be included as well (zonename and relativedomainname). My proposal for Debian Edu would be to switch PowerDNS to strict mode and not use any of the existing objectclasses (dnsdomain, dnsdomain2 and dnszone) when one want to combine the DNS information with DHCP information, and instead create a auxiliary object class defined something like this (using the attributes defined for dnsdomain and dnsdomain2 or dnszone):

objectclass ( some-oid NAME 'dnsDomainAux'
    SUP top
    AUXILIARY
    MAY ( ARecord $ MDRecord $ MXRecord $ NSRecord $ SOARecord $ CNAMERecord $
          DNSTTL $ DNSClass $ PTRRecord $ HINFORecord $ MINFORecord $
          TXTRecord $ SIGRecord $ KEYRecord $ AAAARecord $ LOCRecord $
          NXTRecord $ SRVRecord $ NAPTRRecord $ KXRecord $ CERTRecord $
          A6Record $ DNAMERecord
    ))

This will allow any object to become a DNS entry when combined with the domainrelatedobject object class, and allow any entity to include all the attributes PowerDNS wants. I've sent an email to the PowerDNS developers asking for their view on this schema and if they are interested in providing such schema with PowerDNS, and I hope my message will be accepted into their mailing list soon. ISC dhcp The DHCP server searches for specific objectclass and requests all the object attributes, and then uses the attributes it want. This make it harder to figure out exactly what attributes are used, but thanks to the working example in Debian Edu I can at least get an idea what is needed without having to read the source code. In the DHCP server configuration, the LDAP base to use and the search filter to use to locate the correct dhcpServer entity is stored. These are the relevant entries from /etc/dhcp3/dhcpd.conf:

ldap-base-dn "dc=skole,dc=skolelinux,dc=no";
ldap-dhcp-server-cn "dhcp";

The DHCP server uses this information to nest all the DHCP configuration it need. The cn "dhcp" is located using the given LDAP base and the filter "(&(objectClass=dhcpServer)(cn=dhcp))". The search result is this entry:

dn: cn=dhcp,dc=skole,dc=skolelinux,dc=no
cn: dhcp
objectClass: top
objectClass: dhcpServer
dhcpServiceDN: cn=DHCP Config,dc=skole,dc=skolelinux,dc=no

The content of the dhcpServiceDN attribute is next used to locate the subtree with DHCP configuration. The DHCP configuration subtree base is located using a base scope search with base "cn=DHCP Config,dc=skole,dc=skolelinux,dc=no" and filter "(&(objectClass=dhcpService)( (dhcpPrimaryDN=cn=dhcp,dc=skole,dc=skolelinux,dc=no)(dhcpSecondaryDN=cn=dhcp,dc=skole,dc=skolelinux,dc=no)))". The search result is this entry:

dn: cn=DHCP Config,dc=skole,dc=skolelinux,dc=no
cn: DHCP Config
objectClass: top
objectClass: dhcpService
objectClass: dhcpOptions
dhcpPrimaryDN: cn=dhcp, dc=skole,dc=skolelinux,dc=no
dhcpStatements: ddns-update-style none
dhcpStatements: authoritative
dhcpOption: smtp-server code 69 = array of ip-address
dhcpOption: www-server code 72 = array of ip-address
dhcpOption: wpad-url code 252 = text

Next, the entire subtree is processed, one level at the time. When all the DHCP configuration is loaded, it is ready to receive requests. The subtree in Debian Edu contain objects with object classes top/dhcpService/dhcpOptions, top/dhcpSharedNetwork/dhcpOptions, top/dhcpSubnet, top/dhcpGroup and top/dhcpHost. These provide options and information about netmasks, dynamic range etc. Leaving out the details here because it is not relevant for the focus of my investigation, which is to see if it is possible to merge dns and dhcp related computer objects. When a DHCP request come in, LDAP is searched for the MAC address of the client (00:00:00:00:00:00 in this example), using a subtree scoped search with "cn=DHCP Config,dc=skole,dc=skolelinux,dc=no" as the base and "(&(objectClass=dhcpHost)(dhcpHWAddress=ethernet 00:00:00:00:00:00))" as the filter. This is what a host object look like:

dn: cn=hostname,cn=group1,cn=THINCLIENTS,cn=DHCP Config,dc=skole,dc=skolelinux,dc=no
cn: hostname
objectClass: top
objectClass: dhcpHost
dhcpHWAddress: ethernet 00:00:00:00:00:00
dhcpStatements: fixed-address hostname

There is less flexiblity in the way LDAP searches are done here. The object classes need to have fixed names, and the configuration need to be stored in a fairly specific LDAP structure. On the positive side, the invidiual dhcpHost entires can be anywhere without the DN pointed to by the dhcpServer entries. The latter should make it possible to group all host entries in a subtree next to the configuration entries, and this subtree can also be shared with the DNS server if the schema proposed above is combined with the dhcpHost structural object class. Conclusion The PowerDNS implementation seem to be very flexible when it come to which LDAP schemas to use. While its "tree" mode is rigid when it come to the the LDAP structure, the "strict" mode is very flexible, allowing DNS objects to be stored anywhere under the base cn specified in the configuration. The DHCP implementation on the other hand is very inflexible, both regarding which LDAP schemas to use and which LDAP structure to use. I guess one could implement ones own schema, as long as the objectclasses and attributes have the names used, but this do not really help when the DHCP subtree need to have a fairly fixed structure. Based on the observed behaviour, I suspect a LDAP structure like this might work for Debian Edu:

ou=services
  cn=machine-info (dhcpService) - dhcpServiceDN points here
    cn=dhcp (dhcpServer)
    cn=dhcp-internal (dhcpSharedNetwork/dhcpOptions)
      cn=10.0.2.0 (dhcpSubnet)
        cn=group1 (dhcpGroup/dhcpOptions)
    cn=dhcp-thinclients (dhcpSharedNetwork/dhcpOptions)
      cn=192.168.0.0 (dhcpSubnet)
        cn=group1 (dhcpGroup/dhcpOptions)
    ou=machines - PowerDNS base points here
      cn=hostname (dhcpHost/domainrelatedobject/dnsDomainAux)

This is not tested yet. If the DHCP server require the dhcpHost entries to be in the dhcpGroup subtrees, the entries can be stored there instead of a common machines subtree, and the PowerDNS base would have to be moved one level up to the machine-info subtree. The combined object under the machines subtree would look something like this:

dn: dc=hostname,ou=machines,cn=machine-info,dc=skole,dc=skolelinux,dc=no
dc: hostname
objectClass: top
objectClass: dhcpHost
objectclass: domainrelatedobject
objectclass: dnsDomainAux
associateddomain: hostname.intern
arecord: 10.11.12.13
dhcpHWAddress: ethernet 00:00:00:00:00:00
dhcpStatements: fixed-address hostname.intern

One could even add the LTSP configuration associated with a given machine, as long as the required attributes are available in a auxiliary object class.

Wow tonight was thrilling. It s hard to explain why, but it s pretty exciting to have a radio setup that is all wrong in so many ways work well enough for me to sit in my kitchen in Kansas and talk to someone in Indianapolis using only two-way HF radios. I recently passed my technician and general amateur radio exams. I ve been talking to some very nice people locally on the 2m band, which permits local (say, 100-200mi radius) communication. It s been fun, but Kansas is sparsely populated enough that sometimes there just isn t any activity. At all. Earlier this week, my Yaesu FT-857D and two antennas arrived. I tried it first on VHF, and had a nice chat with Kent (KB0RWI) a few miles away. But tonight was the big experiment. I bought a 20m dipole antenna. This is basically a 30-foot-long wire, connected to a balun and a coax feed line in the middle. You re supposed to put it at least 30 feet off the ground, and away from trees, houses, etc. You re supposed to have a nice RF ground for your transmitter, power supply, antenna tuner, and all that stuff. You re not supposed to just run the coax under that (until today, annoying) small hole in the seal under the kitchen storm door. You re supposed to have to have the correct connectors on your coax, instead of soldering an RG-8 PL-259 onto some RG-8X because you re new at this and didn t realize that you need to buy an adapter. And, I m really pretty sure that you re not supposed to have an aggressive outdoor cat complete with a full set of claws and teeth attack the coax RG-8X cable as it s being pulled through the grass. Fail to do any of these things, and the thing might not work well, or might not work at all, or for people that use old equipment, might burn out your radio or something. So anyway I got out the ladder today, and I got the antenna maybe 10-15 feet in the air. I have three trees in a row with the perfect separation to hang each end and the center balun from. So while Jacob went around playing with water and trying out the ladder on occasion (with my help), I used some string to hang the antenna. In the trees, not far from them. Near the house. Not 30ft off the ground. I strung the feed line into the house, set up all my equipment on our kitchen table, flipped the switch. And nothing. Just the occasional familiar whine while tuning. I tried the 20m band, then the 40m, then even 15, 12, and 10. No activity anywhere. So what was wrong? I improvised some grounding extracted the ground conductor from an old strip of AC house wiring, shoved it into the ground, and grounded the tuner and transmitter. No difference. I unplugged the coax, and tested it with my multimeter. It tested out OK. I plugged it back in and wiggled the connector. Turns out the connector isn t in great shape, but it had been working. I tried transmitting. The tuner made a whole bunch of alarming-sounding clicking noises (sounded like a symphony of relays), indicated SWR over 3, and the ammeter on my power supply went a bit nuts. Later I realized that I just wasn t giving the tuner enough time to tune up; with a few more seconds, it tuned up just fine on every frequency. (So yes, it was supposed to do that.) And, it turns out, that all I needed to do was wait a little while longer to hear some signals. Pretty soon I was finding stuff all over the 40m band. I heard a discussion from Chicago, another from Oklahoma City, some apparent broadcasters from Africa. I decided I would try and transmit. I was hearing one side of a discussion very clearly and decided I would wait for an opportunity to try to contact that person. I heard his callsign, K9RM. I looked it up, and realized he was near Indianapolis, where I had lived for awhile. Eventually he invited a station trying to get in to participate. And: KD0MJT (I announced my callsign, as a request to join the conversation) He said he only made out the 0, but eventually we were talking quite well. It was a brief conversation, but interesting; the person he was talking to was in Portland, and couldn t hear me (and I could barely hear him, but not loud enough to make out). That with no phone lines, no Internet provider needed, etc. And with a rig that is far from being at peak efficiency. I had no idea what to expect tonight and was surprised that just tossing an antenna up in a tree let me talk to someone in Indiana. That s 650 miles away. I wonder what I ll be able to do once I get things done the right way. This hobby is going to be fun. Many thanks to Mike_W for equipment suggestions, Kent and Dan from Newton ARC for encouragement and coming out to the house to test things, Kent for being my first ham radio contact ever (on 2m while I was using an old 1981 radio), Chuck (K9RM) for taking a few minutes to be my first HF contact, and my dad for helping plan out exterior wall penetration methods that will eliminate this coax under the kitchen door and lack of grounding business. Jacob, by the way, still loves his radios and is starting to take an interest in mine. It wouldn t shock me at all of he s one of these kids that gets his technician license in the 2nd grade or something. I think he and I can do this together for a long time.