- Linux kernel error levels (Value, Name and Meanings)

Error level value	Error level name	Meaning
0	KERN_EMERG	system is unusable
1	KERN_ALERT	action must be taken immediately
2	KERN_CRIT	critical conditions
3	KERN_ERR	error conditions
4	KERN_WARNING	warning conditions
5	KERN_NOTICE	normal but significant condition
6	KERN_INFO	informational
7	KERN_DEBUG	debug-level messages

source:http://linuxpoison.blogspot.com/2010/08/135781677511877.html

- Check your Ubuntu for Non-free packages - vrms (Virtual Richard M Stallman)

In the early 1980's Richard M. Stallman created the GNU project, whose goal was to provide the world with a Free Operating System (with the word "Free" with the same meaning as in "Freedom").

Since then, a lot of Free Software was developed and entire operating systems based only on Free Software were created. Unfortunately, some data is still stored in a format that is proprietary, secret and non-standard, made by corporations that want to retain control over the users of the software that generates such data.

The vrms program provides the facility for users of Debian-based Operating Systems (like Ubuntu Linux) to detect if their systems have any non-free software installed, so that the users can keep their computer "pure", without non-free software.

vrms can be installed using Synaptic Package Manager:

To execute it, just type "vrms" in the terminal and you will get the list of 'non-free' software installed on your system. For each program from 'non-free' installed, vrms displays an explanation of why it is non-free, if one is available. This explanation is usually from a list included in the vrms package itself, but other packages can provide additional lists of explanations, too.

So if you want a completely free (as in freedom!) operating system, you can use Use/ Install gNewsense instead of Ubuntu or others.

source:http://linuxpoison.blogspot.com/2010/08/135781677510925.html

- Graphical network connections viewer for Linux - Netactview

Netactview is a graphical network connections viewer for Linux, similar in functionality with Netstat. It includes features like process information, host name retrieval, automatic refresh and sorting. It has a fully featured GTK 2 graphical interface.

Features:
 * Shows all udp, tcp, udp6 and tcp6 network connections in an automatically refreshed list.
 * The presented information includes protocol names, addresses, ports and connection states along with host names and process information.
 * The connections list can be sorted by any of its columns.
 * Refresh rates ranging from 1/16 to 4 seconds, or no automatic refresh can be selected.
 * Connections can be seen for 3 seconds after they are closed giving you the chance to spot connections that last very little time.
 * The unestablished connections can be filtered out.
 * Multiple connections list snapshots can be saved in a formatted text file.

Installation:
Ubuntu packages (Ubuntu 6.06 or newer)
Standard PC (x86): netactview_0.5.1-1_i386.deb
64bit PC (amd64): netactview_0.5.1-1_amd64.deb

In the standard Ubuntu distribution and other distributions based on Gnome opening the .deb package should start the Gdebi package installer. Gdebi will install the package and all its dependencies.
In KDE based distributions, like Kubuntu, you will have to install Gdebi and open the package with it.

source:http://linuxpoison.blogspot.com/2010/08/135781677512514.html

- Ubuntu Naming Convention

Each Ubuntu release is named in two ways. The official name is the year and month combined, separated by a period. The release made in April 2010 was named 10.04, for example.

Releases also have nicknames, decided upon by Mark Shuttleworth, and humorously derived from types of animals. 8.04 has the nickname Hardy Heron. 8.10 is called Intrepid Ibex. Sometimes the animal component is dropped in formal conversation 8.04 is referred to simply as “Ubuntu Hardy”, or just “Hardy”.

Version    number Nickname    Updated until
4.10          Warty Warthog          April 2006
5.04          Hoary Hedgehog        October 2006
5.10          Breezy Badger           April 2007
6.06          LTS 1 Dapper Drake June 2009
6.10          Edgy Eft                     April 2008
7.04          Feisty Fawn               October 2008
7.10          Gutsy Gibbon            April 2009
8.04          LTS Hardy Heron     April 2011
8.10          Intrepid Ibex             April 2010
9.04         Jaunty Jackalope       October 2010

source:http://linuxpoison.blogspot.com/2010/08/135781677514466.html

- Real-time Bandwidth monitoring tool - Bmon

bmon is a portable bandwidth monitor and rate estimator. It supports various input methods for different architectures. Various output modes exist, including an interactive curses interface, lightweight HTML output, and simple ASCII output. Statistics may be distributed over a network using multicast or unicast and collected at some point to generate a summary of statistics for a set of nodes.

Install bmon
For Ubuntu or Debian systems, either click this link or run the following command in a terminal

$ sudo apt-get install bmon

Using bmon:
Open a terminal and enter the command "bmon" and you should see the following output

Vnstat is the other alternate to bmon - here

source:http://linuxpoison.blogspot.com/2010/08/135781677514951.html

- How to Make Windows Faster than Linux

If you're using Windows and want to make it faster, follow these steps below:

1. Defragment the hard three times a day

2. Remove the antivirus (much consumption)

3. Disable Automatic Updates

4. RAM Upgrade

5. Buy a new CPU

6. Downgrade to Windows 95

7. Wait for Windows 9

More information here

source:http://linuxpoison.blogspot.com/2010/08/135781677515366.html

- How to free Linux Kernel page cache and/or inode and dentry caches

Kernels 2.6.16 and newer provide a mechanism to have the kernel drop the page cache and/or inode and dentry caches on command, which can help free up a lot of memory.

Writing to this will cause the kernel to drop clean caches, dentries and inodes from memory, causing that memory to become free.

To free pagecache:
echo 1 > /proc/sys/vm/drop_caches

To free dentries and inodes:
echo 2 > /proc/sys/vm/drop_caches

To free pagecache, dentries and inodes:
echo 3 > /proc/sys/vm/drop_caches

As this is a non-destructive operation, and dirty objects are not free-able, the user should run "sync" first in order to make sure all cached objects are freed.

source:http://linuxpoison.blogspot.com/2010/08/13578167759254.html

- Creating Fancy and Stylish Screenshots with Screenie

Screenie a small tool to allow you to compose a fancy and stylish screen-shots. It is cross-platform (for Linux, Windows and Mac OS X) and very easy to use. You will have an impressive screen-shot in just one minute!

Screenie Installation:
Ubuntu user can install using synaptic package manger to search and install Screenie

To run,  go to Applications> Graphics> screenie, this with open up three windows: Intructions, screenie-qt and Parameters.

 * The Instructions Windows provides very basic information about using the Screenie.
 * The main window is screenie-qt, where you need to drag and drop the images / screenshots that required makeup (At most we can use three).
 * The Parameters window can be used to change the configuration of the images. For example, distance, angle, opacity, etc.

Below is the example:

source:http://linuxpoison.blogspot.com/2010/08/13578167757154.html

- How to Fix broken package script - Ubuntu

When a command in the package script returns error for some reason and the script exits with error, the package management system aborts their action and ends up with partially installed packages. When a package contains bugs in its removal scripts, the package may become impossible to remove and quite nasty.

For the package script problem of "package_name", you should look for:

/var/lib/dpkg/info/package_name.preinst
/var/lib/dpkg/info/package_name.postinst
/var/lib/dpkg/info/package_name.prerm
/var/lib/dpkg/info/package_name.postrm

You edit the offending part of the script from the root:

by prepending it with "#" or,
by appending it with "|| true". 

Then configures all partially installed packages by: # dpkg --configure -a

source:http://linuxpoison.blogspot.com/2010/08/13578167755813.html

- Configuring a Squid Server to authenticate from MySQL database

Install squid using your distro package management system or using source.
Make sure squid is compiled with --enable-basic-auth-helpers=DB option.

Creating MySQL db/table to hold user credentials
mysql> create database squid;
mysql> grant select on squid.* to someuser@localhost identified by 'your_passwd';

Create table 'passwd' in 'squid' db.

mysql> CREATE TABLE `passwd` (
  `user` varchar(32) NOT NULL default '',
  `password` varchar(35) NOT NULL default '',
  `enabled` tinyint(1) NOT NULL default '1',
  `fullname` varchar(60) default NULL,
  `comment` varchar(60) default NULL,
  PRIMARY KEY  (`user`)
);

Populate the table with some test data, eg

mysql> insert into passwd values('Nikesh','test',1,'Test User','for testing purpose');

Squid Configuration File
Edit squid.conf so that authentication against MySQL db works

auth_param basic program /usr/local/squid/libexec/squid_db_auth --user someuser --password your_passwd --plaintext --persist
auth_param basic children 5
auth_param basic realm Web-Proxy
auth_param basic credentialsttl 1 minute
auth_param basic casesensitive off

acl db-auth proxy_auth REQUIRED
http_access allow db-auth
http_access allow localhost
http_access deny all

Other squid related articles - here

source:http://linuxpoison.blogspot.com/2010/08/135781677519284.html

- The biggest and best collection of wallpapers for Ubuntu

source:http://linuxpoison.blogspot.com/2010/08/135781677519393.html

- Script to add multimedia support to Ubuntu

Ubuntu Multimedia Support Script will add Medibuntu repository and clipgrab ppa and will install the complete multimedia support.

It will install:
- Java Support
- Flash Player Plugin
- Gstreamer Codecs
- w32codecs
- Non-free extra codecs

Instructions:
NOTE: Before continuing, please make sure that all default repositories (exspecially partners' ones) and updates are enabled.

1) Download the script - here
2) Right-click the script you will use, go to proprieties and to the Permissions tab. Select Allow executing as program.Close the window.
3) Now left-click on the script and run it in terminal.

source:http://linuxpoison.blogspot.com/2010/08/13578167753084.html

- How to Hide data (Steganography) into image file - OutGuess

OutGuess is a universal steganographic tool that allows the insertion of hidden information into the redundant bits of data sources. The nature of the data source is irrelevant to the core of OutGuess. The program relies on data specific handlers that will extract redundant bits and write them back after modification. In this version the PNM and JPEG image formats are supported.

This process will allow us to store information of any kind within an image. This can be useful if you intend to send confidential information (such as a text document or a spreadsheet) to a person and do not want such information to be intercepted by someone else (such as the mail provider, a spy, police, etc. ..) We will use the technique of steganography to hide information within the image.

OutGuess Installation:
Ubuntu user can install OutGuess using Synaptic package manager or can install using command:
sudo apt-get install outguess

Data Embedding using OutGues:
Now here is how you do it: you need a text file (in this example we call it "hidden.txt" ) and a picture ( we call it "input.jpg" ) after that you issue the following command to hide your data ("hidden.txt") into the image file.

$ outguess -k "my_passwd" -d hidden.txt input.jpg out.jpg
Reading input.jpg....
JPEG compression quality set to 75
Extracting usable bits:   43283 bits
Correctable message size: 24627 bits, 56.90%
Encoded 'hidden.txt': 1128 bits, 141 bytes
Finding best embedding...
    0:   587(50.6%)[52.0%], bias    68(0.12), saved:    -2, total:  1.36%
   15:   550(47.4%)[48.8%], bias    73(0.13), saved:     1, total:  1.27%
   41:   585(50.4%)[51.9%], bias    32(0.05), saved:    -2, total:  1.35%
  198:   540(46.6%)[47.9%], bias    50(0.09), saved:     3, total:  1.25%
198, 590: Embedding data: 1128 in 43283
Bits embedded: 1160, changed: 540(46.6%)[47.9%], bias: 50, tot: 43059, skip: 41899
Foiling statistics: corrections: 174, failed: 187, offset: 158.255556 +- 316.069419
Total bits changed: 590 (change 540 + bias 50)
Storing bitmap into data...
Writing out.jpg....
$

Data Retrieval
You can retrieve data from an image in the following way:
$ outguess -k "my_passwd" -r out.jpg hidden.txt
Reading out.jpg....
Extracting usable bits:   43283 bits
Steg retrieve: seed: 198, len: 141

source:http://linuxpoison.blogspot.com/2010/08/135781677514136.html