Blog de jeandamiendurand

A quick note, that a lot of people already have done, but well I did not up to now: how to install a local DNS cache. The culprit: I know nothing about that, but wants to speed up lookups that usually go via my ISP name servers.

Previously I had a linksys AP that was running dnscache by default. That was great. And now I switched to a freebox router, and it does not seem to run such cache. Anyway having something local on the PC in addition will not hurt.

dnsmasq or bind9 makes that very easy, especially for those you know nothing about DNS config and so on. So let's go with bind9 - for dsnmasq you will find other good and small howtos:

apt-get install bind9

Then edit /etc/bind/named.conf.options and uncomment the forwarders section as follow:

options {
directory "/var/cache/bind";

// If there is a firewall between you and nameservers you want
// to talk to, you might need to uncomment the query-source
// directive below. Previous versions of BIND always asked
// questions using port 53, but BIND 8.1 and later use an unprivileged
// port by default.

// query-source address * port 53;

// If your ISP provided one or more IP addresses for stable
// nameservers, you probably want to use them as forwarders.
// Uncomment the following block, and insert the addresses replacing
// the all-0's placeholder.

forwarders {
212.27.54.252;
212.27.53.252;
};

auth-nxdomain no; # conform to RFC1035
listen-on-v6 { any; };
};

Note that 212.27.54.252 and 212.27.53.252 are the DNS of my provider, Free. Nothing prevents you to put other name servers, in particular if you know some that are much quicker than the ones of your ISP, put'em instead. Restart bind9. That's all.

Please note that the packages contains hooks so that:
- If you have bind9 running, your /etc/resolv.conf will contain 127.0.01 as name server
- If you stop bind9, and you are in DHCP mode, your ISP DNS's will become automagically the name servers in /etc/resolv.conf.

You can test if this is working by doing "dig" on a host that is "far away", twice. The dig output will say something like:

;; Query time: 585 msec

the first time, and something like

;; Query time: 6 msec

the second time - because it is in the cache.

Argh, my previous printer died with a mechanical problem, and I though I'd better buy something, not professional - no, a printer for normal use, and cheap. I choosed the Canon iP1700 printer.

And, well, no native driver for Linux/CUPS.

Fortunately, as indicated here at openprinting.org, the driver for the iP2200 would work. And hey! There are debian packages for it:

#
## Canon ip1700 (the ip2200 drivers works with it)
#
deb http://mambo.kuhp.kyoto-u.ac.jp/~takushi/debian ./

I installed them, changed two lines in the iP2200 ppd file:

% diff /usr/share/cups/model/canonip2200.orig.ppd /usr/share/cups/model/canonip2200.ppd
48,49c48,49
< *MaxMediaWidth: "612"
< *MaxMediaHeight: "1656"
---
> *MaxMediaWidth: "215"
> *MaxMediaHeight: "584"

and choosed explicitely this modified iP2200 ppd file in the CUPS configuration. Works.

I use to run linux kernel with patches - and I particularly like the beyond patchset. Although totally unneeded, I use to compile this patched kernel with almost everything (inside for some, as modules for the majority). That's why I thought it might be useful for you; here it is with some additional kernel modules, i386 platform:

#
## Kernel linux-beyond
#
deb http://jeandamiendurand.free.fr/debian/kernel sid main
deb-src http://jeandamiendurand.free.fr/debian/kernel sid main

I have to say that suspend2 worked on my old laptop (which is now broken, oups), and not on my current desktop. Don't know why, I never really investigated.

Anyway, this patchset rocks, thanks in particular to the ck patchset.

I rarelly use advanced functions of shells, things that are specific to them - so that my shell scripts should be shell independant as much as possible. But there is one thing that remains very shell dependant: the prompt. And having a beautiful prompt is an eye candy pleasure!

For that, Zsh shell seems to be the winner, although I did not looked too much in others. The fact is that, like many people, I choosed a shell years ago, and use it almost exclusively for interactive work.

So, about the prompt, I found some time ago the excellent Phil!'s ZSH Prompt. I modified it a little bit to be ACPI compliant and to not be aggressive for the filesystems (on AFS, for example, it can be important to cache the results of a find).

Here is my modified version, zsh_prompt, and two screenshots (click to enlarge them): one showing the prompt in action when you type in some commands, another one showing the difference between root and user prompts, and how it reacts when your current directory name is made of too much characters:

I know two AFS implementations on linux: openafs and arla.

Unfortunately, since quite a long time, arla has been discontinued on debian. Hopefully I maintain when I have time unsupported debian packages of it.

On 10-jan-2007, we had the pleasure to receive the announce of a new upstream version: arla-0.90.

I do not produce any arla module for the debian/unstable stock kernel, but of course the source module is provided so that you can do it yourself. Here are the lines to add to your /etc/apt/sources.list file to get arla for debian/unstable/i386 (the source of the module is for all architectures of course):

#
## Arla
#
deb http://jeandamiendurand.free.fr/debian/arla sid net
deb-src http://jeandamiendurand.free.fr/debian/arla sid net

I hope you already heard about colinux - a really great package allowing you to run natively the linux kernel under windows. Yes! the linux kernel patched whenever necessary and compiled for windows.

At home we often run Windows, and, until qemu could boot onto another partition with no change to your disk's MBR, from linux or windows (see its faq), the colinux package is a great way to run Linux under Windows.

Setting up colinux to run its kernel and use your existing linux partition is fairly easy, although I recommend that you have static IP addresses in your LAN - just that this makes life easier; and because configuring colinux is easier as well.

I am not going to take for me what has been already very well explained elsewhere, so please follow this tutorial on setting up colinux to use your existing Linux partition on Windows !

Btw, better a recent Linux kernel of course, i.e. I use colinux development snaphots (not from the daily builds - but the one with a high version assigned - you will find)

Why not - freemat 3.0 preview (svn trunk) is packaged...:

#
## Freemat and its Matio dependency
#
deb http://jeandamiendurand.free.fr/debian/freemat experimental math
deb-src http://jeandamiendurand.free.fr/debian/freemat experimental math
deb http://jeandamiendurand.free.fr/debian/freemat sid math
deb-src http://jeandamiendurand.free.fr/debian/freemat sid math

Have fun -;

--- 02.12.2006 ---

freemat is still somewhat experimental, I observe sometimes clear drawbacks, eating cpu and memory - especially for drawing routines like semilogy()... I will switch back to octave (that has octaviz and octplot and is ... STABLE!) Nevertheless don't worry if you happen to follow the svn packages on debian - I plan to not discontinue them - and to follow freemat very encouraging development.

I had the need for nonequispaced fourier transform, and found the great nfft source code. But not packaged in Debian!

So here it is:

#
## Nfft
#
deb http://jeandamiendurand.free.fr/debian/nfft sid math
deb-src http://jeandamiendurand.free.fr/debian/nfft sid math

Two packages are available: libnfft3 and libnfft3-dev. Developers will want to install the development package:

apt-get install libnfft3-dev

Any feedback appreciated.