Flavio's blog

Smooth operator

Flavio — Mon, 16 Jun 2008 16:52:14 +0000

This Friday the 13th was special. I’m not in any way superstitious, mind you, but I wasn’t expecting anything out of the ordinary either. So imagine my pleasure when, rather than bad luck, I got an unexpected phone call: my new BMW F800GS was ready, registered and fueled, a whole week before the estimate I was given about two months ago. Not that I was fearing any significant delay from the Bayerische, but I’ve come to learn that such estimates are usually a bit optimistic… Between me and her stood only an unending pile of papers to sign and, of course, a sizable check.

Already a few hundred km on the odometer, unfortunately most of them under cloudy skies and even some light rain. Smooth is the keyword — smooth engine, smooth handling. Now if only the weather could get a little bit better…

A couple of reviews and in-depth descriptions for you:

from webBikeWorld
from American Motorcyclist

“He move in space with minimum waste and maximum joy…”

Euler’s identity

Flavio — Mon, 26 May 2008 20:50:28 +0000

Do you know the value of e^iπ (also known as Euler’s identity)?

iproute2: Linux kernel configuration

Flavio — Sun, 27 Jan 2008 19:57:37 +0000

Note to self: if you want to use iproute2, remember to enable CONFIG_IP_ADVANCED_ROUTER=y and related stuff in the kernel configuration.

If you don’t, the ip rule add command will answer “RTNETLINK answers: Operation not supported”.

Dear Apple

Flavio — Mon, 17 Sep 2007 09:22:40 +0000

Dear Apple,

I really love my iPod nano (1st gen). I also love Linux, but I’m told you don’t like the two things to live together. Fortunately, I’m also told that some good guys already worked around the protection, but still this really makes me wonder if I should keep buying your products; I didn’t know the story about DAAP and RAOP either. I’m not going to sell my nano outright, but why would I buy the new one if I can get the same functionality, minus the closeness, from my Nokia phone, for example? And I can also install any software I like on it.

Really. Your products are good. Your policy is not. Fix that, please.

Submitted this through Apple’s iPod feedback form, let’s see if I get an answer.

Defeating paranoid system administrators

Flavio — Sat, 24 Feb 2007 13:51:56 +0000

If a paranoid system administrator has blocked ssh access from Linux hosts to your office’s network — using the OpenBSD packet filter’s fingerprinting — and you find yourself without access to the office’s mail server, you might want to make your Linux workstation’s TCP stack look like something else by changing the TTL, for example:

echo 128 > /proc/sys/net/ipv4/ip_default_ttl

The road to this hack is quite easy, anyway:

install OpenBSD in a virtual machine;
look hard at /etc/pf.os and look for possible useful differences;
see that Linux uses a TTL of 64 while Windows XP uses 128;
profit!

Item 1 was needed because I couldn’t find a copy of /etc/pf.os quickly, so I figured that it’d take less to just install an OpenBSD.

Free as in “we decide which fonts you use”

Flavio — Wed, 14 Feb 2007 09:09:08 +0000

Yesterday I found an article on digital rights management on the GNU web site. The article itself is interesting, although IMHO a little bit too biased towards the “see how many freedoms they could take away from us” angle — but that’s the way RMS thinks. However, I was disappointed to see that the article — the entire www.gnu.org site, in fact — was using the Bitstream Vera Sans font. Here’s the relevant part from the style sheet, and note the comment:

font-family: "Bitstream Vera Sans", sans-serif; /* favour free fonts!! */

Now don’t get me wrong, I like the Bitstream Vera fonts just as much as you do and I use them extensively, not just because they’re free, but because they do indeed look quite good — at least on Linux. But I was reading that article from the office on a Windows XP machine and the Bitstream Vera fonts don’t look good there, or at least not as good as Verdana. Anyway, that’s not the real point: if one prefers a different font, perhaps just as free like Isabella, what can (s)he do?

The funny part is, Stallman’s own site (http://www.stallman.org) doesn’t force you to use free fonts…

Bookmarks-wiki

Flavio — Thu, 08 Feb 2007 16:14:26 +0000

Finally, I put my bookmarks in a wiki.

(of course, it’s not user-editable; not yet, at least)

One more reason to ditch Windows

Flavio — Tue, 05 Dec 2006 10:20:45 +0000

One of our programs wasn’t working when the input file was on a Linux server. You know, I make a living writing software on Windows, but I’m a Linux guy at hearth, so this was a bit disappointing. Initially, I blamed it on a misconfigured Samba, then I looked at the code and saw that it errored out on a call to tmpfile(). OK, let’s look at the documentation for tmpfile() in the Visual Studio help, just in case…

… The temporary file is created in the root directory. …

Say what?

No, really… WHAT?!?!?

Let’s put aside for a second the fact that any sensible administrator will never, ever allow write access to the root directory of a network volume. AFAIK, the root of the C: drive is read-only on Windows XP if you don’t have administrative rights, so this would break.

Users and servers

Flavio — Thu, 16 Nov 2006 11:09:45 +0000

When one of your users complains that your mail server “doesn’t work”, 90% of the times it’s his own fault, and 10% of the times it’s someone else’s fault. You’ll notice that 90% + 10% makes 100% of the cases. Actual problems on the server do happen sometimes, but the chances that your users notice before you do are basically zero.

You guessed it, today I got one too much of such “the server doesn’t work” complaints.

Xplanet for your desktop

Flavio — Mon, 16 Oct 2006 22:28:37 +0000

I’ve been using astronomy pictures as my desktop background for years. In a never-ending search for the perfect background, however, I’m now using an Xplanet-generated image of the Earth and the Moon, with the Veil nebula behind them as additional eyecandy. Click on the sample image for a larger version — but I’ll tell you how to generate your own.

If you’re using KDE like I do, some good soul already set up all the pieces for you: open the “Advanced Background Settings” window, click on “Use the following program for drawing the background:” and select “xplanet” from the list. You’ll probably want to tweak the options and maybe even the Xplanet configuration file. This is the command line I’m using:

xplanet -config desktop -latitude 30 -longitude 11 -radius 35 -glare 0.001 -base_magnitude 0 -background ~/pics/noao/veil_1280×1024_darkened.jpg -geometry %xx%y -num_times 1 -output %f.jpg && mv %f.jpg %f

I’m setting the Sun glare to 0.001 because the Sun passes just above the top of the picture at night and the glare would turn the background into a pale yellow splotch.

I’m setting the base magnitude to 0 because the background picture already provides all the stars I want. I scaled the background image to the right size and darkened it a little bit to get rid of the nebula’s faint diffuse glow and to reduce the amount of stars.

Here’s the important part of the configuration file:

[default]
max_radius_for_label=0 # never draw labels

[sun]
shade=100 # No night side!

[earth]
magnify=40

[moon]
magnify=40

The bodies are enlarged 40 times, otherwise you wouldn’t see the Earth and Moon in the same image very often.

Of course you’ll want to add color maps, a specular map and a bump map. For the image above I used maps from James Hastings-Trew’s Planetary Pixel Emporium. Note that I’m not using a bump map on the Moon because it would add too much detail.