Fedora Linux Legacy Blog

Thursday, July 24, 2008

How To Customize SSH Login Shell Greeting

Network of friends could send greetings to each other by saying any greeting phrases every now and then. Linux shell users and systems admins too could send a greeting messages, daily announcement, scheduled maintenance message or simply a message of the day to power linux shell users every time they visit their linux shell. Greeting shell users with these message could even swept away shell moods and start a good working day.

Here's a quick tip to customize linux message of the day.

Change Linux Message of the Day

Step One

Edit /etc/motd and have something like

====================================================== ##### ####### @ ##O#O## ###### @@# #VVVVV# ## # ## VVV ## ## @@@ ### #### ### ### ##### ###### # ## ## @ @# ### ## ## ## ### ## # ## ## @ @# ## ## ## ## ### # ### ## @@# ## ## ## ## ### QQ# ##Q ## # @@# ## ## ## ## ## ## QQQQQQ# #QQQQQQ ## ## @@# # ## ## ### ### ## ## QQQQQQQ# #QQQQQQQ ############ ### #### #### #### ### ##### ###### QQQQQ#######QQQQQ

rocks...
-powered by IloveTux
======================================================

How To Sort and List The Largest Mailbox User

Being aware of the server's remaining partition's capacity with respect to total account's mailbox usage, particularly with /var partition, is one good practice that brings anybody one step ahead of server disk capacity monitoring and planning. This storage capacity monitoring can be done via web inteface, email alerts or direct from command line terminal.

There are times, you just need to have a quick view of account users occupying the largest portion of your mail partition, just for a quick check. There could be a time when you need to list down the top listing of most mailbox receivers or the currently highest mbox file size from your current terminal.

Here's how to check the top most disk space consuming account user from your linux box

To determine the top list of mailbox user

Go to your mbox partition folder

# cd /var/mail

List down a set of system users with the highest mbox size. This could be using linux ls command with sorting parameter

# ls -lS

The above list down all mbox system users sorted from highest to lowest mbox size.

Now, to list down the top 10 of most active mbox user, simply

# ls -lS | head -10
-rw-rw---- 1 mfeyisola        mail        1899991503 Jul 24 11:35 mfeyisola -rw-rw---- 1 kekechukwu       mail        1783244690 Jul 24 11:34 kekechukwu -rw------- 1 arakoyounian     mail        1620349072 Jul 24 11:41 arakoyounian -rw------- 1 kadaramoye       users       1144226769 Jul 24 11:29 kadaramoye -rw-rw---- 1 conukegbe        mail        1092718167 Jul 24 11:32 conukegbe -rw------- 1 tmoussalli       mail        1087506538 Jul 24 11:41 tmoussalli -rw------- 1 aogiri           mail         878866381 Jul 24 11:42 aogiri -rw------- 1 mobateru         mail         874813665 Jul 24 11:42 mobateru -rw-rw---- 1 jesedebe         mail         820077436 Jul 24 11:33 jesedebe With reverse effect, to list down the least active mailbox system users,

# ls -lS | tail -10

-rw-rw---- 1 rpm       mail     0 2008-07-18 18:15 rpm
-rw-rw---- 1 smmsp     mail     0 2008-07-18 18:16 smmsp
-rw-rw---- 1 squid     mail     0 2008-07-18 18:17 squid
-rw-rw---- 1 sshd      mail     0 2008-07-18 18:19 sshd
-rw-rw---- 1 tcpdump   mail     0 2008-07-18 18:17 tcpdump
-rw-rw---- 1 torrent   mail     0 2008-07-18 18:18 torrent
-rw-rw---- 1 vcsa      mail     0 2008-07-18 18:16 vcsa
-rw-rw---- 1 ver       mail     0 2008-07-18 20:33 ver
-rw-rw---- 1 webalizer mail     0 2008-07-18 18:17 webalizer
-rw-rw---- 1 xfs       mail     0 2008-07-18 18:20 xfs

These commands could be expanded and be integrated with other linux command like awk and grep.

All is done

Wednesday, July 23, 2008

Beyond the Desktop With KDE4

Tectonic: "Lately, there has been quite some bitching on the fringes of the KDE project about KDE4 and the direction it takes. Some people go as far as saying: “Give us back our old desktop!” I beg to differ. The old desktop has served us well for thirty-odd years since its invention by Xerox. It is beyond its due date by now. We need something new that meets the reality we are living in now."

ISO is Being Challenged

Arnaud's Open Blog: "Essentially, the ISO and IEC courts of appeal are made of a jury composed of a subset of the very same parties that judged OOXML in the first place. Now, I’m not a law expert by any means but it doesn’t take much expertise to figure out that such a set up is bogus."

Beyond the Desktop With KDE4

ISO is Being Challenged

How To Repeat Previous Command Line Argument With KeyStroke

With hundreds of linux terminal command lines being saved to shell history file, a good practice of repeating old and previous command line command and argument is another convenience we could make use of.

By realizing a mistake from a recently issued linux command like

# vi /usr/share/wordpress/wp-content/themes/vertito/images/imgs/

could be tiresome specially if the linux command parameter is longer 50 characters.

One approach to tackle this scenario is by simply hitting the ketboard's Up Arrow Key to repeat the previously issued linux command. This Up Arrow keystoke, when pressed inside a shell environment, repeats the previously issued command taken from the keystroke command buffer ring. The problem with using this shortcut keystroke is that it cycles back to previously issued wrong linux command or command with wrong parameter. Tendency is you hit more keystroke combinations to edit the command, say Control + A to begin editing the first few letters of the command or Control + E to modify the last portion of the command.

If you want to repeat the recently issued command line parameter from the previously issued command, you can use this approach.

Say, to list down directory contents of a folder, we issue the below command by mistake

# vi /usr/share/wordpress/wp-content/themes/vertito/images/imgs/

But our intention is to list down the files and directory on that folder. This basically means we need to retype the parameter, or do the Up Arrow key to repeat the previously issued command. Here's another alternative to accomplish the same task.

# ls -la !*

!* combination repeats the last supplied command with the previous command.

All is done

Tuesday, July 22, 2008

HowTo: Install 113 Amazing Fedora Games Part 5

Continuation...

SuperTuxKart
3D go-kart racing game for kids with several famous OpenSource mascots participating. Race as Tux against 3 computer players in many different fun race courses (Standard race track, Dessert, Mathclass, etc). Full information on how to add your own race courses is included. During the race you can pick up powerups such as: (homing) missiles, magnets and portable zippers.

# yum install supertuxkart

NeverBall
Tilt the floor to roll a ball through an obstacle course within the given time. If the ball falls or time expires, a ball is lost. Collect 100 coins to save your progress and earn an extra ball. Red coins are worth 5. Blue coins are worth 10.

# yum install neverball

Flight Gear
The Flight Gear project is working to create a sophisticated flight simulator framework for the development and pursuit of interesting flight simulator ideas. We are developing a solid basic sim that can be expanded and improved upon by anyone interested in contributing.

# yum install FlightGear

Penguin-Command
Penguin Command is a clone of the classic "Missile Command" Game, but it has better graphics and music. The gameplay has only been slightly modified. Penguin Command is licensed under the GPL.

# yum install penguin-command

Crack Attack
A puzzle/action game in which you rush to eliminate colored blocks before they fill your screen. Particularly clever eliminations cause garbage to clutter your opponent's screen. Who will survive the longest!? Playable both online and off.

# yum install crack-attack

Clan Bomberman
ClanBomber is a free (GPL) Bomberman-like multiplayer game that uses ClanLib, a free multi platform C++ game SDK. First "ClanBomber" was only a working title for a small game started in September 1998, that has only been started to learn how to use ClanLib. But the ClanBomber project has grown into a real game. It is fully playable and features Computer controlled bombers, however, it is recommended to play ClanBomber with friends (3-8 players are really fun).

# yum install clanbomber

Penguin PRacer
PPRacer is a simple OpenGL-based racing game featuring Tux. The objective of the game is to slide down a snow- and ice-covered mountain as quickly as possible, avoiding the trees and rocks that will slow you down.

# yum install ppracer

Tremulous
Tremulous is a free, open source game that blends a team based FPS with elements of an RTS. Players can choose from 2 unique races, aliens and humans. Players on both teams are able to build working structures in-game like an RTS. These structures provide many functions, the most important being spawning.
The designated builders must ensure there are spawn structures or other players will not be able to rejoin the game after death.
Other structures provide automated base defense (to some degree), healing functions and much more...

# yum install tremulous

FreeCiv
Freeciv is a turn-based, multi-player, X based strategy game. Freeciv is generally comparable to, and has compatible rules with, the Civilization II(R) game by Microprose(R). In Freeciv, each player is the leader of a civilization, and is competing with the other players in order to become the leader of the greatest civilization.

# yum install freeciv

Glest
Glest is a free 3D real time strategy game, that can be modified using XML and a set of tools. Glest takes place in a context which could be compared to that of the pre-renaissance Europe, with the licence that magic forces exist in the environment and can be controlled.

# yum install glest

Duel3 - 2D SpaceShip Duel
The sudden attack from the Martain Rim miners caught the Earth by suprise, there was no way the meager Earth Space Fleet could defend themselves. The miners attacked, and eliminated their enemies, and then returned to the asteroid belt. However, Earth could not accept such an embarrassing defeat. The military developed new space fighters, and trained several squadrons of elite pilots. The task force was then deployed against the miners. These trained pilots utterly defeated the miners in a matter of weeks, and the first space war in human history was finished.

# yum install duel3

XMoto - 2D MotoCross Platform Game
X-Moto is a challenging 2D motocross platform game, where physics play an all important role in the gameplay. You need to control your bike to its limit, if you want to have a chance finishing the more difficult of the challenges. First you'll try just to complete the levels, while later you'll compete with yourself and others, racing against the clock.

# yum install xmoto

r />

XMoto Level Editor
# yum install xmoto-edit

Continue here.

Linux Scorched 3D Tank Game

Meet Scorched 3D Classic Tank Game.

Scorched 3D is another classic 3D linux tank game that is based on a DOS game polished with more features such as OpenGL supported, multiple player and weapon options, more landscape island war environment spots, LAN-enabled enemies, save and retrieve game levels and more. Scorched 3D tank game can be played by stand-alone or online.

Man Scorched 3D:
Scorched 3D is a game based on the classic DOS game Scorched Earth "The Mother Of All Games". Scorched 3D adds amongst other new features a 3D island environment and LAN and internet play. At its lowest level, Scorched 3D is just an artillery game with two+ tanks taking turns to destroy opponents in an arena. Choose the angle, direction and power of each shot, launch your weapon, and try to blow up other tanks. But Scorched 3D can be a lot more complex than that,
if you want it to be. You can earn money from successful battles and use it to invest in additional weapons and accessories. You can play with up to twenty four other players at a time, mixing computer players with humans. There's a variety of changing environmental conditions and terrains to be dealt with.

Scorched 3D is totally free and is available for both Microsoft Windows and Unix (Linux, FreeBSD, Mac OS X, Solaris etc.) operating systems.

You can pick up the game and begin playing very quickly. Then, when/if you are interested, you can poke in the dimmer recesses of the game and get into the strategy (or just ignore it altogether!).

The main objective of the game is to stand from the rest of the enemy tanks. Last tank standing wins.

Visit Scorched 3D tank game from here.

INSTALLATION MADE EASY

Scorched 3D is available from Fedora Project repos. Thus, the tank game can be installed via yum.
From Fedora 8, simply issue the following yum command for installation.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# yum -y install scorched3d
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The above command will install the necessary dependencies including non-installed opengl package. Yum would download an approximately 60 MB of package files.

Screenshots

More wiki documents can be found from here and mods are widely available from here.

Goodluck and enjoy tank-scorching!

HowTo: Install YouTube Video Download in Fedora

This quick post should have been here since but I keep on forgetting about this quick howto.

Download Videos from Youtube from Fedora box

Tired of watching and browsing the same old video files from Youtube? Do you wish to collect Youtube video clips of your favorite video files from youtube? Now, you can do it inside your Fedora box. If you wish to download video clip files from YouTube.com into your desktop, read on.

Youtube Download Installation

Simply install youtube video downloader called Youtube-dl. Youtube downloader is a command line-driven linux tool designed to download youtube videos into your desktop, you got it right. Download youtube videos from youtube into your Fedora box.

Simply folow this yum installation

# yum -y install youtube-dl

Youtube-Dl Usage

The video clip shown below is one of the fastest one-handed rubix cube solver that solves rubix cube in less than 18 seconds as you can see.

Now, if you with to download the above video using youtube video downloader, simply

# youtube-dl http://www.youtube.com/watch?v=vnRJROskpp4

File output would be saved as vnRJROskpp4.flv file format.

Play Youtube Video from your Desktop

To play video file from youtube, simply follow the vlc install procedures from here.
# youtube-dl http://www.youtube.com/watch?v=2BA9om9iy0c

Alternatively, you can use a browser to download youtube videos from here.

Enjoy viewing youtube video from your desktop!

Non-Related Articles:
Real-Time 3D Earth Visualization
3D Earth and Sky Visualization
Scorched 3D Tank Game
3D Table Lawn Tennis Game
Warzone 3D Strategy Game
113 Amazing Fedora Games

How To Beat A Computer Opponent in KSquares Linux Game

Playing KSquare game allows you to put a single stick to connect into group of squared patterns presented in a matrix type of columns and rows. This KSquare game allows you to have a single move at a time alternating each turns. Each time you drop a stick into the matrix, your opponent tries to check and see if a possible square can be formed from your last move.

The rules with KSquare is simple, regardless of how many rows and columns of square patterns the game has, the highest squares formed by a player wins.

KSquare is fairly easy to beat. The trick is to establish a fallback move-trap wherein your opponent will be forced to lay down his stick to a location where the least square could be formed. This trap is a must for both players as when the game gets touch, both players have the chance to use those multiple fall back traps to his advantage. The after effect of this fall back trap is for the opponent to complete his turn with the fall back trap and continue laying out a stick into the matrix providing you a turn to form higher number of squares. This approach would definitely beat a computer opponent.

Here's a simple screenshot of a computer opponent being defeated.

As you can see, there are two sets of fallback traps, one with a higher chance of gaining squares compared to the other one, which has only 4 possible squares to complete. The red player wins the game as you can see.

KSquare does not need more of keyboard action moves, and point and shoot skills - it simply needs a basic skill set to estimate an opponent's possible move but much more simpler than playing chess.

All is done.

How To Do FTP File Operations without Graphical FTP Client

On small and medium scale server environment, most linux servers are not equipped with X (GNOME/KDE) graphical platform that makes the task of uploading and downloading FTP files to and from your current location a much more easier task. Consider a robust FTP client software equipped with user-friendly and graphical menu interface to upload/download FTP files could offer a much more convenient and easier process to accomplish FTP file operations compared to command-line driven FTP commands.

What do you do if your linux system does not support graphical X11 programs? What steps you can follow from your linux desktop without X to process FTP task into your FTP server? Here's a quick entry on how to accomplish that.

Download and Upload FTP Files from Command Line Terminal

Minimum Requirements

1. Existing FTP server
2. Existing FTP user account details

Step One

Connect and log on to your FTP server from terminal. Supply the required FTP username and password.

# ftp domain.com

Launching the above command would give you similar lines as shown below

Connected to domain.com (83.83.83.83).
220---------- Welcome to Pure-FTPd [TLS] ----------
220-You are user number 2 of 50 allowed.
220-Local time is now 03:32. Server port: 21.
220-This is a private system - No anonymous login
220 You will be disconnected after 15 minutes of inactivity.
Name (domain.com:root): ftpuser
Password: *******
230-User ftpuser has group access to: ftpuser
230 OK. Current restricted directory is /
Remote system type is UNIX.
Using binary mode to transfer files.

Now, the last line showed that the curent binary mode of file transfer is binary. You can optionally modify this value.

To change FTP file transfer mode to ASCII

To transfer all ASCII file types, simply

ftp> ascii

To change FTP file transfer mode to binary

ftp> bin

Step Two

Identify your current local and remote directory location.

To change your current local directory
ftp> lcd /home/user1
Local directory now /home/user1

To change your current FTP directory folder

ftp> cd www
250 OK. Current directory is /www

To list down all remote FTP files from current directory location

ftp> ls
# ls *.html
# ls *.php

Alternatively, you can use dir

ftp> dir
ftp> dir *.php

When transferring files, by default configuration, the current file transfer status is now shown. You could setup your current connection to shown you current command status and even send you a beep when the last issue FTP command has been completed.

To show FTP file transfer status for file transfer

ftp> hash

To toggle hash status, simply re issue hash command again.

To send alert on FTP command completion

ftp> bell
Step Three

Now that your current local and remote location have been identified, you can now begin your FTP file transfer

To upload a file from local to remote FTP server

ftp> put filename.txt
ftp> put filename.php

To upload multiple files to remote FTP server

ftp> mput *.php

To confirm file changes from remote, simply re issue a directory listing command

ftp> ls

To download FTP files into your local folder

ftp> get filename.txt

To download multiple FTP files from terminal

ftp> mget *.php

To disconnect from FTP connection

ftp> bye
ftp> quit

221-Goodbye. You uploaded 0 and downloaded 1 kbytes.
221 Logout.

The total number of uploaded and download FTP files will be shown to you when disconnecting from FTP server as shown above.

For more ftp commands, issue

ftp> help
All is done.

Monday, July 21, 2008

How To Limit Denial of Service Attacks to Sendmail

Whenever a sendmail receives SMTP request and connection from a remote host, it spawn's a new copy of itself to deal with incoming mail messages. This approach makes it useful for sendmail to process multiple incoming mails simultaneously. However, the nature of linux application always comes with a trade off thing. This issue of spawning another sendmail daemon child would consume another portion of system and thus could hogged down your email server.

Considering the openness of email address nature, an email bomber could launch a malicious flood attack to an email server with bunch of emails for delivery that could easily be done automatically using automated software. This scenario could cause sendmail denial of service.

The below sendmail directives option could restrict and limit the number of sendmail children to spawn, limit the number of connections to receive per second, restrict sendmail process incoming header size, and lastly, limit the maximum acceptable size of one message. By setting this sendmail directive, the effectiveness of such denial of sevice attack to sendmail could be limited and/or delayed.

Sendmail Directives

confCONNECTION_RATE_THROTTLE

This is number of connections sendmail server can receive per second. By default rpm installation, Sendmail does not limit the number of connections per second it can receive. If the value configured here is set and reached, any further connections are then delayed.

confMAX_DAEMON_CHILDREN

This is the number of child processes that can be spawned by the server, or refers to sendmail children. By default rpm installation, Sendmail does not define a limit to the number of spawned child daemon. If this limit is reached, further connections are also delayed.

confMIN_FREE_BLOCKS

This is the minimum number of free blocks is available for sendmail server when accepting mails. The default is 100 blocks. Once the value specified with this sendmail directive is reached, sendmail is instructed to stop accepting mails.

confMAX_HEADERS_LENGTH

This is the maximum acceptable size (in bytes) of an email's message header. Any email message headers that reached this limit would not be accepted and denied from being queued for delivery.

confMAX_MESSAGE_SIZE

Limiting the the maximum acceptable size (in bytes) of an email message could also limit the possible attachment bomb attack against sendmail server. Implementing a maximum message size could set a limit to email message maximum size. An example sendmail.mc entry would likely be\

confMAXRCPTSPERMESSAGE

This is the number of recipients per message. Limiting the maximum recipient one email message could have could restrict any email bomber trying to send an email to multiple recipients.

A sample entry of the above directive would be

define(`confMAX_DAEMON_CHILDREN', 10)
define(`confMAX_HEADERS_LENGTH', `32768')
define(`confMAX_MESSAGE_SIZE', 10000000)
define(`confMIN_FREE_BLOCKS',`3000')
define(`confCONNECTION_RATE_THROTTLE', `3')
define(`confMAXRCPTSPERMESSAGE', `30')

To implement the above sendmail directive, simply backup and modify your /etc/mail/sendmail.mc and recompile it again. For the changes to take effect, simply restart your sendmail service like so

# vi /etc/mail/sendmail.mc
# m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf
# service sendmail restart

All is done.

How To Support Compressed RAR File Types in Fedora

This entry aims to address file handling of RAR file types. If you are receiving this type of files from your inbox, you can configure your fedora linuxsystem to support RAR compressed file types.

Fedora repository supports rpm package designed to handle and uncompressed RAR file types via unrar rpm package.

UnRAR Installation - Support RAR File Types in Fedora Linux

Unrar rpm package is supported by Fedora repository.

To install unrar rpm package, simply

# yum -y install unrar

To Extract Compressed RAR Files

# unrar example.rar /home/user

The above would extract files inside the compressed RAR file example.rar into /home/user as its destination extraction directory.

To Extract RAR Files to Current Directory

# unrar e example.rar

To List All Archived Files inside RAR File

# unrar l example.rar

The above command would only list out the files inside the compressed RAR files.

To Verbosedly Extract RAR files with Full Path

# unrar xv example.rar

To convert output filenames into lowercase or uppercase filename using unrar, simply

For lowercase filename output conversion using unrar

# unrar cl example.rar

For uppercase filename output conversion using unrar

# unrar cu example.rar

To unrar files with specific file size like files with less than or more than specific file size,

For less than unrar usage

# unrar sl<size>

For more than unrar usage

# unrar sm<size>

Unrar supports many command line parameter, you can see its man page

# man unrar

All done.

How To Make Use of UMask

Changing file permission is a file security thing. Any file owned by another user with improper file permissions could grant file access for free to any system users. This could also lead to super user access to the whole operating system in the case of improper default umask value with shadow and password files.

Introducing Umask

Umask is a system environment variable which is used for setting default file permissions on operating system. Umask can be configured with a system wide default value automatically or on per user basis.

Umask Usage

Umask usage with with file and directories has different value. To determine specific umask values, use a simple arithmetic procedure with the common umask value for file, which is 666 and 777 for directories.

Say, if you want all newly files to be created with file permissions of 660, set your umask to 006. That is 666 minus (-) determined file permission of 660 would equal to 006.

Alternatively, to set for a reasonable default file permission value of 644 would need a umask value of 022. This will cause files to be created with default permissions of 644 , that is (rw-r--r--) file permission set.

For directory permission, you could subtract 777 umask common value. Say, a desired directory permission of (rwxrwx---) 770 would need a umask value of 007.

For paranoid secure value, a default umask value of 066 would create new files with 600 (rw-------) and directories with permissions of 700 (rwx-----) .

Determine System Umask Value

Issue umask without any parameters

# umask

System-wide Umask Setting
The default umask value for system wide configuration can be viewed inside your /etc/bashrc file.

Per-User Umask Value Setting

To set a per-user settings with umask, simply backup and modify a user's .bashrc file located from the user's default home directory. Make sure that your specific user's umask value is appended to the last line of the the said .bashrc file.

Save and exit. Changes would take effect on new login shells and file/directory creations.

How To Install An Alternative Lightweight Graphical Browser

The thing with browsers nowadays is the more you equip it with addons, plugins, and powerpack browser features, the heavier the load it gets and the slower your PC desktop runs. You could find a lot of browser tweaks and hacks to make your browser faster and works quicker than its default setup, what goes down the drain is how much memory footprints does your browsers take? With or without browser optimizations, tweaks and hacks, there should be an approximate value how much does your browser consumes up with your desktop memory. If you want to install an alternative lightweight graphical desktop, read on.

Introducing Kazehakase

Kazehakase is a graphical web browser which aims to provide a very simple graphical user interface that is truly user-friendly and fully customizable. Kazehakase uses Gecko for rendering HTML pages like Galeon and Epiphany. Here are its main features.

Tabbed Browsing

Bookmarks

Variable Toolbars

Customizable mouse gestures

Customizable key accelerator

Print Support

How To Install Kazehakase on Fedora

# yum -y install kazehakase

# kazehakase

If you will browse heavy sites like CNN or Yahoo!, kazehakase is not for you as those mentioned sites would require the latest flash and java versions not allowing you to proceed browsing the site.

You can visit more of Kazehakase project here.

Saturday, July 19, 2008

How To Increase Squid's Cache Directory Swap Size

At times, granted a high-end server capacity and resources with large disk and memory capacity, increase squid's disk cache size is highly adviseable. With higher disk cache size, you provide a higher amount of disk space to be used by squid on caching web files.

Increase Squid Cache Directory Swap Size

With default Squid rpm installation, the default value of squid cache directory swap size is set to 100MB. Having a large disk storage would be efficient to store a larger directory swap size for squid to use.

Simply edit /etc/squid/squid.conf and find the cache directory squid directive

cache_dir ufs /var/spool/squid 100 16 256

/var/spool/squid is the directory folder location where squid will use to swap cached web files.

100 The first number is the amount of disk space in MB to be used by squid for caching directory.

16   is the number of first-level subdirectories which will be created under the 'Directory'.

256 is the number of second-level subdirectories which will be created under each first-level directory.

To verify your disk and partition sizes, simply

# df -ah

giving you a similar lines

/dev/sda3              49G 4.5G   42G 10% /var
/dev/sda2             387G   18G 350G   5% /home
/dev/sda1              99M   12M   83M 13% /boot

From default squid installation, cache dir is physically dumped to /var directory by default.

Now, considering a server with high space, say 40GB free disk partition size, you could reconfigure squid cache_dir to a value of

cache_dir ufs /var/spool/squid 2000 32 512

That is 2GB of cache directory for squid to use with 512 second-level directory under the first level of 32.

Save, exit and create the cache directory.

Stop Squid first

# service squid stop

Recreate Squid Cache Directory

# squid -z

Start Squid Service

# service squid start

This setup would nicely suit a large and regular internet user infrastructure setup.

All done.

How To Limit Outgoing Email Recipient Using Sendmail

This sendmail directive implements the number of allowed recipients of each email message. One signature of an email spammer is delivering an email to thousands and hundreds of recipients all at the same time. This sendmail directive prevents that.

MAX_RCPTS_PER_MESSAGE

If an email message comes with more than the allowed number of recipients per message, the excess recipients are stripped out and are rejected but the ones under the limit are accepted and get delivered. This sendmail directive limit applied to outgoing message only.

In other cases of sendmail setup, say a famous social networking site would need a higher max_rcpts_per_message limit. You could decrease the value to a minimum number that suits your needs.

Configure Sendmail for Maximum Email Recipient Limit

Simply backup and edit /etc/mail/sendmail.mc and add the confMAXRCPTSPERMESSAGE sendmail directive as shown below. Say, to define a maximum limit of 30 email recipients would similarly be like

define(`confMAXRCPTSPERMESSAGE', `30')dnl

Note that with some current webmail features, as soon as the maximum recipient is reached, a denied SMTP connection is immediately rejected and denied.

If your company setup define a little less than 30 staff with less email rate activity, you could decrease that to a very minimum level.

Second Life: A Wide World for Med, Science Students

Judith Kung Fu may be just one of more than 14 million computer-generated characters in the 3-D virtual world Second Life. But with her help, her creator may one day save your life. In Second Life, Judith has walked through the walls of a human cell. She has, in a flash, conducted complicated science experiments that took the world's best minds years to complete. She has helped her creator, 21-year-old Jacqueline Rodriguez, a senior biology major at Texas Wesleyan University, take crucial steps toward becoming a doctor...

Complete Story

SCO to Cough Up $2.5M for Novell's Unix Royalties

A federal judge ruled Wednesday that The SCO Group must pay more than $2.5 million in royalties to Novell for licensing the Unix computer operating system software to Sun Microsystems. The decision by U.S. District Judge Dale Kimball in Salt Lake City came in the long-running dispute between Novell of Provo, Utah, and SCO. In 2007, Kimball ruled Novell still owned pre-1995 copyrights to the Unix system that it sold that year to The Santa Cruz Operation. Lindon, Utah-based SCO bought the system in 2001 from Santa Cruz...

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Play Ogg! Support media formats that support freedom...

Are you fed up with seeing new gadgets that only use incompatible and restrictive audio and video formats? Did you know that it's not a lack of technological know-how that causes this, but software patents and other legal restrictions?What's the solution? Play Ogg!..

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A Chat With Mr. Linus Torvalds, Father of the Linux OS

Q: "Which Linux distro do you use?" A: "I've used different distributions over the years. Right now I happen to use Fedora 9 on most of the computers I have, which really boils down to the fact that Fedora had fairly good support for PowerPC back when I used that, so I grew used to it. . ."..

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Ubuntu hits new high in Linux boredom

Last weekend a friend was moaning about endless problems with Windows XP on his desktop PC. We installed Ubuntu 7.04 on it. The problems went away. That started me thinking about my own "daily driver" computer, a Dell Latitude that also runs Ubuntu 7.04, and it made me realize that I hadn't thought about my laptop or its operating system in many months. Linux -- especially Ubuntu -- has become so reliable and simple that for most end users it's simply not worth thinking about, any more than we think about tools like wrenches and screwdrivers. Does this mean desktop GNU/Linux has become so boring that it's not worth noticing?
..

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Jump start your Web app deployment with a JumpBox

Software installation, deployment, and configuration can be a headache and a time sink for systems administrators. To ease the process, JumpBox delivers preconfigured Web apps that run as virtual appliances on any machine, across platforms, irrespective of operating system.
..

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Second Life: A Wide World for Med, Science Students

Judith Kung Fu may be just one of more than 14 million computer-generated characters in the 3-D virtual world Second Life. But with her help, her creator may one day save your life. In Second Life, Judith has walked through the walls of a human cell. She has, in a flash, conducted complicated science experiments that took the world's best minds years to complete. She has helped her creator, 21-year-old Jacqueline Rodriguez, a senior biology major at Texas Wesleyan University, take crucial steps toward becoming a doctor...

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SCO to Cough Up $2.5M for Novell's Unix Royalties

A federal judge ruled Wednesday that The SCO Group must pay more than $2.5 million in royalties to Novell for licensing the Unix computer operating system software to Sun Microsystems. The decision by U.S. District Judge Dale Kimball in Salt Lake City came in the long-running dispute between Novell of Provo, Utah, and SCO. In 2007, Kimball ruled Novell still owned pre-1995 copyrights to the Unix system that it sold that year to The Santa Cruz Operation. Lindon, Utah-based SCO bought the system in 2001 from Santa Cruz...

Complete Story

Play Ogg! Support media formats that support freedom...

Are you fed up with seeing new gadgets that only use incompatible and restrictive audio and video formats? Did you know that it's not a lack of technological know-how that causes this, but software patents and other legal restrictions?What's the solution? Play Ogg!..

Complete Story

A Chat With Mr. Linus Torvalds, Father of the Linux OS

Q: "Which Linux distro do you use?" A: "I've used different distributions over the years. Right now I happen to use Fedora 9 on most of the computers I have, which really boils down to the fact that Fedora had fairly good support for PowerPC back when I used that, so I grew used to it. . ."..

Complete Story

Ubuntu hits new high in Linux boredom

Last weekend a friend was moaning about endless problems with Windows XP on his desktop PC. We installed Ubuntu 7.04 on it. The problems went away. That started me thinking about my own "daily driver" computer, a Dell Latitude that also runs Ubuntu 7.04, and it made me realize that I hadn't thought about my laptop or its operating system in many months. Linux -- especially Ubuntu -- has become so reliable and simple that for most end users it's simply not worth thinking about, any more than we think about tools like wrenches and screwdrivers. Does this mean desktop GNU/Linux has become so boring that it's not worth noticing?
..

Complete Story

Jump start your Web app deployment with a JumpBox

Software installation, deployment, and configuration can be a headache and a time sink for systems administrators. To ease the process, JumpBox delivers preconfigured Web apps that run as virtual appliances on any machine, across platforms, irrespective of operating system.
..

Complete Story