Dec 28, 2009

Dbus error while mounting

error:
unable to mount DBus error mount -t ntfs-3g

solution:
sudo mount -t ntfs-3g /dev/sdb1 /yourplace/ -o force

Dec 25, 2009

why my ubuntu net connection is slow?? how to fix

1) Change Firefox settings

* In firefox, type on the web browser's address box: about:config
* Find this phrase network.dns.disableIPv6
* Change its value to "true"
2) IPV6 settings
* Start a shell prompt
* Type -> sudo gedit /etc/modprobe.d/aliases
* Find this phrase: alias net-pf-10 ipv6 and comment this line as: # alias net-pf-10 ipv6
* Add this phrase under your commented line: alias net-pf-10 off
3) Restart your computer

Test your internet speed

Test your internet speed:

http://www.speedtest.net/

Dec 21, 2009

I love linux

1. I can extract something with one command without opening a separate program.

tar xjvf cornbread.tar.bz2

2. I can print a document without opening it.

http://tldp.org/HOWTO/Printing-Usage-HOWTO-2.html

3. I can update all applications with two magical words, apt-get upgrade.

apt-get upgrade

4. Its free

Download here: http://www.linux.org/dist/download_info.html

5. Its free as in beer.

6. Its more secure than Windows

Look : http://wiki.answers.com/Q/Why_is_Linux_more_secure_than_Windows

7. I can run on pretty much any hardware.

8. It is highly scalable… I can install it on a 486 or a dual core.

9. Help is readily available and free of charge.

Look: http://www.linuxhelp.net/

10. Well documented

Look: http://www.linux.org/docs/

11. No need for some obscure knowledge base

Your grandma even can use =) : http://bugsanddebugs.blogspot.com/2009/11/ubuntu-for-your-grandmother.html

12. A standard help system that is actually useful (man)

Look: http://linuxmanpages.com/

13. Powerful Command Line Interface

14. Many of the best programs are available for Linux for free. ie. Apache, MySQL, ProFTPd, SSH, OpenVPN. You would have to pay hundreds if not thousands of dollars for Windows programs that accomplish the same thing. On top of that you will have to pay for support

15. No need to call a tech support center in India to activate your fully legal OS.

GNU FREE !!! http://www.gnu.org/

16. Linux can be configured to run without a GUI for max performance. This is especially useful for servers. Other operating systems don’t have this luxury.

17. It doesn’t ask me if I am sure I want to delete something….twice

rm -f -r {file-name}

18. Many of the programs are configured with a simple config file. This makes editing much easier than navigating through pages and pages of tabs and radio check boxes. You can even structure your config file with your own comments to make editing easier for you. Change something often? Put it near the top. If you switch something on and off often and it is buried behind 9 gui screens it might take you 10 5 times longer to switch it.

./configure
make
make install

19. Linux will actually give you a reason why something had an error.

20. Linux wont tell me that my automatic updates are turned off every single minute of every day.

21. When I update Linux it won’t turn on a firewall automatically without my permission (Windows XP SP3 does this) and turn on services I had previously set to disabled.

22. Linux pretty much forces you to be a “non-administrative” user.

SUDO RULLAZ!

23. You can unmount something really fast with one command. Instead of double clicking on a silly icon navigating through all the USB devices plugged in select the right one only to find out that the device you are trying to unmount cannot be unmounted at this time.

umount device

24. Depending on the distro it is a lot easier to install than Windows.

my favourite: UBUNTU

25. Linux detects and installs more drivers for my hardware than Windows.

26. Linux comes with drivers for my onboard Sata where Windows XP does not.

27. Linux comes out with a new kernel constantly. Windows comes out with one once every couple years.

kernel distros: http://www.kernel.org/

28. With Linux we can compile our own kernel so we don’t have to a wear a one size fits all hat.

Look: http://www.cyberciti.biz/tips/compiling-linux-kernel-module.html

29. You can choose which type of desktop environment you want.

KDE or GNOME ?? www.kde.org/ www.gnome.org/

30. You don’t have to worry about spyware, viruses, or worms. Even if they were prevalent they couldn’t be installed unless you did it yourself.

31. When you “end a task” in Linux it actually works.

Kill commands: http://bugsanddebugs.blogspot.com/2009/12/kill-process.html

32. You can check your CPU’s temperature without installing any software.

Look: http://www.cpanelconfig.com/how-to/how-to-monitor-cpu-temperature-in-your-linux-box/

33. The command line auto complete feature works the way you expect it to.

Try tab key button while you're on the shell prompt.

34. To list the contents of a directory I only have to use two keys instead of three (ls vs. dir).

=)

35. Linux’s CLI actually ads value to the OS.

36. I can build a computer myself and still get a good price on the retail version of Linux (free).

Kernel compilation and you'll get a lovely linux..

37. I can control my computer remotely with SSH. Windows comes with remote desktop which was not encrypted last time i checked. It also was slow and supports only a few connected users unless you pay Microsoft more money for a terminal server.

38. Linux tends not to hide details

39. I can see the OS uptime without installing some Microsoft power user program.

40. Linux comes with a program that will eject my CD-Rom. This comes in handy when making automated CD backups and other scripts.

41. Linux passwords cannot be cracked in seconds like Windows.

42. I can print an entire directory of pdfs with ‘lpr *.pdf‘. In Windows you would have to open each with Foxit Reader or the bloated Adobe Acrobat.

43. You can have really cool desktop effects that rival even OSX effects.

Try compiz: http://www.compiz.org/

44. You can choose a filesystem that better fits your needs. With Windows you have two options old out of date crappy NTFS or even more out dated FAT32.

You can see your windows files in linux but you can't even see the linux partition on
windows

45. If you loose your Linux CD or don’t feel like downloading one you can get one mailed for free (ubuntu).

46. It supports more than 3/4gb of ram without updates and hacks.

47. You can get all applications you need without opening your browser or getting out your wallet and many times they are better than commercial solutions.

Holy apt-get =)

48. It doesn’t crash… ever… Its so reliable companies have used it as dedicated router firmware.

49. You don’t have to pay more money for multiple connected users.

50. When there is a security exploit I can expect a patch the next day not the second Tuesday of every month.

With the help of: http://www.marksanborn.net/linux/50-reasons-why-i-love-linux/ for reasons..


Dec 17, 2009

A Game Programming Site

Check this out : http://www.swiftless.com/tutorials/gmaker/gmakertuts.html

Kill process

For specific command:
Step #1: First, you need to find out process PID (process id)

Use ps command or pidof command to find out process ID (PID). Syntax:
ps aux | grep processname
pidof processname

For example if process name is lighttpd, you can use any one of the following command to obtain process ID:
# ps aux | grep lighttpd

Output:

lighttpd  3486  0.0  0.1   4248  1432 ?        S    Jul31   0:00 /usr/sbin/lighttpd -f /etc/lighttpd/lighttpd.conf
lighttpd 3492 0.0 0.5 13752 3936 ? Ss Jul31 0:00 /usr/bin/p

OR use pidof command which is use to find the process ID of a running program:
# pidof lighttpd

Output:

3486

Step #2: kill process using PID (process id)

Above command tell you PID (3486) of lighttpd process. Now kill process using this PID:
# kill 3486
OR
# kill -9 3486
Where,

  • -9 is special Kill signal, which will kill the process

killall command examples

DO NOT USE killall command on UNIX system (Linux only command). You can also use killall command. The killall command kill processes by name (no need to find PID):


# killall -9 lighttpd
Kill Firefox process:


# killall -9 firefox-bin


As I said earlier killall on UNIX system does something else. It kills all process and not just specific process. Do not use killall on UNIX system (use kill -9).



Dec 13, 2009

Linux File Systems Versus Windows-Based File Systems

Although similar in many ways, the Linux file system has some striking differences from file systems used in MS-DOS and Windows operating systems. Here are a few:
* In MS-DOS and Windows file systems, drive letters represent different storage devices (for example, A: is a floppy drive and C: is a hard disk). In Linux, all storage devices are fit into the file system hierarchy. So, the fact that all of /usr may be on a separate hard disk or that /mnt/rem1 is a file system from another computer is invisible to the user.

* Slashes, rather than backslashes, are used to separate directory names in Linux. So, C:\home\chris in an MS system is /home/chris in a Linux system.

* Filenames almost always have suffixes in DOS (such as .txt for text files or .doc for word- processing files). Although at times you can use that convention in Linux, three-character suffixes have no required meaning in Linux. They can be useful for identifying a file type. Many Linux applications and desktop environments use file suffixes to determine the contents of a file. In Linux, however, DOS command extensions such as .com, .exe, and .bat don’t necessarily signify an executable (permission flags make Linux file executable).

* Every file and directory in a Linux system has permissions and ownership associated with it. Security varies among Microsoft systems. Because DOS and MS Windows began as single-user systems, file ownership was not built into those systems when they were designed. Later releases added features such as file and folder attributes to address this problem.


Reference: Negus, Linux Bible 2007

Working with the Linux File System

The Linux file system is the structure in which all the information on your computer is stored.Files are organized within a hierarchy of directories. Each directory can contain files, as well as other directories.

If you were to map out the files and directories in Linux, it would look like an upside-down tree. At the top is the root directory, which is represented by a single slash (/). Below that is a set of common directories in the Linux system, such as bin, dev, home, lib, and tmp, to name a few. Each of those directories, as well as directories added to the root, can contain subdirectories. Figure illustrates how the Linux file system is organized as a hierarchy. To demonstrate how directories are connected, the figure shows a /home directory that contains subdirectories for three users: chris, mary, and tom. Within the chris directory are subdirectories: briefs, memos, and personal. To refer to a file called inventory in the chris/memos directory, you can type the full path of /home/chris/memos/inventory. If your current directory is /home/chris/memos, you can refer to the file as simply inventory.
Some of the Linux directories that may interest you include the following:
* /bin — Contains common Linux user commands, such as ls, sort, date, and chmod.
* /boot — Has the bootable Linux kernel and boot loader configuration files (GRUB).
* /dev — Contains files representing access points to devices on your systems. These include terminal devices (tty*), floppy disks (fd*), hard disks (hd*), RAM (ram*), and CD-ROM (cd*). (Users normally access these devices directly through the device files.)
* /etc — Contains administrative configuration files.
* /home — Contains directories assigned to each user with a login account.
* /media — Provides a standard location for mounting and automounting devices, such as remote file systems and removable media (with directory names of cdrecorder, floppy, and so on).
* /mnt — A common mount point for many devices before it was supplanted by the standard /media directory. Some bootable Linux systems still used this directory to mount hard disk partitions and remote file systems.
* /proc — Contains information about system resources.
* /root — Represents the root user’s home directory.
* /sbin — Contains administrative commands and daemon processes.
* /sys (A /proc-like file system, new in the Linux 2.6 kernel and intended to contain files for getting hardware status and reflecting the system’s device tree as it is seen by the kernel. It pulls many of its functions from /proc.
* /tmp — Contains temporary files used by applications.
* /usr — Contains user documentation, games, graphical files (X11), libraries (lib), and a variety of other user and administrative commands and files.
* /var — Contains directories of data used by various applications. In particular, this is where you would place files that you share as an FTP server (/var/ftp) or a Web server (/var/www). It also contains all system log files (/var/log) and spool files in /var/spool (such as mail, cups, and news). The file systems in the DOS or Microsoft Windows operating systems differ from Linux’s file structure, as the “Linux File Systems Versus Windows-Based File Systems” explains.


Reference: Negus, Linux Bible 2007

What's So Great About Linux??

Leveraging work done on UNIX and GNU projects helped to get Linux up and running quickly. The culture of sharing in the open source community and adoption of a wide array of tools for communicating on the Internet have helped Linux to move quickly through infancy and adolescence to become a mature operating system.
The simple commitment to share code is probably the single most powerful contributor to the growth of the open source software movement in general, and Linux in particular. That commitment has also encouraged involvement from the kind of people who are willing to contribute back to that community in all kinds of ways. The willingness of Linus to incorporate code from others in the Linux kernel has also been critical to the success of Linux. The following sections characterize Linux and the communities that support it.

Features in Linux
If you have not used Linux before, you should expect a few things to be different from using other
operating systems. Here is a brief list of some Linux features that you might find cool:

* No constant rebooting — Uptime is valued as a matter of pride (remember, Linux and other UNIX systems are most often used as servers, which are expected to, and do, stay up 24/7/365). After the original installation, you can install or remove most software without having to reboot your computer.
* Start/stop services without interrupting others — You can start and stop individual services (such as Web, file, and e-mail services) without rebooting or even interrupting the work of any other users or features of the computer. In other words, you should not have to reboot your computer every time someone sneezes. (Installing a new kernel is just about the only reason you need to reboot.)
* Portable software — You can usually change to another Linux, UNIX, or BSD system and still use the exact same software! Most open source software projects were created to run on any UNIX-like system and many also run on Windows systems, if you need them to. If it won’t run where you want it to, chances are that you, or someone you hire, can port it to the computer you want. (Porting refers to modifying an application or driver so it works in a different computer architecture or operating system.)
* Downloadable applications — If the applications you want are not delivered with your version of Linux, you can often download and install them with a single command, using tools such as apt, urpmi and yum.
* No settings hidden in code or registries — Once you learn your way around Linux, you’ll find that (given the right permissions on your computer) most configuration is done in plain text files that are easy to find and change. Because Linux is based on openness, nothing is hidden from you. Even the source code, for GPL-covered software, is available for your review.
* Mature desktop — The X Window System (providing the framework for your Linux desktop) has been around longer than Microsoft Windows. The KDE and GNOME desktop environments provide graphical interfaces (windows, menus, icons, and so forth) that rival those on Microsoft systems. Ease-of-use problems with Linux systems are rapidly evaporating.
* Freedom — Linux, in its most basic form, has no corporate agenda or bottom line to meet. You are free to choose the Linux distribution that suits you, look at the code that runs the system, add and remove any software you like, and make your computer do what you want it to do. Linux runs on everything from supercomputers, to cell phones, and everything in between. Many countries are rediscovering their freedom of choice and making the switch at government and educational levels. France, Germany, Korea, and India are just a few that have taken notice of Linux. The list continues to grow.

There are some aspects of Linux that make it hard for some new users to get started. One is that Linux is typically set up to be secure by default, so you need to adjust to using an administrative login (root) to make most changes that affect the whole computer system. Although this can be a bit inconvenient, trust me, it makes your computer safer than just letting anyone do anything. This model was built around a true multi-user system. You can set up logins for everyone that uses your Linux computer, and you (and others) can customize your environment however you see fit without affecting anyone else’s settings. For the same reason, many services are off by default, so you need to turn them on and do at least minimal configuration to get them going. For someone who is used to Windows, Linux can be difficult just because it is different than Windows. But because you’re reading this book, I assume youwant to learn about those differences.



Reference: Negus, Linux Bible 2007

Understanding Linux

People who don’t know what Linux is sometimes ask me if it’s a program that runs on Microsoft Windows. When I tell them that Linux is, itself, an operating system like Windows and that they can remove (or never purchase) Windows, I sometimes get a surprised reaction: “A PC can run with nothing from Microsoft on it?” The answer is yes!

The next question about Linux is often: “How can Linux be free?” While the full answer to that is a bit longer, the short answer is: “Because the people who write the code license it to be freely distributed.” Keep in mind, however, that the critical issue relating to the word “free” is “freedom,” meaning that you are free to rebuild, reuse, reconfigure, and otherwise do what you like with the code. The only major responsibility is that if you change the software, you pass it forward so that others may benefit from your work as well.

Linux is a full-blown operating system that is a free clone of the powerful and stable UNIX operating system. Start your computer with Linux, and Linux takes care of the operation of your PC and manages the following aspects of your computer:

* Processor — Because Linux can run many processes from many different users at the same time (even with multiple CPUs on the same machine), Linux needs to be able to manage those processes. The Linux scheduler sets the priorities for running tasks and manages which processes run on which CPUs (if multiple processors are present). The scheduler can be tuned differently for different types of Linux systems. If it’s tuned prop erly, the most important processes get the quickest responses from the processor. For example, a Linux scheduler on a desktop system gives higher priority to things such as moving a window on the desktop than it does to a background file transfer.

* Memory — Linux tries to keep processes with the most immediate need in RAM, while managing how processes that exceed the available memory are moved to swap space. Swap space is a defined area on your hard disk that’s used to handle the overflow of running processes and data. When RAM is full, processes are placed in swap space. When swap space is full (something that you don’t want to happen), new processes can’t start up.

* Devices — Linux supports thousands of hardware devices, yet keeps the kernel a manageable size by including only a small set of drivers in the active kernel. Using loadable modules, the kernel can add support for other hardware as needed. Modules can be loaded and unloaded on demand, as hardware is added and removed. (The kernel, described in detail a bit later on, is the heart of a Linux operating system.)

* File systems — File systems provide the structure in which files are stored on hard disk, CD, DVD, floppy disks, or other media. Linux knows about different file system types (such as Linux ext3 and reiserfs file systems, or VFAT and NTFS from Windows systems) and how to manage them.

* Security — Like UNIX, Linux was built from the ground up to enable multiple users to access the system simultaneously. To protect each user’s resources, every file, directory, and application is assigned sets of read, write, and execute permissions that define who can access them. In a standard Linux system, the root user has access to the entire system, some special logins have access to control particular services (such as Apache for Web services), and users can be assigned permission individually or in groups. Recent features such as Security Enhanced Linux enable more refined tuning and protection in highly secure computing environments.

What I have just described are components that are primarily managed by what is referred to as the Linux kernel. In fact, the Linux kernel (which was created and is still maintained by Linus Torvalds) is what gives Linux its name. The kernel is the software that starts up when you boot your computer and interfaces with the programs you use so they can communicate effectively and simply with your computer hardware.

Components such as administrative commands and applications from other free and open source software projects work with the kernel to make Linux a complete operating system. The GNU proj ect, in particular, contributed many implementations of standard UNIX components that are now in Linux. Apache, KDE, GNOME, and other major open source projects in Linux,have also contributed to the success of Linux. Those other projects added such things as:

* Graphical user interfaces (GUIs) — Consisting of a graphical framework (typically the X Window System), window managers, panels, icons, and menus. GUIs enable you to use Linux with a keyboard and mouse combination, instead of just typing commands (as was done in the old days).

* Administrative utilities — Including hundreds (perhaps thousands) of commands and graphical windows to do such things as add users, manage disks, monitor the network, install software, and generally secure and manage your computer.

* Applications — Although no Linux distribution includes all of them, there are literally thousands of games, office productivity tools, Web browsers, chat windows, multimedia players, and other applications available for Linux.

* Programming tools — Including programming utilities for creating applications and libraries for implementing specialty interfaces.

* Server features — Enabling you to offer services from your Linux computer to another computer on the network. In other words, while Linux includes Web browsers to view Web pages, it can also be the computer that serves up Web pages to others. Popular server features include Web, mail, database, printer, file, DNS, and DHCP servers.

Once Linus Torvalds and friends had a working Linux kernel, pulling together a complete open source operating system was possible because so much of the available “free” software was:

* Covered by the GNU Public License (GPL) or similar license — That allowed the entire operating system to be freely distributed, provided guidelines were followed relating to how the source code for that software was made available going forward (see http://www.gnu.org/licenses/gpl.html).

* Based on UNIX-like systems — Clones of virtually all the other user-level components of a UNIX system had been created. Those and other utilities and applications were built to run on UNIX or other UNIX-like systems.

Linux has become one of the most popular culminations of the open source software movement.But the traditions of sharing code and building communities that made Linux possible started years before Linux was born. You could argue that it began in a comfortable think tank known as Bell Laboratories.





Reference: Negus, Linux Bible 2007

Dec 13...


(13 Dec 2001 to 2009)
I remember you, Chuck Schuldiner..... I'll always remember you..

miss you pal, it's been 8 years ! you pain is still with me...

Dec 10, 2009

printf

Where specifier is the most significant one and defines the type and the interpretation of the value of the coresponding argument:
specifierOutputExample
c Charactera
d or i Signed decimal integer392
e Scientific notation (mantise/exponent) using e character3.9265e+2
E Scientific notation (mantise/exponent) using E character3.9265E+2
f Decimal floating point392.65
g Use the shorter of %e or %f392.65
G Use the shorter of %E or %f392.65
o Signed octal610
s String of characterssample
u Unsigned decimal integer7235
x Unsigned hexadecimal integer7fa
X Unsigned hexadecimal integer (capital letters)7FA
p Pointer addressB800:0000
nNothing printed. The argument must be a pointer to a signed int, where the number of characters written so far is stored.
% A % followed by another % character will write % to stdout.

Dec 8, 2009

Mounted or unmounted?

As root, you can issue the following command to view the naming combinations possible for your system:

$ ls /dev/sda*

[Output]
/dev/sda /dev/sda1 /dev/sda2 /dev/sda5 /dev/sda6 /dev/sda7 /dev/sda8

$ df -h

[Output]
Filesystem Size Used Avail Use% Mounted on
/dev/sda5 39G 12G 26G 31% /
tmpfs 1012M 0 1012M 0% /lib/init/rw
varrun 1012M 256K 1012M 1% /var/run
varlock 1012M 0 1012M 0% /var/lock
udev 1012M 2.8M 1009M 1% /dev
tmpfs 1012M 164K 1012M 1% /dev/shm
lrm 1012M 2.2M 1010M 1% /lib/modules/2.6.27-16-generic/volatile
/dev/sda6 39G 35G 2.4G 94% /home
/dev/sda7 29G 25G 3.2G 89% /media/disk


Listing Hardrives
$ sudo fdisk -l

Dec 5, 2009

Debian / Ubuntu linux install kernel headers package

Make sure you have updated version
$ sudo apt-get update

Search for kernel version (optional)
$ apt-cache search linux-headers-$(uname -r)

Install linux-header package
$ sudo apt-get install linux-headers-$(uname -r)

Nov 20, 2009

How to play VIDEO_TS.IFO, VIDEO_TS.BUP, VOB (ripped DVD) files?

Step 1. To play a copied/ripped DVD from hard disk you can use VideoLAN (VLC Player): Click here to download this player

Step 2. Install it. Start VideoLAN (click Start -> Programs -> VideoLAN -> VLC Media Player)

Step 3. Click File -> Open Directory. Find the VIDEO_TS folder, select it and click OK.

Please note, you have to copy all the ripped data to the right place. Create a VIDEO_TS folder and copy all the ripped files there.


Other solutions:

In order to play a copied DVD with WinDVD you must right-click on the player (menu will pop up), choose Source -> DVD From Folder, find and open your VIDEO_TS folder.
To play a copied DVD with PowerDVD you click on the open button and choose Open DVD File from the Hard Disk Drive and open the video_ts.ifo.
To play VIDEO_TS using ANY PLAYER download and install MPEG2 Decoder. After that, find your VIDEO_TS folder and open VOB files (such as VTS_01_1.VOB, VTS_01_2.VOB, VTS_01_3.V0B etc.).


Let's explain what is inside VIDEO_TS:

VIDEO_TS.IFO, VTS_01_0.IFO - are configuration files with information about how to play exactly all video and audio content of DVD (including menus, subtitles, aspect ratio, languages etc.).

VIDEO_TS.BUP, VTS_01_0.BUP - backup of configuration files.

VTS_01_1.VOB, VTS_01_2.VOB, VTS_01_3.V0B, ... - files with video and audio data.



Nov 16, 2009

How to remote control windows from Ubuntu

Everyone should be able to control remote windows by Remote Desktop Connection application, but don't know how to connect to windows in linux platform.
You can fetch it from here.
That's a easy procedure for you.

1. Enable remote desktop function in windows first. You can follow below diagram to activate remote desktop and add aaa account that is a example account and password is aaa in windows platform.





2. Select Applications --> Internet --> Terminal Server Client in Ubuntu



3. It will pop-up a configuration window of Terminal Sever Client, please chose RDPv5 in the Protocol table.



4. Please click Connect button after filled all information.
Computer: Destination host IP address
User Name: aaa
Password: aaa




5. You will connect to destination computer successfully. The snapshot as below



Enabling Yahoo accounts with pidgin

Open Pidgin and go to Accounts -> Manage Accounts...

Review image


· Click on the Yahoo account and then on the "Modify" button...

Review image


· Click on the "Advanced" tab and paste the following line in the "Pager server" field...

cn.scs.msg.yahoo.com

Review image


Click the "Save" button, then click the check box in front of the Yahoo account to connect.

Nov 8, 2009

12 Awesome French Short Animations

Oktapodi (Gobelins)

oktapodi

Trying to scape of a assistant chef, two octopus find them selves into a funny runaway for theirs lives. This great animation was nominated for the Oscars Academy Award on the category of short film (animated), almost at the same level of Presto from Pixar.

Made by: Julien BOCABEILLE, François-Xavier CHANIOUX, Olivier DELABARRE, Thierry MARCHAND, Quentin MARMIER and Emud MOKHBERI

Watch Oktapodi




Hugh (esma)


A great animation school from Montpellier bring to us this great animation when an old shaman was telling a story to 3 young children. Ages ago, some human beings had big troubles because the sky was too low. Birds could not fly and men were bended, until one day…

Made by: MATHIEU NAVARRO, SYLVAIN NOUVEAU, AURORE TURBE and FRANCOIS POMMIEZ

Watch Hugh

Mon(s)tre (lisaa)

monstre

This is a strange story about our perception of time, it could be relative for each person or statics for others, but at the end we have so many issues with it, that it depends of us how we use it. This is an animation inspired by the universe of Myiazaki, was made as a final carrier project of a 2d animation school.

Made by: Geofforel Ridel , Yann Poyac and Charless Chneck

Watch mon(s)tre

Blind spot (gobelins)

blind_spot

Another great animation from Gobelins as a third year project, this is the story of an unlucky thief get in to a market trying to make his job, but in the market an old and almost blind lady finish her purchase and go home. At the end everything could be confused, or really clear for the police.

Made by: Johanna BESSIERE , Cécile DUBOIS HERRY, Simon ROUBY, Nicolas CHAUVELOT, Olivier CLERT and Yvon JARDEL.

Watch Blind Spot

Pirates (Gobelins)

pirates

Another beautiful animation from this school made as an opening short for the Annecy 2006 international animation festival. Is basically 2D traditional animation with some scenes made in 3D, the result its a great and clean animation with a funny story.

Made by: Yves BIGEREL, Bruno DEQUIER, Ben FIQUET, Nicolas GUEROUX, Julien LE ROLLAND

Watch Pirates

up (Emile Cohl)

wake_up

An animation based on a colorful confrontation between a young artist trying to express herself by tagging on the streets of a gray city and a boring house-painter who is constantly having to cover up graffiti, even this could be the reality of a city like Paris or New York.

Made by: Marie-Clémence Gautier

Watch Wake up

Sigg Jones (supinfo)

sigg_jones

What could happen when the heavy weight champion wrestler Sigg Jones drinks a strange Power drink? he loses control of himself unleashing all the good he had… This is one of my favorites animations by the dynamic of the characters movements, this was made by three students from Supinfocom School in France, using 3DSmax.

Made by: Mathieu Bessudo, Douglas lassance and Jonathan Vuillemin

Watch Sigg Jones

La main des maitres (Eesa)

la_main_des_maitres

From the George Mellies school as a third year animation project this is the history of two young working on the middle of a big war, trying to make the things worth for the people on the city even if they have to risk their lives, trying to make the message. A great storyline with a mix of techniques

Made by: Looky , Clément Delatre and Adrien “CaYuS” Toupet

Watch La main des maitres

Animadanse (Eesa)

animadanse

A dream come true for a cleaning guy when he discovers a new spice of monsters who love him, he became what he’s always dreamed. A great mix between 3d animation and reality, and a good domain of the human body animation put in to a break dancer character, which is no to easy.

Made by: Julien Badoil , Bertrand de Becque and Larson Liberin de Shoriba Diop

Watch Animadanse

Jungle jail (esma)

jungle_jail

Montpelier bring to us another cool animation about a young little man who arrived in a prison where the strongest prisoner is the boss, and the other are his slaves, until the moment of the confrontation between the two principal characters, anything can happen in this prison, even you could became the most powerful guy on the place.

Made By: Mathieu Arnoux, Jugo Cierzniak , Bruce Nguyen Van Lan and Aimeric palermo

Watch Jungle Jail

Gary (supinfo)

gary

From Supinfo school we have this beautiful animation made in 3d but with a look 2d , the story of a little boy who is in love of his beautiful and older girl-friend, he dreams with waiting for the day when he’ll be older and she loves him back.

Made by: Yann Benedi , Quetin Chaillet and Clement Soulmagnon

Watch Gary

A Quoi Ca Sert L’Amour (bonus1)

a_quoi_ca_sert_lamour

An old student of Les Gobelins made this great 2d animation based on Edith Piaf song. It could be your love history as a normal couple like the others, with all the good and bad things this would bring to you. The most important… right now he works in pixar.

Made by: Louis Clichy

Watch A quoi ça sert l’amour

Galactic Mail (bonus2)

galactic_mail

A beautiful animation made by Douglas Lassance and Jonathan Vuillemin (the guys behind Sigg Jones), you’ll recognize their animation style and rhythm. This is a story about and intergalactic space race between FedEx and UPS.

Produced by The Mill

Watch Glactic Mail

Reference: http://www.blog.exxcorpio.com/2009/06/29/12-awesome-french-short-animations/


Nov 6, 2009

Ubuntu for your grandmother

This article was recently featured in Full Circle magazine. Please visit their site or download the edition here .

x

They say its for geeks, they say its for nerds, they say its for those whose pinkie finger has the imprint of the enter key tattooed on it. We say its for your grandmother ! Yes my friends, I kid you not, for all of those who are afraid to dip their little toe into the great Linux-Lake let us reassure you : If your grandmother can do it ? So can you. Before we start , let me clarify : We are not talking about turning your Linux machine into a clustered database server with SQL, PHP, Apache, Samba and what have you. We are talking about the advantages of using Linux .. as a desktop.




Why this experiment.

I have been toying around with Linux since 1999, Seen the first desktop versions evolve and have seen the Linux OS grow in strength on the desktop. Last year I found out about Ubuntu Linux and have been doing several articles and podcasts on the use of Ubuntu as a desktop system. I am by no means a Linux zealot ! No pingu-pimping for me ! Drop me in the Linux command line and I'm as lost as Debby Harry in a hair salon. I do however have a philosophy about computer use. I think technology should be safe and simple and that a computer should work for you and not the other way around. Linux has always been seen as to hard and to complicated. So it was time for a little experiment. Could we put together a Linux desktop system that was simple to use, safe from virusses spam and user mistakes, and had a lot of software to offer. Could we build a Linux box that your grandma could use ? Well , lets see.

Step one : Find a grandmother.

My fiancé's family is pretty tech savvy , her dad is a computer wizz, her mother is on MSN messenger all day, her sisters live on line and her grandmother .. is right up the alley. Its not that they are all computer freaks out there , they all just have an open mind towards technology. Good old granny started out on her gaming trip some fifteen years ago when she swiped a hand-console Tetris game from one of her grandchildren. An all night-gaming rush that night got her hooked on these little hand held gaming consoles. Some two years ago she got a second hand worn down IBM Thinkpad laptop running windows 95 for running some simple games like .. surprise surprise.. Tetris and stuff. So when she called me last week in a panic that she accidentally deleted some shortcuts and 'could not get her games to work anymore'and in her despair, was even suggesting buying herself a brand new laptop .. it was time to jump in .

Meme

meme

Step Two : Find a laptop

Finding a laptop for cyber-granny was not all that hard. My fiancé's dad had an old Compaq laptop lying around that was no longer in active duty. With an 800 mhz Processor and 256 meg of ram it had been set out to pasture because of a defective PCMCIA slot on the motherboard. Apparently force feeding a PCMCIA card upside down into its slot does not bode well for the laptop. So it did no longer have wireless capability and since the family had bought a new laptop .. it was just laying around. One discarded laptop, one grandma in need .. Cheque please !

Step Three : Somebody get me a penguin.

With our laptop secured under our arm it was time to browse trough some available operating systems to help “La mama” out. The quota's that needed to be met were :

  • A : Be simple in use.

  • B: be safe from mallware virusses and user-boo-boo's.

  • C: offer enough software without having to take on a loan to get you started.

This kind of ruled out Windows XP pro right off the bat. Several Linux distributions offered themselves up but thanks to the fantastic automatix script, Ubuntu took the cake.

So it was time to let loose the beast. Downloading a standard iso Image from the 5.10 version was about 20 minutes work and the whole installation process took about an hour. The simple installation only bothered us with the country settings, keyboard layout and a user name. No problem there. We let it have the entire hard disk at its disposal so we did not have some boot loader clogging up the startup process. As easy as firing up a toaster was the objective here.

When the bongo's rumbled to announce the first successful boot up we went straight to the Synaptic package manager and started adding games to our installation. Ubuntu comes with some games in the standard configuration, but when you look in Synaptic its like uncovering the lost island of Arcadia. Some games are action based , a lot of them are brain breakers and stuff. Ideal for our test subject. We loaded the distro up with some 100 some games and that was that.

Now what do you do when you've beat Tetris for the 500th time and can't see another polygon for the rest of the evening ? You watch a movie right ? Unfortunately most Linux distributions come without support for playing mpeg2 (dvd's) and mp3 support. It has to do with some legal stuff if i remember correctly. But with Ubuntu we have a little solution for this called : The automatix script. These three lines of code will give you a little GUI in the system menu where you can select all the goodies you want. Realplayer, WMV support , Skype, DVD playback etc...

Its a simple as pie : Enter these three lines of code in your terminal window.

sudo apt-get install xterm
wget http://beerorkid.com/automatix/automatix_5.1-1_i386.deb
sudo dpkg -i automatix_5.1-1_i386.deb

When you go into the systems menu and look for the automatix application. We selected MP3, WMV, DVD playback and Flash support. Once OK is clicked, Ubuntu does it all for you. For those who are interested HERE is the automatix manual

automatix


Step Four : Sense some simplicity.

Now its no good to have a complicated system for our super granny now is it. Time to simplify the whole deal.

  • Step one : Automatic Login. In the settings menu you can choose the AUTOLOGIN feature. This makes sure our little laptop boots up straight into the users desktop. No login/password combinations but hey .. its not like she's typing up memo's for the pentagon.

Meme on Ubuntu.
  • Step two : Could i see the menu please ? thanks to the Gnome desktop the menu is pretty simple as it is (somehow the KDE setup is just too “U-bundant” for me. But a lot of options on the menu where just not needed. So we added the games menu, the dvd and cd player icon and the shutdown icon to the main menu bar and removed everything else. Next up the menu bar was set at the bottom of the screen and the bar you see below was set up top. I left an icon for the main “start” menu there so I could access all the other programs and settings if needed.

The Ubuntu Menu
  • Step three : Explaining how it works : Ok Grann, here is how it works. Press the blue button to start up the computer. Wait until you hear the music. Then you have four buttons on the bottom on the screen. One will give you a menu with ALL the games. If you want to play a movie, just pop in a dvd and click on the second button with the little film reel on it. Want to play some music ? pop in the music cd and click on the little cd. And to shut down the system just click on the little door there.

Thats it , half an hour later granny was trained into using the computer, had a shit load of games to choose from, could play movies and music cd's and was able to boot up and shutdown her system without ever having to worry about pressing the wrong button. Who EVER said Linux was hard ?

Conclusion.

Needless to say , Nana was thrilled. She had a stable and secure operating system and did not have to worry about pressing the wrong buttons because quite frankly .. there where none. A grin as wide as the Brooklyn bridge spread across her face when she saw the entire selection of games she could play and not have to worry about breaking anything in the process. “ This is much easier than the previous one” she uttered casting a wayward glance to her old Windows computer.

I”ll be keeping tabs on our cyber-grandmother in the next few weeks to see how she gets along with her new system.

Now with computers coming more and more abundant in our everyday lives, its natural that everybody wants one, including everyone in your family. But as the family-computer-geek (and professional IT consultant) it would just turn into a nightmare providing support for everyone. So using a simplified Ubuntu installation does keep calls about viruses, broken os'es and spy-ware away. Even if she decided to go on line, I would just have to add the Firefox and Gaim buttons to her menu bar, give her a crash course in chat'n-surf and she would be on her way. No high maintenance on this operating system. So to round it up ? Who ever said Linux was hard and complicated. When handled right it can be a simpler and safer operating system to plant down in the soil of an unexperienced user. Ok , you can't install all the cd's you see in the shop, but Linux comes with all these goodies built in ! This way you even save money. So the question is : Have you seen your granny lately ?

Granny in action

If you think this article rocks you might want to check out our other Ubuntu Manuals

Feisty Fawn for the Family part one : Setting up a Feisty server and controlling it with WEBMIN.

Feisty Fawn for the Family part two : Frighteningly simple filesharing for the family

Feisty Fawn for the Family part three : Torrentfun with a Torrentflux server

and more Tech Articles

Ref: http://www.knightwise.com/content/view/154/9/




Linux tips every geek should know

#1: Check processes not run by you

  • Difficulty: Expert
  • Application: bash

Imagine the scene - you get yourself ready for a quick round of Crack Attack against a colleague at the office, only to find the game drags to a halt just as you're about to beat your uppity subordinate - what could be happening to make your machine so slow? It must be some of those other users, stealing your precious CPU time with their scientific experiments, webservers or other weird, geeky things!

OK, let's list all the processes on the box not being run by you!

ps aux | grep -v `whoami`

Or, to be a little more clever, why not just list the top ten time-wasters:

ps aux  --sort=-%cpu | grep -m 11 -v `whoami`

It is probably best to run this as root, as this will filter out most of the vital background processes. Now that you have the information, you could just kill their processes, but much more dastardly is to run xeyes on their desktop. Repeatedly!

#2: Replacing same text in multiple files

  • Difficulty: Intermediate
  • Application: find/Perl



If you have text you want to replace in multiple locations, there are several ways to do this. To replace the text Windows with Linux in all files in current directory called test[something] you can run this:

perl -i -pe 's/Windows/Linux/;' test*

To replace the text Windows with Linux in all text files in current directory and down you can run this:

find . -name '*.txt' -print | xargs perl -pi -e's/Windows/Linux/ig' *.txt

Or if you prefer this will also work, but only on regular files:

find -type f -name '*.txt' -print0 | xargs --null perl -pi -e 's/Windows/Linux/'

Saves a lot of time and has a high guru rating!


#3: Fix a wonky terminal

  • Difficulty: Easy
  • Application: bash

We've all done it - accidentally used less or cat to list a file, and ended up viewing binary instead. This usually involves all sorts of control codes that can easily screw up your terminal display. There will be beeping. There will be funny characters. There will be odd colour combinations. At the end of it, your font will be replaced with hieroglyphics and you don't know what to do. Well, bash is obviously still working, but you just can't read what's actually going on! Send the terminal an initialisation command:

reset

and all will be well again.


#4: Creating Mozilla keywords

  • Difficulty: Easy
  • Application: Firefox/Mozilla

A useful feature in Konqueror is the ability to type gg onion to do a Google search based on the word onion. The same kind of functionality can be achieved in Mozilla by first clicking on Bookmarks>Manage Bookmarks and then Add a New Bookmark. Add the URL as:

http://www.google.com/search?q=%s

Now select the entry in the bookmark editor and click the Properties button. Now enter the keyword as gg (or this can be anything you choose) and the process is complete. The %s in the URL will be replaced with the text after the keyword. You can apply this hack to other kinds of sites that rely on you passing information on the URL.

Alternatively, right-click on a search field and select the menu option "Add a Keyword for this Search...". The subsequent dialog will allow you to specify the keyword to use.

#5: Running multiple X sessions

  • Difficulty: Easy
  • Application: X

If you share your Linux box with someone and you are sick of continually logging in and out, you may be relieved to know that this is not really needed. Assuming that your computer starts in graphical mode (runlevel 5), by simultaneously pressing the keys Control+Alt+F1 - you will get a login prompt. Insert your login and password and then execute:

startx -- :1

to get into your graphical environment. To go back to the previous user session, press Ctrl+Alt+F7, while to get yours back press Ctrl+Alt+F8.

You can repeat this trick: the keys F1 to F6 identify six console sessions, while F7 to F12 identify six X sessions. Caveat: although this is true in most cases, different distributions can implement this feature in a different way.


#6: Faster browsing

  • Difficulty: Easy
  • Application: KDE

In KDE, a little-known but useful option exists to speed up your web browsing experience. Start the KDE Control Center and choose System > KDE performance from the sidebar. You can now select to preload Konqueror instances. Effectively, this means that Konqueror is run on startup, but kept hidden until you try to use it. When you do, it pops up almost instantaneously. Bonus! And if you're looking for more KDE tips, make sure you check out our article, 20 all-new KDE 4.2 tips.


#7: Backup your website easily

  • Difficulty: Easy
  • Application: Backups

If you want to back up a directory on a computer and only copy changed files to the backup computer instead of everything with each backup, you can use the rsync tool to do this. You will need an account on the remote computer that you are backing up from. Here is the command:

rsync -vare ssh jono@192.168.0.2:/home/jono/importantfiles/* /home/jono/backup/

Here we are backing up all of the files in /home/jono/importantfiles/ on 192.168.0.2 to /home/jono/backup on the current machine.


#8: Keeping your clock in time

  • Difficulty: Easy
  • Application: NTP

If you find that the clock on your computer seems to wander off the time, you can make use of a special NTP tool to ensure that you are always synchronised with the kind of accuracy that only people that wear white coats get excited about. You will need to install the ntpdate tool that is often included in the NTP package, and then you can synchronise with an NTP server:

ntpdate ntp.blueyonder.co.uk

A list of suitable NTP servers is available at www.eecis.udel.edu/~mills/ntp/clock1b.html. If you modify your boot process and scripts to include this command you can ensure that you are perfectly in time whenever you boot your computer. You could also run a cron job to update the time.


#9: Finding the biggest files

  • Difficulty: Easy
  • Application: Shell

A common problem with computers is when you have a number of large files (such as audio/video clips) that you may want to get rid of. You can find the biggest files in the current directory with:

ls -lSrh

The "r" causes the large files to be listed at the end and the "h" gives human readable output (MB and such). You could also search for the biggest MP3/MPEGs:

ls -lSrh *.mp*

You can also look for the largest directories with:

du -kx | egrep -v "\./.+/" | sort -n

#10: Nautilus shortcuts

  • Difficulty: Easy
  • Application: Nautilus

Although most file managers these days are designed to be used with the mouse, it's also useful to be able to use the keyboard sometimes. Nautilus has a few keyboard shortcuts that can have you flying through files:

  • Open a location - Ctrl+L
  • Open Parent folder - Ctrl+Up
  • Arrow keys navigate around current folder.

You can also customise the file icons with 'emblems'. These are little graphical overlays that can be applied to individual files or groups. Open the Edit > Backgrounds and Emblems menu item, and drag-and-drop the images you want.


#11: Defrag your databases

  • Difficulty: Easy
  • Application: MySQL

Whenever you change the structure of a MySQL database, or remove a lot of data from it, the files can become fragmented resulting in a loss of performance, particularly when running queries. Just remember any time you change the database to run the optimiser:

mysqlcheck -o 

You may also find it worth your while to defragment your database tables regularly if you are using VARCHAR fields: these variable-length columns are particularly prone to fragmentation.


#12: Quicker emails

  • Difficulty: Easy
  • Application: KMail

Can't afford to waste three seconds locating your email client? Can't be bothered finding the mouse under all those gently rotting mountains of clutter on your desk? Whatever you are doing in KDE, you are only a few keypresses away from sending a mail. Press Alt+F2 to bring up the 'Run command' dialog. Type:

mailto:plop@ploppypants.com

Press return and KMail will automatically fire up, ready for your words of wisdom. You don't even need to fill in the entire email address. This also works for Internet addresses: try typing www.slashdot.org to launch Konqueror.


#13: Parallelise your build

  • Difficulty: Easy
  • Application: GCC

If you're running a multiprocessor system (SMP) with a moderate amount of RAM, you can usually see significant benefits by performing a parallel make when building code. Compared to doing serial builds when running make (as is the default), a parallel build is a vast improvement. To tell make to allow more than one child at a time while building, use the -j switch:

make -j4; make -j4 modules


#14: Save battery power

  • Difficulty: Intermediate
  • Application: hdparm

You are probably familiar with using hdparm for tuning a hard drive, but it can also save battery life on your laptop, or make life quieter for you by spinning down drives.

hdparm -y /dev/hdb
hdparm -Y /dev/hdb
hdparm -S 36 /dev/hdb

In order, these commands will: cause the drive to switch to Standby mode, switch to Sleep mode, and finally set the Automatic spindown timeout. This last includes a numeric variable, whose units are blocks of 5 seconds (for example, a value of 12 would equal one minute).

Incidentally, this habit of specifying spindown time in blocks of 5 seconds should really be a contender for a special user-friendliness award - there's probably some historical reason for it, but we're stumped. Write in and tell us if you happen to know where it came from!


#15: Wireless speed management

  • Difficulty: Intermediate
  • Application: iwconfig

The speed at which a piece of radio transmission/receiver equipment can communicate with another depends on how much signal is available. In order to maintain communications as the available signal fades, the radios need to transmit data at a slower rate. Normally, the radios attempt to work out the available signal on their own and automatically select the fastest possible speed.

In fringe areas with a barely adequate signal, packets may be needlessly lost while the radios continually renegotiate the link speed. If you can't add more antenna gain, or reposition your equipment to achieve a better enough signal, consider forcing your card to sync at a lower rate. This will mean fewer retries, and can be substantially faster than using a continually flip-flopping link. Each driver has its own method for setting the link speed. In Linux, set the link speed with iwconfig:

iwconfig eth0 rate 2M

This forces the radio to always sync at 2Mbps, even if other speeds are available. You can also set a particular speed as a ceiling, and allow the card to automatically scale to any slower speed, but go no faster. For example, you might use this on the example link above:

iwconfig eth0 rate 5.5M auto

Using the auto directive this way tells the driver to allow speeds up to 5.5Mbps, and to run slower if necessary, but will never try to sync at anything faster. To restore the card to full auto scaling, just specify auto by itself:

iwconfig eth0 rate auto

Cards can generally reach much further at 1Mbps than they can at 11Mbps. There is a difference of 12dB between the 1Mbps and 11Mbps ratings of the Orinoco card - that's four times the potential distance just by dropping the data rate!


#16: Unclog open ports

  • Difficulty: Intermediate
  • Application: netstat

Generating a list of network ports that are in the Listen state on a Linux server is simple with netstat:

root@catlin:~# netstat -lnp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:5280 0.0.0.0:* LISTEN 698/perl
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 217/httpd
tcp 0 0 10.42.3.2:53 0.0.0.0:* LISTEN 220/named
tcp 0 0 10.42.4.6:53 0.0.0.0:* LISTEN 220/named
tcp 0 0 127.0.0.1:53 0.0.0.0:* LISTEN 220/named
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 200/sshd
udp 0 0 0.0.0.0:32768 0.0.0.0:* 220/named
udp 0 0 10.42.3.2:53 0.0.0.0:* 220/named
udp 0 0 10.42.4.6:53 0.0.0.0:* 220/named
udp 0 0 127.0.0.1:53 0.0.0.0:* 220/named
udp 0 0 0.0.0.0:67 0.0.0.0:* 222/dhcpd
raw 0 0 0.0.0.0:1 0.0.0.0:* 7 222/dhcpd

That shows you that PID 698 is a Perl process that is bound to port 5280. If you're not root, the system won't disclose which programs are running on which ports.


#17: Faster Hard drives

  • Difficulty: Expert
  • Application: hdparm

You may know that the hdparm tool can be used to speed test your disk and change a few settings. It can also be used to optimise drive performance, and turn on some features that may not be enabled by default. Before we start though, be warned that changing drive options can cause data corruption, so back up all your important data first. Testing speed is done with:

hdparm -Tt /dev/hda

You'll see something like:

/dev/hda:
Timing buffer-cache reads:   128 MB in  1.64 seconds =78.05 MB/sec
Timing buffered disk reads: 64 MB in 18.56 seconds = 3.45MB/sec

Now we can try speeding it up. To find out which options your drive is currently set to use, just pass hdparm the device name:

hdparm /dev/hda
/dev/hda:
multcount = 16 (on)
I/O support = 0 (default 16-bit)
unmaskirq = 0 (off)
using_dma = 0 (off)
keepsettings = 0 (off)
readonly = 0 (off)
readahead = 8 (on)
geometry = 40395/16/63, sectors = 40718160, start = 0

This is a fairly default setting. Most distros will opt for safe options that will work with most hardware. To get more speed, you may want to enable dma mode, and certainly adjust I/O support. Most modern computers support mode 3, which is a 32-bit transfer mode that can nearly double throughput. You might want to try

hdparm -c3 -d1/dev/hda

Then rerun the speed check to see the difference. Check out the modes your hardware will support, and the hdparm man pages for how to set them.


#18: Uptime on your hands

  • Difficulty: Expert
  • Application: Perl

In computing, wasted resources are resources that could be better spent helping you. Why not run a process that updates the titlebar of your terminal with the current load average in real-time, regardless of what else you're running?

Save this as a script called tl, and save it to your ~/bin directory:

#!/usr/bin/perl -w

use strict;
$|++;

my $host=`/bin/hostname`;
chomp $host;

while(1) {

open(LOAD,"/proc/loadavg") || die "Couldn't open /proc/loadavg: $!\n";

my @load=split(/ /,);
close(LOAD);


print "$host: $load[0] $load[1] $load[2] at ", scalar(localtime);
print "\007";

sleep 2;
}

When you'd like to have your titlebar replaced with the name, load average, and current time of the machine you're logged into, just run tl&. It will happily go on running in the background, even if you're running an interactive program like Vim.


#19: Grabbing a screenshot without X

  • Difficulty: Easy
  • Application: Shell

There are plenty of screen-capture tools, but a lot of them are based on X. This leads to a problem when running an X application would interfere with the application you wanted to grab - perhaps a game or even a Linux installer. If you use the venerable ImageMagick import command though, you can grab from an X session via the console. Simply go to a virtual terminal (Ctrl+Alt+F1 for example) and enter the following:

chvt 7; sleep 2; import -display :0.0 -window root sshot1.png; chvt 1;

The chvt command changes the virtual terminal, and the sleep command gives it a while to redraw the screen. The import command then captures the whole display and saves it to a file before the final chvt command sticks you back in the virtual terminal again. Make sure you type the whole command on one line.

This can even work on Linux installers, many of which leave a console running in the background - just load up a floppy/CD with import and the few libraries it requires for a first-rate run-anywhere screen grabber.


#20: Access your programs remotely

  • Difficulty: Easy
  • Application: X

If you would like to lie in bed with your Linux laptop and access your applications from your Windows machine, you can do this with SSH. You first need to enable the following setting in /etc/ssh/sshd_config:

X11Forwarding yes

We can now run The GIMP on 192.168.0.2 with:

ssh -X 192.168.0.2 gimp


#21: Making man pages useful

  • Difficulty: Easy
  • Application: man

If you are looking for some help on a particular subject or command, man pages are a good place to start. You normally access a man page with man , but you can also search the man page descriptions for a particular keyword. As an example, search for man pages that discuss logins:

man -k login

When you access a man page, you can also use the forward slash key to search for a particular word within the man page itself. Simply press / on your keyboard and then type in the search term.


#22: Talk to your doctor!

  • Difficulty: Easy
  • Application: Emacs

To say that Emacs is just a text editor is like saying that a Triumph is just a motorcycle, or the World Cup is just some four-yearly football event. True, but simplified juuuust a little bit. An example? Open the editor, press the Esc key followed by X and then enter in doctor: you will be engaged in a surreal conversation by an imaginary and underskilled psychotherapist. And if you want to waste your time in a better way

Esc-X tetris

will transform your 'editor' into the old favourite arcade game.

Does the madness stop there? No! Check out your distro's package list to see what else they've bundled for Emacs: we've got chess, Perl integration, IRC chat, French translation, HTML conversion, a Java development environment, smart compilation, and even something called a "semantic bovinator". We really haven't the first clue what that last one does, but we dare you to try it out anyway! (Please read the disclaimer first!)


#23: Generating package relationship diagrams

  • Difficulty: Easy
  • Application: Debian

The most critical part of the Debian system is the ability to install a package and have the dependencies satisfied automatically. If you would like a graphical representation of the relationships between these packages (this can be useful for seeing how the system fits together), you can use the Graphviz package from Debian non-free (apt-get install graphviz) and the following command:

apt-cache dotty > debian.dot

The command generated the graph file which can then be loaded into dotty:

dotty debian.dot


#24: Unmount busy drives

  • Difficulty: Easy
  • Application: bash

You are probably all too familiar with the situation - you are trying to unmount a drive, but keep getting told by your system that it's busy. But what application is tying it up? A quick one-liner will tell you:

lsof +D /mnt/windows

This will return the command and process ID of any tasks currently accessing the /mnt/windows directory. You can then locate them, or use the kill command to finish them off.


#25: Text file conversion

  • Difficulty: Easy
  • Application: recode

recode is a small utility that will save you loads of effort when using text files created on different platforms. The primary source of discontent is line breaks. In some systems, these are denoted with a line-feed character. In others, a carriage return is used. In still more systems, both are used. The end result is that if you are swapping text from one platform to another, you end up with too many or too few line breaks, and lots of strange characters besides.

However, the command parameters of recode are a little arcane, so why not combine this hack with HACK 26 in this feature, and set up some useful aliases:

alias dos2unix='recode dos/CR-LF..l1'
alias unix2win='recode l1..windows-1250'
alias unix2dos='recode l1..dos/CR-LF'

There are plenty more options for recode - it can actually convert between a whole range of character sets. Check out the man pages for more information.


#26: Listing today's files only

  • Difficulty: Easy
  • Application: Various

You are probably familiar with the problem. Sometime earlier in the day, you created a text file, which now is urgently required. However, you can't remember what ridiculous name you gave it, and being a typical geek, your home folder is full of 836 different files. How can you find it? Well, there are various ways, but this little tip shows you the power of pipes and joining together two powerful shell commands:

ls -al --time-style=+%D | grep `date +%D`

The parameters to the ls command here cause the datestamp to be output in a particular format. The cunning bit is that the output is then passed to grep. The grep parameter is itself a command (executed because of the backticks), which substitutes the current date into the string to be matched. You could easily modify it to search specifically for other dates, times, filesizes or whatever. Combine it with HACK 26 to save typing!


#27: Avoid common mistypes and long commands

  • Difficulty: Easy
  • Application: Shell

The alias command is useful for setting up shortcuts for long commands, or even more clever things. From HACK 25, we could make a new command, lsnew, by doing this:

alias lsnew=" ls -al --time-style=+%D | grep `date +%D` "

But there are other uses of alias. For example, common mistyping mistakes. How many times have you accidentally left out the space when changing to the parent directory? Worry no more!

alias cd..="cd .."

Alternatively, how about rewriting some existing commands?

alias ls="ls -al"

saves a few keypresses if, like us, you always want the complete list.

To have these shortcuts enabled for every session, just add the alias commands to your user .bashrc file in your home directory.


#28: Alter Mozilla's secret settings

  • Difficulty: Easy
  • Application: Mozilla

If you find that you would like to change how Mozilla works but the preferences offer nothing by way of clickable options that can help you, there is a special mode that you can enable in Mozilla so that you can change anything. To access it, type this into the address bar:

about:config

You can then change each setting that you are interested in by changing the Value field in the table.

Other interesting modes include general information (about:), details about plugins (about:plugins), credits information (about:credits) and some general wisdom (about:mozilla).


#29: A backdrop of stars

  • Difficulty: Easy
  • Application: KStars

You may already have played with KStars, but how about creating a KStars backdrop image that's updated every time you start up?

KStars can be run with the --dump switch, which dumps out an image from your startup settings, but doesn't load the GUI at all. You can create a script to run this and generate a desktop image, which will change every day (or you can just use this method to generate images).

Run KStars like this:

kstars --dump --width 1024 --height 768 --filename = ~/kstarsback.png

You can add this to a script in your ~/.kde/Autostart folder to be run at startup. Find the file in Konqueror, drag it to the desktop and select 'Set as wallpaper' to use it as a randomly generated backdrop.


#30: Open an SVG directly

  • Difficulty: Easy
  • Application: Inkscape

You can run Inkscape from a shell and immediately edit a graphic directly from a URL. Just type:

inkscape http://www.somehost.com/graphic.svg

Remember to save it as something else though!


#31: Editing without an editor

  • Difficulty: Intermediate
  • Application: Various

Very long files are often hard to manipulate with a text editor. If you need to do it regularly, chances are you'll find it much faster to use some handy command-line tools instead, like in the following examples.

To print columns eg 1 and 3 from a file file1 into file2, we can use awk:

awk '{print $1, $3}' file1 > file2

To output only characters from column 8 to column 15 of file1, we can use cut:

cut -c 8-15 file1 > file2

To replace the word word1 with the word word2 in the file file1, we can use the sed command:

sed "s/word1/word2/g" file1 > file2

This is often a quicker way to get results than even opening a text editor.


#32: Backup selected files only

  • Difficulty: Intermediate
  • Application: tar

Want to use tar to backup only certain files in a directory? Then you'll want to use the -T flag as follows. First, create a file with the file you want to backup:

cat >> /etc/backup.conf
# /etc/passwd
# /etc/shadow
# /etc/yp.conf
# /etc/sysctl.conf
EOF

Then run tar with the -T flag pointing to the file just created:

tar -cjf bck-etc-`date +%Y-%m-%d`.tar.bz2 -T /etc/backup.conf

Now you have your backup.


#33: Merging columns in files

  • Difficulty: Intermediate
  • Application: bash

While splitting columns in files is easy enough, merging them can be complicated. Below is a simple shell script that does the job:

#!/bin/sh
length=`wc -l $1 | awk '{print $1}'`
count=1
[ -f $3 ] && echo "Optionally removing $3" && rm -i $3
while [ "$count" -le "$length" ] ; do
a=`head -$count $1 | tail -1`
b=`head -$count $2 | tail -1`
echo "$a $b" >> $3
count=`expr $count + 1`
done

Give to this script the name merge.sh and make it executable with:

chmod u+x merge.sh

Now, if you want to merge the columns of file1 and file2 into file3, it's just matter of executing

/path/to/merge.sh file1 file2 file3

where /path/to has to be replaced with the location of merge.sh in your filesystem.


#34: Case sensitivity

  • Difficulty: Intermediate
  • Application: bash

Despite the case of a word not making any difference to other operating systems, in Linux "Command" and "command" are different things. This can cause trouble when moving files from Windows to Linux. tr is a little shell utility that can be used to change the case of a bunch of files.

#!/bin/sh
for i in `ls -1`; do
file1=`echo $i | tr [A-Z] [a-z] `
mv $i $file1 2>/dev/null
done

By executing it, FILE1 and fiLe2 will be renamed respectively file1 and file2.


#35: Macros in Emacs

  • Difficulty: Intermediate
  • Application: Emacs

When editing files, you will often find that the tasks are tedious and repetitive, so to spare your time you should record a macro. In Emacs, you will have to go through the following steps:

  1. Press Ctrl+X to start recording.
  2. Insert all the keystrokes and commands that you want
  3. Press Ctrl+X to stop when you're done.

Now, you can execute that with

Ctrl -u  Ctrl -x e

where is the number of times you want to execute the macro. If you enter a value of 0, the macro will be executed until the end of the file is reached. Ctrl -x e is equivalent to Ctrl -u 1 Ctrl-x e.

#36: Simple spam killing

  • Difficulty: Intermediate
  • Application: KMail

Spam, or unsolicited bulk email, is such a widespread problem that almost everyone has some sort of spam protection now, out of necessity. Most ISPs include spam filtering, but it isn't set to be too aggressive, and most often simply labels the spam, but lets it through (ISPs don't want to be blamed for losing your mails).

The result is that, while you may have anti-spam stuff set up on the client-side, you can make its job easier by writing a few filters to remove the spam that's already labelled as such. The label is included as a header. In KMail, you can just create a quick filter to bin your mail, or direct it to a junk folder. The exact header used will depend on the software your ISP is using, but it's usually something like X-Spam-Flag = YES for systems like SpamAssassin.

Simply create a filter in KMail, choose Match Any of the Following and type in the header details and the action you require. Apply the filter to incoming mail, and you need never be troubled by about half the volume of your spam ever again.


#37: Read OOo docs without OOo

  • Difficulty: Intermediate
  • Application: OpenOffice.org

Have you ever been left with an OOo document, but no OpenOffice.org in which to read it? Thought you saved it out as plain text (.txt), but used the StarOffice .sxw format instead? The text can be rescued. Firstly, the sxw file is a zip archive, so unzip it:

unzip myfile.sxw

The file you want is called 'content.xml'. Unfortunately, it's so full of xml tags it's fairly illegible, so filter them out with some Perl magic:

cat content.xml | perl -p -e  "s/<[^>]*>/ /g;s/\n/ /g;s/ +/ /;"

It may have lost lots of formatting, but at least it is now readable.

#38: Find and execute

  • Difficulty: Intermediate
  • Application: find

The find command is not only useful for finding files, but is also useful for processing the ones it finds too. Here is a quick example.

Suppose we have a lot of tarballs, and we want to find them all:

find . -name '*.gz'

will locate all the gzip archives in the current path. But suppose we want to check they are valid archives? The gunzip -vt option will do this for us, but we can cunningly combine both operations, using xargs:

find . -name '*.gz' | xargs gunzip -vt


#39: Use the correct whois server

  • Difficulty: Intermediate
  • Application: whois

The whois command is very useful for tracking down Internet miscreants and the ISPs that are supplying them with service. Unfortunately, there are many whois servers, and if you are querying against a domain name, you often have to use one which is specific to the TLD they are using. However, there are some whois proxies that will automatically forward your query on to the correct server. One of these is available at http://whois.geektools.com.

whois -h whois.geektools.com  plop.info


#40: Where did that drive mount?

  • Difficulty: Intermediate
  • Application: bash

A common problem with people who have lots of mountable devices (USB drives, flash memory cards, USB key drives) is working out where that drive you just plugged in has ended up?

Practically all devices that invoke a driver - such as usb-storage - will dump some useful information in the logs. Try

dmesg | grep SCSI

This will filter out recognised drive specs from the dmesg output. You'll probably turn up some text like:

SCSI device sda: 125952 512-byte hdwr sectors (64 MB)

So your device is at sda.


#41: Autorun USB devices

  • Difficulty: Expert
  • Application: hotplug scripts

Want to run a specific application whenever a particular device is added? The USB hotplug daemon can help you! This service is notified when USB devices are added to the system. For devices that require kernel drivers, the hotplug daemon will call a script by the same name in /etc/hotplug/usb/, for example, a script called usb-storage exists there. You can simply add your own commands to the end of this script (or better still, tag a line at the end of it to execute a script elsewhere). Then you can play a sound, autosync files, search for pictures or whatever.

For devices that don't rely on kernel drivers, a lookup table is used matching the USB product and manufacturer ID. Many distros already set this up to do something, but you can customise these scripts pretty easily. See http://jphoto.sourceforge.net/?selected=sync for an example of what can be done.


#42: Rename and resize images

  • Difficulty: Expert
  • Application: bash

Fond of your new camera but can't put up with the terrible names? Do you want also to prepare them for publishing on the web? No problem, a simple bash script is what you need:

#!/bin/sh
counter=1
root=mypict
resolution=400x300
for i in `ls -1 $1/*.jpg`; do
echo "Now working on $i"
convert -resize $resolution $i ${root}_${counter}.jpg
counter=`expr $counter + 1`
done

Save the script in a file called picturename.sh and make it executable with

chmod u+x picturename.sh

and store it somewhere in your path. Now, if you have a bunch of .jpg files in the directory /path/to/pictdir, all you have to do is to execute

picturename.sh /path/to/pictdir

and in the current directory you'll find mypict_1.jpg, mypict_2.jpg etc, which are the resized versions of your original ones. You can change the script according to your needs, or, if you're just looking for super-simple image resizing, try looking at the mogrify command with its -geometry parameter.


#43: Secure logout

  • Difficulty: Easy
  • Application: bash

When you are using a console on a shared machine, or indeed, just on your own desktop, you may find that when you logout, the screen still shows a trace of who was logged in and what you were doing. A lot of distros will clear the screen, but some don't. You can solve this by editing your ~/.bash_logout file and adding the command:

clear

You can add any other useful commands here too.


#44: Transferring files without ftp or scp

  • Difficulty: Easy
  • Application: netcat

Need to transfer a directory to another server but do not have FTP or SCP access? Well this little trick will help out using the netcat utility. On the destination server run:

nc -l -p 1234 | uncompress -c | tar xvfp -

And on the sending server run:

tar cfp - /some/dir | compress -c | nc -w 3 [destination] 1234

Now you can transfer directories without FTP and without needing root access.


#45: Backing up a Debian package list

  • Difficulty: Easy
  • Application: Debian

If you are running Debian and have lost track of which packages you are running, it could be useful to get a backup of your currently installed packages. You can get a list by running:

dpkg --get-selections > debianlist.txt

This will put the entire list in debianlist.txt. You could then install the same packages on a different computer with:

dpkg --set-selections < debianlist.txt

You should bear in mind that you would also need to copy over configuration files from /etc when copying your system to a new computer.

To actually install the selections, use:

apt-get -u dselect-upgrade.


#46: Hardening ssh

  • Difficulty: Easy
  • Application: ssh

Although SSH is a pretty secure way to connect to your server, there are two simple changes you can make that will boost its security even further. First, you almost certainly don't want people logging in directly as root - instead, they should logon as a normal user, then use the su command to switch over. You can change this simply in the /etc/ssh/ssh_config file by adding the line:

PermitRootLogin  no

Now the only way to get root privilges is through su, which means crackers now need to break two passwords to get full access. While you are editing that file, find the line which says:

Protocol 2, 1

And change it to:

Protocol 2

This removes the option to fallback on the original SSH protocol, now considered very vulnerable.


#47: Stop replying to pings

  • Difficulty: Easy
  • Application: sysctl

While ping is a very useful command for discovering network topology, the disadvantage is that it does just that, and makes it easier for hackers on the network to target live servers. But you can tell Linux to ignore all pings - the server simply won't respond. There are a number of ways to achieve this, but the best is to use sysctl. To turn off ping replies:

sysctl -w net.ipv4.icmp_echo_ignore_all=1

To turn it back on, again use:

sysctl -w net.ipv4.icmp_echo_ignore_all=0

If turning off ping is too severe for you, take a look at the next hack.


#48: Slow down ping rates

  • Difficulty: Easy
  • Application: sysctl

You may want to keep the ability to reply to pings, but protect yourself from a form of attack known as a 'ping flood'. So how can you manage such a feat? The easiest way is to slow down the rate at which the server replies to pings. They are still valid, but won't overload the server:

sysctl -w net.ipv4.icmp_echoreply_rate=10

This slows the rate at which replies are sent to a single address.


#49: Clean up KDE on logout

  • Difficulty: Easy
  • Application: bash

On Windows there are plenty of programs that do stuff like clean out your web cache, remove temporary files and all sorts of other stuff when you logout. Wouldn't it be cool to do this on Linux too? With KDE, you don't need to even install any new software, as the startkde script will automatically run scripts you put in special places.

First, you need to create a directory called shutdown in your .kde directory:

mkdir /home/username/.kde/shutdown

Now create a script to do any stuff you like on shutdown. Here is an example:

#!/bin/bash
#clear up temp folder
rm -rf ~/tmp/*
#clear out caches
rm -rf ~/.ee/minis/*
rm -rf ~/.kde/share/cache/http/*
# delete konqueror form completions
rm ~/.kde/share/apps/khtml/formcompletions

Now make sure you set the correct permissions:

chmod ug+x ~/.kde/shutdown/cleanup.sh

(or whatever you called it). As well as cleaning up sensitive files, you can also have global shutdown scripts for all users, by placing the script in your default KDE folder, in a subfolder called shutdown. To find out which is your default KDE directory, try:

kde-config --path exe


#50: Password-less ssh

  • Difficulty: Intermediate
  • Application: ssh

Tired of typing your password every time you log into the server? ssh also supports keys, so you'll only have to type in your password when you log in to the desktop. Generate a keypair on your desktop machine:

ssh-keygen -t dsa -C your.email@ddress

Enter a passphrase for your key. This puts the secret key in ~/.ssh/id_dsa and the public key in ~/.ssh/id_dsa.pub. Now see whether you have an ssh-agent running at present:

echo $SSH_AGENT_PID

Most window managers will run it automatically if it's installed. If not, start one up:

eval $(ssh-agent)

Now, tell the agent about your key:

ssh-add

and enter your passphrase. You'll need to do this each time you log in; if you're using X, try adding

SSH_ASKPASS=ssh-askpass ssh-add

to your .xsession file. (You may need to install ssh-askpass.) Now for each server you log into, create the directory ~/.ssh and copy the file ~/.ssh/id_dsa.pub into it as ~/.ssh/authorized_keys . If you started the ssh-agent by hand, kill it with

ssh-agent -k

when you log out.


#51: Using rsync over ssh

  • Difficulty: Intermediate
  • Application: Shell

Keep large directory structures in sync quickly with rsync. While tar over SSH is ideal for making remote copies of parts of a filesystem, rsync is even better suited for keeping the filesystem in sync between two machines. To run an rsync over SSH, pass it the -e switch, like this:

rsync -ave ssh greendome:/home/ftp/pub/ /home/ftp/pub/

Note the trailing / on the file spec from the source side (on greendome.) On the source spec, a trailing / tells rsync to copy the contents of the directory, but not the directory itself. To include the directory as the top level of what's being copied, leave off the /:

rsync -ave ssh bcnu:/home/six .

This will keep a copy of the ~/six/ directory on village in sync with whatever is present on bcnu:/home/six/. By default, rsync will only copy files and directories, but not remove them from the destination copy when they are removed from the source. To keep the copies exact, include the --delete flag:

rsync -ave ssh  --delete greendome:~one/reports .

Now when old reports are removed from ~one/reports/ on greendome, they're also removed from ~six/public_html/reports/ on the synced version, every time this command is run. If you run a command like this in cron, leave off the v switch. This will keep the output quiet (unless rsync has a problem running, in which case you'll receive an email with the error output). Using SSH as your transport for rsync traffic has the advantage of encrypting the data over the network and also takes advantage of any trust relationships you already have established using SSH client keys.


#52: Asset scanning

  • Difficulty: Intermediate
  • Application: nmap

Normally, when people think of using nmap, they assume it's used to conduct some sort of nefarious network reconnaissance in preparation for an attack. But as with all powerful tools, nmap can be made to wear a white hat, as it's useful for far more than breaking into networks. For example, simple TCP connect scans can be conducted without needing root privileges:

nmap rigel

nmap can also scan ranges of IP addresses by specifying the range or using CIDR notation:

nmap 192.168.0.1-254
nmap 192.168.0.0/24

nmap can provide much more information if it is run as root. When run as root, it can use special packets to determine the operating system of the remote machine by using the -O flag. Additionally, you can do half-open TCP scanning by using the -sS flag. When doing a half-open scan, nmap will send a SYN packet to the remote host and wait to receive the ACK from it; if it receives an ACK, it knows that the port is open.

This is different from a normal three-way TCP handshake, where the client will send a SYN packet and then send an ACK back to the server once it has received the initial server ACK. Attackers typically use this option to avoid having their scans logged on the remote machine.

nmap -sS -O rigel
Starting nmap V. 3.00 ( www.insecure.org/nmap/ )
Interesting ports on rigel.nnc (192.168.0.61):
(The 1578 ports scanned but not shown below are in state: filtered)
Port State Service
7/tcp open echo
9/tcp open discard
13/tcp open daytime
19/tcp open chargen
21/tcp open ftp
22/tcp open ssh
23/tcp open telnet
25/tcp open smtp
37/tcp open time
79/tcp open finger
111/tcp open sunrpc
512/tcp open exec
513/tcp open login
514/tcp open shell
587/tcp open submission
7100/tcp open font-service
32771/tcp open sometimes-rpc5
32772/tcp open sometimes-rpc7
32773/tcp open sometimes-rpc9
32774/tcp open sometimes-rpc11
32777/tcp open sometimes-rpc17
Remote operating system guess: Solaris 9 Beta through Release on SPARC
Uptime 44.051 days (since Sat Nov 1 16:41:50 2003)
Nmap run completed -- 1 IP address (1 host up) scanned in 166 seconds

With OS detection enabled, nmap has confirmed that the OS is Solaris, but now you also know that it's probably Version 9 running on a SPARC processor.

One powerful feature that can be used to help keep track of your network is nmap's XML output capabilities. This is activated by using the -oX command-line switch, like this:

nmap -sS -O -oX scandata.xml rigel

This is especially useful when scanning a range of IP addresses or your whole network, because you can put all the information gathered from the scan into a single XML file that can be parsed and inserted into a database. Here's what an XML entry for an open port looks like:






nmap is a powerful tool. By using its XML output capabilities, a little bit of scripting, and a database, you can create an even more powerful tool that can monitor your network for unauthorized services and machines.


#53: Backup your bootsector

  • Difficulty Expert
  • Application Shell

Messing with bootloaders, dual-booting and various other scary processes can leave you with a messed up bootsector. Why not create a backup of it while you can:

dd if=/dev/hda of=bootsector.img bs=512 count=1

Obviously you should change the device to reflect your boot drive (it may be sda for SCSI). Also, be very careful not to get things the wrong way around - you can easily damage your drive! To restore use:

dd if=bootsector.img of=/dev/hda


#54: Protect log files

  • Difficulty: Expert
  • Application: Various

During an intrusion, an attacker will more than likely leave telltale signs of his actions in various system logs: a valuable audit trail that should be protected. Without reliable logs, it can be very difficult to figure out how the attacker got in, or where the attack came from. This info is crucial in analysing the incident and then responding to it by contacting the appropriate parties involved. But, if the break-in is successful, what's to stop him from removing the traces of his misbehaviour?

This is where file attributes come in to save the day (or at least make it a little better). Both Linux and the BSDs have the ability to assign extra attributes to files and directories. This is different from the standard Unix permissions scheme in that the attributes set on a file apply universally to all users of the system, and they affect file accesses at a much deeper level than file permissions or ACLs.

In Linux, you can see and modify the attributes that are set for a given file by using the lsattr and chattr commands, respectively. At the time of this writing, file attributes in Linux are available only when using the ext2 and ext3 filesystems. There are also kernel patches available for attribute support in XFS and ReiserFS. One useful attribute for protecting log files is append-only. When this attribute is set, the file cannot be deleted, and writes are only allowed to append to the end of the file.

To set the append-only flag under Linux, run this command:

chattr +a  filename

See how the +a attribute works: create a file and set its append-only attribute:

touch /var/log/logfile
echo "append-only not set" > /var/log/logfile
chattr +a /var/log/logfile
echo "append-only set" > /var/log/logfile
bash: /var/log/logfile: Operation not permitted

The second write attempt failed, since it would overwrite the file. However, appending to the end of the file is still permitted:

echo "appending to file" >> /var/log/logfile
cat /var/log/logfile
append-only not set
appending to file

Obviously, an intruder who has gained root privileges could realise that file attributes are being used and just remove the append-only flag from our logs by running chattr -a. To prevent this, we need to disable the ability to remove the append-only attribute. To accomplish this under Linux, use its capabilities mechanism.

The Linux capabilities model divides up the privileges given to the all-powerful root account and allows you to selectively disable them. In order to prevent a user from removing the append-only attribute from a file, we need to remove the CAP_LINUX_IMMUTABLE capability. When present in the running system, this capability allows the append-only attribute to be modified. To modify the set of capabilities available to the system, we will use a simple utility called lcap (http://packetstormsecurity.org/linux/admin/lcap-0.0.3.tar.bz2).

To unpack and compile the tool, run this command:

tar xvfj lcap-0.0.3.tar.bz2 && cd lcap-0.0.3 && make

Then, to disallow modification of the append-only flag, run:

./lcap CAP_LINUX_IMMUTABLE
./lcap CAP_SYS_RAWIO

The first command removes the ability to change the append-only flag, and the second removes the ability to do raw I/O. This is needed so that the protected files cannot be modified by accessing the block device they reside on. It also prevents access to /dev/mem and /dev/kmem, which would provide a loophole for an intruder to reinstate the CAP_LINUX_IMMUTABLE capability. To remove these capabilities at boot, add the previous two commands to your system startup scripts (eg /etc/rc.local). You should ensure that capabilities are removed late in the boot order, to prevent problems with other startup scripts. Once lcap has removed kernel capabilities, they can be reinstated only by rebooting the system.

Before doing this, you should be aware that adding append-only flags to your log files will most likely cause log rotation scripts to fail. However, doing this will greatly enhance the security of your audit trail, which will prove invaluable in the event of an incident.


#55: Automatically encrypted connections

  • Difficulty: Expert
  • Application: FreeS/WAN

One particularly cool feature supported by FreeS/WAN is opportunistic encryption with other hosts running FreeS/WAN. This allows FreeS/WAN to transparently encrypt traffic between all hosts that also support opportunistic encryption. To do this, each host must have a public key generated to use with FreeS/WAN. This key can then be stored in a DNS TXT record for that host. When a host that is set up for opportunistic encryption wishes to initiate an encrypted connection with another host, it will look up the host's public key through DNS and use it to initiate the connection.

To begin, you'll need to generate a key for each host that you want to use this feature with. You can do that by running the following command:

ipsec newhostkey --output /tmp/`hostname`.key

Now you'll need to add the contents of the file that was created by that command to /etc/ipsec.secrets:

cat /tmp/`hostname`.key >> /etc/ipsec.secrets

Next, you'll need to generate a TXT record to put into your DNS zone. You can do this by running a command similar to this one:

ipsec showhostkey --txt @colossus.nnc

Now add this record to your zone and reload it. You can verify that DNS is working correctly by running this command:

ipsec verify
Checking your system to see if IPsec got installed and started correctly
Version check and ipsec on-path [OK]
Checking for KLIPS support in kernel [OK]
Checking for RSA private key (/etc/ipsec.secrets) [OK]
Checking that pluto is running [OK]
DNS checks.
Looking for TXT in forward map: colossus [OK]
Does the machine have at least one non-private address [OK]

Now just restart FreeS/WAN - you should now be able to connect to any other host that supports opportunistic encryption. But what if other hosts want to connect to you? To allow this, you'll need to create a TXT record for your machine in your reverse DNS zone.

You can generate the record by running a command similar to this:

ipsec showhostkey --txt 192.168.0.64

Add this record to the reverse zone for your subnet, and other machines will be able to initiate opportunistic encryption with your machine. With opportunistic encryption in use, all traffic between the hosts will be automatically encrypted, protecting all services simultaneously.


#56: Eliminate suid binaries

  • Difficulty: Intermediate
  • Application: find

If your server has more shell users than yourself, you should regularly audit the setuid and setgid binaries on your system. Chances are you'll be surprised at just how many you'll find. Here's one command for finding all of the files with a setuid or setgid bit set:

find / -perm +6000 -type f -exec ls -ld {} \; > setuid.txt &

This will create a file called setuid.txt that contains the details of all of the matching files present on your system. To remove the s bits of any tools that you don't use, type:

chmod a-s program


#57: Mac filtering Host AP

  • Difficulty: Expert
  • Application: iwpriv

While you can certainly perform MAC filtering at the link layer using iptables or ebtables, it is far safer to let Host AP do it for you. This not only blocks traffic that is destined for your network, but also prevents miscreants from even associating with your station. This helps to preclude the possibility that someone could still cause trouble for your other associated wireless clients, even if they don't have further network access.

When using MAC filtering, most people make a list of wireless devices that they wish to allow, and then deny all others. This is done using the iwpriv command.

iwpriv wlan0 addmac 00:30:65:23:17:05
iwpriv wlan0 addmac 00:40:96:aa:99:fd
...
iwpriv wlan0 maccmd 1
iwpriv wlan0 maccmd 4

The addmac directive adds a MAC address to the internal table. You can add as many MAC addresses as you like to the table by issuing more addmac commands. You then need to tell Host AP what to do with the table you've built. The maccmd 1 command tells Host AP to use the table as an "allowed" list, and to deny all other MAC addresses from associating. Finally, the maccmd 4 command boots off all associated clients, forcing them to reassociate. This happens automatically for clients listed in the table, but everyone else attempting to associate will be denied.

Sometimes, you only need to ban a troublemaker or two, rather than set an explicit policy of permitted devices. If you need to ban a couple of specific MAC address but allow all others, try this:

iwpriv wlan0 addmac 00:30:65:fa:ca:de
iwpriv wlan0 maccmd 2
iwpriv wlan0 kickmac 00:30:65:fa:ca:de

As before, you can use addmac as many times as you like. The maccmd 2 command sets the policy to "deny," and kickmac boots the specified MAC immediately, if it happens to be associated. This is probably nicer than booting everybody and making them reassociate just to ban one troublemaker. Incidentally, if you'd like to remove MAC filtering altogether, try maccmd 0.

If you make a mistake typing in a MAC address, you can use the delmac command just as you would addmac, and it (predictably) deletes the given MAC address from the table. Should you ever need to flush the current MAC table entirely but keep the current policy, use this command:

iwpriv wlan0 maccmd 3

Finally, you can view the running MAC table by using /proc:

cat /proc/net/hostap/wlan0/ap_control

The iwpriv program manipulates the running Host AP driver, but doesn't preserve settings across reboots. Once you are happy with the contents of your MAC filtering table, be sure to put the relevant commands in an rc script to run at boot time.

Note that even unassociated clients can still listen to network traffic, so MAC filtering actually does very little to prevent eavesdropping. To combat passive listening techniques, you will need to encrypt your data.

More info: http://www.tuxradar.com/content/more-linux-tips-every-geek-should-know

Reference: http://tuxradar.com/content/linux-tips-every-geek-should-know


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