zoltan's blog

Convert an 32bit int to array of char in C

2009-10-14T23:52:00.000-07:00

int main()
{
char d[5];
unsigned int a=-123456789;
// int to array of char
char* p= (char *)(&a);
for(int i=0; i <4; i++)
d[i] = *(p+i); // store the int in 'd'
d[5] = '\0'; // add end character
// array of char to int
int out;
p= (char *)(&out); // create a char pointer to the first byte of the int
for(int i=0; i <4; i++)
*(p+i)=d[i];
printf("%d\n",out);
return 0;
}

vim: Automatic replace of tabs with spaces

2009-09-11T01:00:00.000-07:00

Add the following lines to ~/.vimrc:

set tabstop=4
set expandtab

To convert the TAB-s to spaces in edited files use

:retab

Stream your soundcard using pulseaudio and Nokia N95

2009-06-15T21:33:00.000-07:00

This guide will briefly explain how to create a network music stream server using the sound actually played on your sound card. I use to find this trick especially useful when I m sitting on my balcony with my laptop and in the same I can stream Pandora web radio via WiFi into my home music system (for the great happiness of my neighbours).

What you will need:

1. A computer with network connection.
2. A mobile phone able to connect to your PC via network and with the ability to play network mp3 streams. (I have an N95 8G phone with installed player CorePlayer. )

Setup:

Install pavucontrol, vlc player and sox.
Get the name of your sound card monitor device. Run in terminal:

pactl list | grep -A2 'Source #' | grep 'Name: .*\.monitor$' | cut -d" " -f2

The command should return something like this:

alsa_output.pci_8086_293e_sound_card_0.monitor
Run pavucontrol from your terminal and in 'Input devices' set the 'Show' option to 'All devices' . Find the monitor device and make sure that it is not muted.
Configure your network for some IP. For example 192.168.2.2.
Start up some music in your favourite music player.
Now let's convert the output of the monitor device of your sound card to an mp3 stream. Run this in the terminal:

parec --device=alsa_output.pci_8086_293e_sound_card_0_alsa_playback_0.monitor --format=s16le --rate=44100 --channels=2 | sox --type raw -s2L --rate 44100 --channels 2 - --type wav - | cvlc -v - --sout '#transcode{vcodec=mp4v,acodec=mp3,vb=800,ab=128}:standard{access=http,mux=raw,dst=192.168.2.2:8080}'

where pci_8086_293e_sound_card_0_alsa_playback_0.monitor is the name of your monitor device and 192.168.2.2:8080 is your PC's IP address with the streaming port. Yes, it looks freaky.
Connect your audio input of your mobile phone to your home audio system and play the 192.168.2.2:8080 stream in your mobile. With
few seconds delay you should hear the output of your PC's sound monitor device.

Good bye Ubuntu

2009-06-14T05:58:00.000-07:00

After four years on Ubuntu (my first install was Hoary) I decided to install Fedora 11 and say goodbye to Ubuntu. The reason is simple, the latest release Jaunty is simply an alpha software. I think I have quite solid knowledge to hack and usually get working all the X, WLAN and audio problems but Jaunty is simply too much pain. Good bye Ubuntu.

Resize images using ImageMagick

2009-03-18T22:55:00.000-07:00

Easy and fast way to batch resize of images using ImageMagick:

mogrify -resize 1200 *.jpg

Respectively:

mogrify -resize 800x600 *.jpg

Be careful! The original files will be overwritten!

Windows version of Firefox in wine vs. Linux version of Firefox

2008-11-20T02:17:00.000-08:00

I compared the firefox 3.0.4 windows version (under wine 1.1.4) and the Linux version of firefox 3.0.4. The result is surprising: the windows version runs faster under wine than the native Linux Firefox under Ubuntu.
While the windows version running in wine reacts on window zoom immediately, the Linux version spends 1-2 seconds on this operation ( core 2 duo 2GHz CPU).

Running the online javascript benchmark:

http://celtickane.com/webdesign/jsspeed.php

the windows also outperforms the Linux one.

I m disappointed. I think this can be a deal breaker for the new Linux users.

Encrypt directories using encfs

2008-08-24T10:19:00.000-07:00

This is a short guide about how to create encrypted directories under Ubuntu Linux.

Install EncFS:
sudo apt-get install encfs
EncFS uses the fuse kernel extension, which we need to load into the kernel
sudo sh -c "echo fuse >> /etc/modules" sudo modprobe fuse
Add yourself into the fuse group
sudo addgroup my_login_name fuse
Log out and log in.
Create your encrypted directory:
cd ~ mkdir .encrypt mkdir encrypt encfs $HOME/.encrypt $HOME/encrypt
Press enter few times, and chose a password.
Voala! The encrypted data will be stored in ~/.encrypt directory and it will be readable/writable trough the ~/encrypt directory. We used the $HOME parameter because encfs requires a full path to the directories. The password can be changed anytime using the encfsctl command.

Working Xorg.conf for Amilo v2030 using openchrome driver

2008-06-21T03:19:00.000-07:00

This settings should work for the openchrome driver on Siemens V2030.
I also recompiled the openchrome driver from the actual CVS tree.



/etc/X11/Xorg.conf

Section "InputDevice"
Identifier    "Generic Keyboard"
Driver        "kbd"
Option        "XkbRules"    "xorg"
Option        "XkbModel"    "pc105"
Option        "XkbLayout"    "us"
EndSection

Section "InputDevice"
Identifier    "Configured Mouse"
Driver        "mouse"
Option        "CorePointer"
EndSection

Section "InputDevice"
Identifier    "Synaptics Touchpad"
Driver        "synaptics"
Option        "SendCoreEvents"    "true"
Option        "Device"        "/dev/psaux"
Option        "Protocol"        "auto-dev"
Option        "HorizEdgeScroll"    "0"
EndSection

Section "Device"
Identifier      "Generic Video Card"
Driver          "openchrome"
EndSection

Section "Monitor"
Identifier      "Generic Monitor"
Option          "DPMS"
HorizSync       28-81
VertRefresh     56-75
EndSection

Section "Screen"
Identifier      "Default Screen"
Device          "Generic Video Card"
Monitor         "Generic Monitor"
DefaultDepth    16
SubSection "Display"
  Depth       16
  Modes       "1024x768" "800x600" "640x480"
EndSubSection
EndSection

Section "ServerLayout"
Identifier      "Default Layout"
Screen          "Default Screen"
InputDevice     "Generic Keyboard"
InputDevice     "Configured Mouse"
EndSection

I have 14 words for you

2008-06-11T09:36:00.000-07:00

Developers! Developers! Developers! Developers! Developers!
Developers! Developers! Developers! Developers! Developers!
Developers! Developers! Developers! Developers!

Download in MP3 and increase your coding speed by 120% !

openMosix dead(), LinuxPMI alive()!

2008-05-29T06:06:00.000-07:00

The openMosix project was officially closed in March 1., 2008. The patient cluster hobbyist and academicians were awaiting for the stable 2.6 kernel port of openMosix for several years. A small group of developers decided to pick up the project and continue the development under a new name LinuxPMI (Linux Process Migration Infrastructure). Will LinuxPMI ever deliver a stable 2.6 port? One thing is sure, LinuxPMI needs skilled kernel hackers and public recognition, that single-system image clustering should be the future of computing.

Not so frequent command line hacks

2008-05-10T08:25:00.000-07:00

Read which processes are writing to the hard drive

# echo 1 | sudo tee /proc/sys/vm/block_dump

wait few seconds

# echo 0 | sudo tee /proc/sys/vm/block_dump

# dmesg | grep WRITE
Detect service and server versions using nmap:

# nmap -A -T4 -F 192.168.1.1
Print the detailed statistics of transferred bytes by the firewall rules

# sudo iptables -L -nv
Convert the bit rate of an MP3

# lame -b 128 input.mp3 output.mp3
Setup wireless network from command line:

# sudo iwconfig wlan0 essid MY_AP_ESSID
# sudo iwconfig wlan0 key "12371272BCBCBABC1212"
# sudo dhclient wlan0

where wlan0 is the ID of network device.
Which process is accessing the CDROM

# lsof -n | grep /media/cdrom
Convert DOS end of line to UNIX end of line

# sed -e 's/\r$//' inputfile > outputfile

or

# tr '\r' '\n' < inputfile > outputfile
Get the size of a directory

# du -sh /home/blabla
Change MAC address of a network interface

# sudo ifconfig wlan0 hw ether AA:AA:BB:BB:CC:DD
Change your password in a non-interactive shell (PHP, Python web shells). Edit and paste these lines in to your shell:

passwd <<+++
oldpasswd
newpasswd
newpasswd
+++

Detect NAT using browser identification

2008-05-06T04:38:00.000-07:00

There are several workarounds how to detect a NAT in your network. Here I propose a simple (but not so accurate) solution based on the identification of User-Agent strings in HTTP packets.
The method is based on the assumption that there is a high probability that the users behind
of NAT are using different browsers or different version of the same browser.

We use tcpdum to capture and extract the User-Agent strings from the HTTP packets sent from the IP address 192.168.0.12:


tcpdump -s 4000 -vvv -xX -l -w- 'host 192.168.0.12 and tcp port 80' | strings | grep User-Agent

Example output:


User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; hu; rv:1.8.1.14) Gecko/20080404 Firefox/2.0.0.14
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; cs-CZ; rv:1.7.13) Gecko/20060414
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; sk; rv:1.8.1.14) Gecko/20080404 Firefox/2.0.0.14

You can see that from the same IP address we captured three different browser agent strings identifying at least three users behind of the given address.

How to periodically remove temporary files in Linux

2008-03-25T03:34:00.000-07:00

To remove periodically some files from a specific directory you can easily setup a cron entry. Execute in shell


crontab -e

and add


*/60 * * * * find  /home/my_home/some_dir/ -name '*.dat' -mmin +60 -exec rm {} \;

where .dat is the suffix of the files and "-mmin +60 -exec rm {}" is the option telling to remove the files with data modified more than 60 minutes ago.

If your crontab uses Vim for editing use :wq to save you changes and "INSERT", "ESC" to switch between Insert and Normal mode.

How to background image in LaTeX

2008-03-02T22:59:00.000-08:00

Add this code before
the \begin{document} part

\usepackage{eso-pic}
\newcommand\BackgroundPic{
\put(0,0){
\parbox[b][\paperheight]{\paperwidth}{%
\vfill
\centering
\includegraphics[width=\paperwidth,height=\paperheight,
               keepaspectratio]{background.png}%
\vfill
}}}

and this one right following the \begin{document} :


\AddToShipoutPicture{\BackgroundPic}

The name of background image is background.png.

Download web pages recursively with wget

2008-02-22T22:11:00.001-08:00

Execute in shell
wget -rk "http://wwwthis.com"

Simple user activity monitoring script for openMosix

2008-02-22T21:56:00.000-08:00

This simple script calculates the number of active CPUs in an openMosix cluster and the amount of resources used by the particular user. Copy it to your "/usr/local/bin/" folder and add it to your global bashrc file. The script works with the latest stable 2.4.26 openMosix and it was tested on Gentoo Linux.

Live free() or die()

How to create a histogram using awk

2008-02-14T00:20:00.000-08:00

Command:

awk ' NF > 0{ counts[$0] = counts[$0] + 1; } END { for (word in counts) print word, counts[word]; }' FILE.DAT

Example:
FILE.DAT
--------
A
B
C
A
B
B

The result:
A 2
B 3
C 1

Animated computer simulation of in vitro cancer growth

2008-02-06T14:35:00.000-08:00

On the next video sequences you can see the result of three state of the art models of cancer growth.

Spheric growth and the formation of necrotic core

Mitosis of cancer cells

Fractal growth of two neighboring cancer cell colonies

The author of computer simulations: Denis Horvath

How to userspace l7 filter on Ubuntu

2008-02-01T07:50:00.000-08:00

L7-filter is a classifier for Linux's Netfilter that identifies packets based on application layer data. It can classify packets as Kazaa, HTTP, Jabber, Citrix, Bittorrent, FTP, Gnucleus, eDonkey2000, etc., regardless of port. It complements existing classifiers that match on IP address, port numbers and so on. L7 filter is usefull if you want to limit or monitor different network protocols in your network. This article assumes that you have the basic knowledge how to use the terminal and set up a linux router.

This how to describes the step by step installation of Userspace L7 filter on Ubuntu Linux.

Installation

1. Method:

Add my PPA to you repository

deb http://ppa.launchpad.net/kuscsik/ubuntu hardy main
deb-src http://ppa.launchpad.net/kuscsik/ubuntu hardy main

and install l7-filter-userspace l7-protocols

2. Method:

Add the universe repositories to your sources list.
Install some necessary packages
sudo apt-get install g++ build-essential sudo apt-get install libnetfilter-conntrack-dev libnetfilter-conntrack1 libnetfilter-queue-dev libnetfilter-queue1
Download the source package of userspace l7 filter and the archive of the protocol definitions.
Unpack the protocol definitions and install it by

sudo make install
Unpack the userspace l7 filter, compile and install it
# tar -xzf l7-filter-userspace-v0.10.tar.gz # cd l7-filter-userspace-v0.10/
Download this patch # wget http://kuscsik.com/download/patch_l7_Zoltan_Kuscsik.patch # cdl7-filter-userspace-v0.10# patch -p1 < ../patch_l7_Zoltan_Kuscsik.patch
# /configure # make
Load a necessary kernel module and add to the automatically loaded modules
# sudo modprobe ip_conntrack_netlink # sudo bash -c "echo ip_conntrack_netlink >> /etc/modules"

Testing

Let assume that you have a Ubuntu server with two network devices with WAN device eth0 and LAN device eth1. With iptables we redirect forwarded packages to the userspace


# sudo iptables -A FORWARD -j NFQUEUE --queue-num 0

Create a l7 config file in your favorite editor


sudo vi /etc/l7_filter.conf

and add some protocols


ssh          5
bittorrent   6

The list of all supported protocols can be found here. From the config we can read that l7 filter will assign the mark 5 to the packets of ssh protocol and it will sign with mark 6 the bittorrent packets.

Start l7 filter in debuging mode

l7-filter -vv -f /etc/l7_filter.conf

On your LAN client run a bittorrent session or make an ssh connection to an external server. If everything goes fine l7-filter will recognize your traffic and inform you trough the standard output.

Usage

Now, we are able to mark the connections. The next step is to set up the traffic control. For this you can use the HTB packet sheduller.
[to be improved...]

You can set up the start of l7-filter automatically by adding a line to /etc/rc.local


nohup /usr/local/bin/l7-filter -f /etc/l7-filter.conf &

Warning! This is a dangerous solution on a production server. If the program terminates unexpectedly your users will be cut off from the internet. You should set up some kind of monitoring for the l7-filter process.
You will notice, that the filter uses significant amount of system resources. You can save some computation time and memory by improving the forwarding rule.
For example, if you plan to shape the outgoing peer-to-peer connections it is a good idea to add some port specific selection to the userspace redirection rule

sudo iptables -A FORWARD -i eth0 -p tcp --dport 1024: -j NFQUEUE --queue-num 0

which will pass to the filter only the packets targeting higher ports than 1024.

I will improve this article, so please subscribe to the feed. If
you have any question or comments don't hesitate to drop me a message.

Please read the home page of Layer 7 Userspace

http://l7-filter.sourceforge.net/HOWTO-userspace

Especially the section why it is a bad idea to use the packet filtering for service blocking.

IX webhosting: the default backdoor

2008-01-30T14:24:00.000-08:00

IX webhosting offers a very solid product for a reasonable price. Using cPanel it allows an easy administration of services and domains. You can choose between Linux or Windows hosting and with single clicks you can quickly install many of the available web applications. In the first days, I was very happy, that after the infinite number of manual installation of applications on the university servers I don't need to care about mail and mysql servers.

However, the answer for my first bug report was interesting:

Question:

" - Using phpshell and runing the chsh program on server side
the users are able to change their default shell from /bin/nologin to any other shell and get
access to the IX servers by ssh.
I hope my effort to inform you about the flaw will you not understand as a malicious activity. "

The answer:

" - Although pointing out that minor security flaw wasn't viewed as malicious activity, please understand that any other attempts to hack into our system will be viewed as such, and it will be treated according to our policies. Thank you very much for understanding."

Nothing serious. It is not so interesting to be publish on a blog. The bug was fixed and someone in the deep universe realized that pam.d in the /etc directory is not the short of PAMpers Discount.

Today I reported my second bug:

The default installation of IX's "click and install" E-commerce software allows read and write rights to users directory to anyone on the internet.
Probably you have lot of affected users.

No state of the art hacking needed. There is a nice php admin interface without password. OK, I know what is in your mind: You will notice at the first login that nobody asked your admin password. The trap is that the admin interface is linked only in to the cPanel and when you access it you have the feeling that the password authentication is missing because the authentication is derived from your cPanel access (as in many other applications and settings in cPanel). After all, a hacker can easily upload a malicious php file and execute some nice exec() calls affecting the rest of your domains hosted by IX webhosting.

The response of the hosting service was simple with showing the signs of deep philosophical understanding of basic forces governing the universe

"If you don't like it, don't use our Easy Install products."

and some more words about that they will not change the security policy.

....end of discussions ....

Conclusion:
If you are using the osCommerce product at IX webhosting check if you are able to login without password at www.your_domain.com/admin and if it necessary secure your site by setting up a .htpasswd file (google for how-to).

List directories only using ls

2008-01-29T06:59:00.000-08:00

Very basic and useful command


ls -d */

Transparent proxy with Squid 3 on Ubuntu server

2008-01-27T11:53:00.000-08:00

This is a short guide how to set up a transparent cache proxy on Ubuntu Server. Basically, there are two reasons why you may be interested setting up a Squid proxy: speed up your web access and save your bandwidth. Let assume that you already set up a Linux gateway using iptables. It is possible to run squid also on Windows but unfortunately it is extremely hard to find a hardware on which Windows is able to survive more than one week. Other words, windows is out of scope of this article.
The first step is to install squid 3


apt-get install squid3

edit the squid 3 configuration file in your favorite editor


sudo vi /etc/squid3/squid.conf

and set the transparency and the allowed hosts



http_port 3128 transparent
acl our_networks src 192.168.0.0/24

acl localnet src 127.0.0.1/255.255.255.255

http_access allow our_networks

http_access allow localnet

where 192.168.0.0/24 is the IP range of local network. Probably you need adjust the swap size


cache_dir ufs /var/spool/squid3 7000 16 256

where the first number denotes the size of cache in megabytes. Save you changes and restart the squid proxy by


sudo /etc/init.d/squid3 restart

For more detailed configuration read the manual of Squid or check the configuration examples on Squid wiki page.
Remember, the memory and processor usage of squid is a function of swap size.
Last but not the least we need to redirect the HTTP traffic to your new shiny proxy


iptables -t nat -A PREROUTING -i eth1 -p tcp -m tcp --dport 80 -j DNAT --to-destination 192.168.0.1:3128
iptables -t nat -A PREROUTING -i eth0 -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 3128

where eth1, eth0 are the LAN, WAN devices and 192.168.0.1 is the IP address of your LAN device.

After all, probably you feel the need to monitor the performance of your proxy. Unfortunately, most of the squid log parsers in the Ubuntu repository are configured for Squid 2.x. Nevertheless, squid 3 uses the same log format, so you can change the log file path in your parser config file (sarg, calamaris, etd.) or simply link the log directory of squid 3 to the correct path


ln -s /var/log/squid3 /var/log/squid

Good luck!

How to jailbreak the 1.1.3 iphone firmware

2008-01-24T15:25:00.000-08:00

According to Nate True's blog it is possible to jailbreak an 1.1.3 version iphone.

The steps are the following:

- Start with a 1.1.1 or 1.1.2 jailbroken phone with Installer.app installed.
- Plug in your phone via USB to your computer.
- Download, extract, and run iBrickr Special 1.1.3 jailbreak edition (ibrickr.exe in the archive).
- iBrickr will determine what firmware you are running on your phone and make sure you can run the update.
- iBrickr will then guide you through the process of obtaining and modifying the 1.1.3 firmware (make sure to read everything thoroughly).
- iBrickr will upload the new firmware image to your phone. Note that this only puts the file on your phone and does not modify it at all, yet.
- When iBrickr finishes (should take about 10 minutes), it will tell you to go to Installer and install the "1.1.3 soft upgrade" package. Do that.
- When the installer finishes (this should take another 10-15 minutes), your phone should reboot with a fresh activated 1.1.3 firmware.

Anyway, watch the source blog for new informations:

http://cre.ations.net/blog/post/iphone-113-jailbreak-released

How to benchmark C++ code using gcc and gprof

2007-08-28T07:54:00.000-07:00

As the last step of software development you should test the performance of your code. This is a simple example how to benchmark the time consumption of different procedures in a C or C++ code. We will compare two procedures: calculating sin and exponential values for 5e7 numbers. Let write a code with name test.cpp

#include
#define LIMIT 50000000
void exponential(){
double a;
for(int i=1; i != LIMIT; i++)
a=exp(i/1000.0);
}
void sinFunc(){
double a;
for(int i=1; i != LIMIT; i++)
a=sin(i/1000.0);
}
int main(){
exponential();
sinFunc();
return 0;
}

and compile by g++:

g++ -pg test.cpp -o test.out

After running the ./test.out file a new file gmon.out will appear in your working directory. This file contains the profile information of your code. This information can be read by running the command

gprof test.out

which will tell us:
Flat profile:
Each sample counts as 0.01 seconds.
% cumulative self self total
time seconds seconds calls s/call s/call name
51.66 1.17 1.17 1 1.17 1.17 sinus()
48.99 2.27 1.11 1 1.11 1.11 exponential()

that our program 51.6% of time spent for calculation of sinus() procedure and 48.99% for exponential().

Automatic upload to a ftp server (ubuntu)

2007-07-04T05:23:00.000-07:00

Install ncftp2


apt-get install ncftp2

and run


ncftpput  -p my_password -u my_user_name -C ftp.my_server.com \
 file_to_copy.ogg /file_name_on_ftp.ogg

For automatic upload in every hour edit cron by


crontab -e

and add this line


0   * * * * ncftpput  -p my_password -u my_user_name -C ftp.my_server.com  file_to_copy.ogg

3D CA library

2007-07-04T00:02:00.000-07:00

Peter wrote a nice library for 3D cellular automaton (CA). There are many useful tricks inside how to write a memory and speed efficient CA code.

Enemy territory nexus cheater list

2007-06-28T15:26:00.000-07:00

For one of the ET server owner I made a one month monitoring of the Nexus IRC logs.
Here you can find a nearly complete list of nexus cheaters.

Edit eps on linux

2007-06-25T16:07:00.000-07:00

There are many tools for converting between the formates eps, pdf, ps and latex but unfortunately
there are not supported by the most of open source vector graphics programs.
Our first task is to convert the eps file in to the native format of skencil. For this we will use the pstoedit program (standard package in most of distributions).


pstoedit -dt  -f sk my_file.eps my_file.sk

The -dt flag is very important, which will convert the postscript fonts to polygons.

Now, we need a second program called "skconvert" included in the skencil package. If it is not included as standard package in your Linux distro, you can download it from here
After the installation you are ready to convert the sk file to svg


skconvert my_file.sk my_file.svg

The resulted svg file can be now easily imported by Xara or Inkscape .

Here is a nice poster created by this technique.

"Structurally dynamic spin market networks" [5MB]

The resulted graphics is a combination of latex, eps and svg graphics.

Pstoedit may have problems with some of the EPS files. The solution is to convert those files to a Level 1 EPS (thanks to cengiz for this useful comment):


eps2eps -dLanguageLevel=1 input.eps output.eps

Another solution of EPS editing is to convert the EPS to a PDF file using epstopdf. The big news that PDF can be imported as a vector graphics by Inkscape 0.46 which is already included in Ubuntu Hardy Heron Beta release.

FOR ONLINE EPS2SVG CONVERSION VISIT: eps2svg.info

How to install Intel iwlwifi 4965AGN wireless drivers on Ubuntu

2007-06-18T22:59:00.000-07:00

This guide is not actual anymore. Just update to the latest Ubuntu Gutsy and boot with the generic kernel. The wireless module is not automatically loaded, so you must do it manually

sudo modprobe iwl4965

The old guide:

Download some source code


wget http://intellinuxwireless.org/iwlwifi/downloads/iwlwifi-0.0.32.tgz
tar -xzf iwlwifi-0.0.32.tgz

wget http://intellinuxwireless.org/mac80211/downloads/mac80211-8.0.1.tgz
tar -xzf mac80211-8.0.1.tgz

wget http://intellinuxwireless.org/iwlwifi/downloads/iwlwifi-4965-ucode-4.44.15.tgz
tar -xzf iwlwifi-4965-ucode-4.44.15.tgz

Download the kernel source and essential compilation tools


sudo apt-get install build-essential linux-headers-`uname -r`

Link the source in to the kernels binary directory. Without this the compilation will fail.


ln -s  /usr/src/linux-headers-`uname -r` /lib/modules/`uname -r`/source

Compile the iwlwifi sources


cd mac80211-8.0.1
make patch_kernel
cd ../iwlwifi-0.0.32
make
make install

Copy the firmware in to the correct directory


cd ../iwlwifi-4965-ucode-4.44.15
cp iwlwifi-4965.ucode /lib/firmware/`uname -r`

and to load the wireless driver into the kernel:


modprobe iwl4965

If you experience problem with the system stability try to turn the hardware switch OFF before booting or rebooting your PC.

c2gnuplot

2007-05-30T12:41:00.000-07:00

I wrote a small header file for passing data from C++ to gnuplot. It works only under unix based distros. You can download from this site. Moreover, here is a nice mpeg output for a cellular automata growth model.

Install Intel ICC on Ubuntu Feisty

2007-05-19T09:37:00.000-07:00

Download the Intel ICC compiler from the Intel website
Extract the downloaded archive and run the install script

sudo tar -xzf l_cc_c_9.1.047.tar.gz sudo cd l_cc_c_9.1.047 sudo ./install.sh
The Install script will you ask for the password mailed by Intel and for your e-mail address. Finally, the install script will express its gratitude for choosing ICC. Unfortunately, the official script works only on rpm based distros, so we need some additional work.
We need to install alien

sudo apt-get install alien
convert and install the Intel rpm package to deb

sudo cd data sudo alien intel-icc_ide91047-9.1.047-1.i386.rpm sudo dpkg -i intel-icc91047_9.1.047-2_i386.deb

For different CPU architecture as i386 you need to choose another rpm file.
Now, the compiler is installed and we are nearly there ;). Edit and replace the <INSTALLDIR> string in /opt/intel/cc/9.1.047/bin/icc by "/opt/intel/cc/9.1.047/bin"

Replace the last lines:
if [ $# != 0 ] then exec -a "/opt/intel/cc/9.1.047//bin/icc" /opt/intel/cc/9.1.047//bin/iccbin "$@"; else exec -a "/opt/intel/cc/9.1.047//bin/icc" /opt/intel/cc/9.1.047//bin/iccbin; fi
by

exec -a "/opt/intel/cc/9.1.047/bin/icc" /opt/intel/cc/9.1.047/bin/iccbin "$@";

save the changed file.
Finally we need to register the icc libraries
gksudo gedit /etc/ld.so.conf.d/icc.conf
and paste a single line
/opt/intel/cc/9.1.047/lib/

Save the icc.conf file and run
sudo ldconfig
Set the global path to the icc binaries
sudo -i echo PATH=\$PATH:/opt/intel/cc/9.1.047/bin >> /etc/profile
Enjoy!

How to create a dynamic SSH tunnel and use your distant computer to access the Internet?

2007-01-01T13:45:00.000-08:00

To create a tunnel with dynamic port allocation open your terminal and write

ssh -N -f -D 1234 login@ServerIP

and set the socks proxy in your firefox browser to "localhost:1234".
In Firefox open the address about:config.
In the filter box enter "DNS" and set the network.proxy.socks_remote_dns option to "true". This will allow to resolve the DNS address trough the ssh proxy.

For the unlimited freedom in tunneling install the FoxyProxy firefox plugin for fast proxy switching.

Auto-sync and backup directories to ipod at connection to Ubuntu Edgy

2006-12-27T01:03:00.000-08:00

This is a simple script to auto backup important directories to my ipod and sync the Evolution calendar.
The scripts depends on the gtkpod package

Steps:

Install gtkpod
Copy this script to your ~/bin/ directory and change DIRS_FOR_BACKUP variable.
chmod u+x ~/bin/ipodsync.sh
In System > Preferences > Removable Drives and Media > Multimedia > Portable Music Players
write
~/bin/ipodsync.sh %m
Connect the ipod

How to create a new environment in LaTeX

2006-12-25T12:45:00.000-08:00

This is an example how to create a new environment in latex.
The \newenvironment command have two important parts: the begin code and the and code. The begin code is executed when the environment is initialized (in our case \begin{example}) and the end code executed at the \end{example} command.



\documentclass[a4paper,12pt,oneside]{article}
\newcounter{Examplecount}
\setcounter{Examplecount}{0}
\newenvironment{example}
{% This is the begin code
\stepcounter{Examplecount}  {\bf\small Example} \arabic{Examplecount}\scriptsize \begin{it}
}
{% This is the end code
\end{it} }

\begin{document}

\begin{example}
This is an example
\end{example}

\end{document}