May 25th, 2009
I got back this week-end from a nice week of rock climbing in Arco, Italy with Jeroen and Raimond. We stayed at Camping Arco, a really nice and fairly luxurious camping if you can manage to get a place there (they refuse reservations lasting less than 7 nights, or made less than two weeks in advance). The weather was perfect; in fact it was almost too warm for the time of year, and we skipped some of our planned activities because of that. Lessons learned for next year: go in April, and don’t climb south-facing walls in the middle of the day.
A couple of pictures, made by Jeroen or at least with his camera: Read the rest of this entry »
Tags: arco, climbing, italy, vacation
Posted in me, misc | 8 Comments »
May 15th, 2009
I installed Ubuntu 9.04 on a machine at work this week, and that went quite flawlessly except for one weird little problem. I could access machines on the local network by their short name (e.g. ‘einstein’) but not by their fully-qualified domain name (’einstein.intra.local’).
Now, if it had been the other way around, the explanation would have been obvious: a missing ‘search intra.local‘ entry in /etc/resolv.conf. But being able to resolve short names but not long ones, that was a new problem for me. I used nslookup to verify that the local name server was responding correctly to both forms, and it was. But any other application, from ping to Mozilla Firefox, failed to resolve the long form.
A colleague put me on the path to the solution, however. In the zeroconf protocol, which is implemented in Linux as Avahi and on the Mac as Bonjour, the .local domain is magic and is considered a reserved name. Hence, when Avahi is running, any address resolution queries for a machine name ending in .local, are intercepted and the DNS server never gets to see them (nslookup bypasses the usual resolver API, however).
This is apparently a known issue, but it was new and quite surprising to me. I didn’t bother to investigate who is at fault here: did the zeroconf people blatantly highjack a perfectly valid namespace, or has .local always been reserved and everybody but me knew about it? Anyway, it’s fair to assume that zeroconf is here to stay now, so network administrators take note: better call your local domain something else.
Once you know what it is, the solution is easy. In my case I wasn’t interested in the functionality offered by Avahi, so I just uninstalled it (sudo apt-get remove avahi-daemon). Alternatively, here is a receipt for disabling the special treatment of .local, but keeping the rest of the daemon running.
Tags: avahi, bonjour, dot-local, zeroconf
Posted in linux | 3 Comments »
February 11th, 2009
Why is it that, as you progress towards supposedly higher levels in your career, the trainings tend to get more infantile?
When I was just starting out as a programmer, most of the trainings I took were of course purely technical: how to operate a particular database system, how to write software for a particular operating system. The last time I received such a training was long ago, but I remember being generally treated as an adult. The trainer’s communication style would presuppose a certain amount of intelligence and common sense from the students, and we were assumed to be already familiar with the basics of software development until we demonstrated otherwise. Some trainers were better than others of course, but in general they were efficient and useful.
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Posted in misc | 1 Comment »
November 16th, 2008
The number 65,536 is an awkward figure to everyone except a hacker, who recognizes it more readily than his own mother’s date of birth
– Snow Crash, Neil Stephenson
A question which I like to use when interviewing C++ programmers: what is the range of a 32-bit integer?
I don’t use this question very often anymore, or at least I don’t let it influence my decision very much (which is why I don’t mind spilling the beans here), because the correlation with other technical skills turns out to be not as strong as I thought it would be. Still, there are some interesting patterns in the kind of people who know the answer versus those who do not.
Among the people who do not know the answer, some of them react quite affronted that they would even be expected to. What is the point, they will ask, in having memorized some little piece of trivia which they could Google up in a few seconds? Isn’t “knowing where to find it” a much more useful skill? Ask me about architecture! Ask me about design patterns and data structures! All of these objections have some validity, and indeed we will certainly ask about those other things during the interview. Still, I believe that it is perfectly reasonable to expect a good developer to know the answer to the above question by heart.
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Posted in hacks | 6 Comments »
July 24th, 2008
So I read on Slashdot today that Edward Davidson, the “Spam King” escaped from federal prison with the help of his wife.
(Update: it now turns out that after the escape, Mr. Davidson killed his wife and one of his children, and then committed suicide. This blog post, intended as a light-hearted tongue-in-cheek piece, was written before I learned of this. Kind of throws the whole thing in a different light.. Kids, please don’t become spammers — it really isn’t worth it.)
One obvious observation that can be made here is that, unless he is very certain that he will be able to evade justice for the remainder of his life, this was a pretty stupid thing to do: the punishment for escaping from prison is likely to be a lot harsher than the 21 months in minimum-security he received for his original crime.
Another question that came up in the /. comments is whether 21 months in minimum-security prison is an appropriate punishment for a spammer. Many people made the point that, although obnoxious, spamming is a non-violent crime and should therefore be treated less seriously than, say, murder.
I disagree.
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Posted in misc | 5 Comments »
June 22nd, 2008
With my subscription to XS4ALL, I received a Thomson Speedtouch 716 ADSL/Wifi router, currently running software release 6.1.9.6. Behind that router, I have a Linux server which serves as the webserver for the blog you’re reading right now, as well as my mailserver and a few other things. The Linux server also acts as a firewall for the rest of my network:
As you can see, the ADSL router and anything connected to it through the WiFi is considered untrusted: the real access point to my internal network is the Linux machine.
Among other things, the Speedtouch has the ability to support Voice-Over-IP by attaching an analog phone. Unfortunately, this functionality does not work in combination with the “assign public IP to a machine on the local network” setting. Which is a pity, because behind the router is my Linux server, running a web- and mailserver among other things, and I really want that server to have my public IP address. Partly because having the server NATted could cause problems with mail, in particular, in the sense that when I send out mail to another server, some suspicious spamblocker software may take offense if the address reported in the headers of my outgoing mail does not match my actual IP. But mostly because having a web/mail/FTP/whatever server hidden behind a NAT, just feels wrong.
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Posted in hacks, linux | 8 Comments »
April 16th, 2008
So, this Saturday, I jumped out of an airplane.
The jump was a birthday present for my father, who has always been very interested in everything related to planes. But of course, when we gave him the gift certificate, it went without saying that me and my brother would jump as well.
And it was COOL! All three of us loved it.
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Posted in me, misc | 2 Comments »
February 24th, 2008
My shiny new Nokia N810 Internet Tablet arrived this week, and I like it!
(Bias alert: my friend Dirk-Jan works for Nokia in Finland as a project manager on the N810, so that made me a little more interested in this gadget than I would otherwise have been.)
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Posted in cool-tool, linux | 11 Comments »