April 2009 | Linux Blog

Iptraf - Ncurses based LAN monitor

IPTraf is a network monitoring utility for IP networks. It intercepts packets on the network and gives out various pieces of information about the current IP traffic over it. Information returned by IPTraf include:

    * Total, IP, TCP, UDP, ICMP, and non-IP byte counts
    * TCP source and destination addresses and ports
    * TCP packet and byte counts
    * TCP flag statuses
    * UDP source and destination information
    * ICMP type information
    * OSPF source and destination information
    * TCP and UDP service statistics
    * Interface packet counts
    * Interface IP checksum error counts
    * Interface activity indicators
    * LAN station statistics

IPTraf can be used to monitor the load on an IP network, the most used types of network services, the proceedings of TCP connections, and others.

Installation:
OpenSuSe 11.1 - here
OpenSuSe 11.0 - here

Others:
Download the latest version. Once you have it downloaded, move it to /usr/local/src and untar it by running: # tar -zxvf iptraf-3.0.0.tar.gz

To compile and install, just change to the iptraf-3.0.0 top-level directory and type:./Setup
This will automatically compile and install the software and install the binaries into /usr/local/bin so make sure that directory is in your PATH.

The traditional way to do it ..

        cd src
        make clean
        make
        make install

Precompiled binaries are available in the iptraf-3.0.0.i386.bin.tar.gz file. This contains no source code and is expected to run on Intel x86 Linux with the GNU C Library 2.1 or later.

Once you have it installed, start it up by typing /usr/local/bin/iptraf as root. An ncurses based main menu will come up on your screen and you will have a list of options that you can select.

ntop (Monitor Network Traffic) installation/configuration on OpenSuSe

ntop is a network traffic probe that shows the network usage, similar to what the popular top Unix command does. ntop is based on libpcap and it has been written in a portable way in order to virtually run on every Unix platform and on Win32 as well.

ntop users can use a a web browser (e.g. Firefox) to navigate through ntop (that acts as a web server) traffic information and get a dump of the network status. In the latter case, ntop can be seen as a simple RMON-like agent with an embedded web interface. The use of:

    * a web interface
    * limited configuration and administration via the web interface
    * reduced CPU and memory usage (they vary according to network size and traffic)

make ntop easy to use and suitable for monitoring various kind of networks.

To run ntop you also require rrdtool, if not install, install it : # yast2 -i rrdtool rrdtool-devel

Installation: Use "1-click" installer to install ntop
OpenSuSe 11.1 - here
OpenSuSe 11.0 - here

Once the installation is successfully completed run ntop -A (as a root user) for the first time to set the password for the default ntop admin user (admin).

Now go to /etc/sysconfig/ntop config file and make the necessary changes like web interface (NTOPD_PORT="127.0.0.1:3000") and ethernet card (ip address) on which you want to monitor your network traffic like eth0, something like ....

After making all the necessary changes just restart the ntop server: # /etc/init.d/ntop restart and go to you web browser and point to: http://localhost:3000 to see network traffic flowing in and out of your network, something like ...

React Operating System - Another Windows in making

ReactOS is a free, modern operating system based on the design of Windows XP/2003. Written completely from scratch, it aims to follow the Windows architecture designed by Microsoft from the hardware level right through to the application level. This is not a Linux based system, and shares none of the unix architecture.

The main goal of the ReactOS project is to provide an operating system which is binary compatible with Windows. This will allow your Windows applications and drivers to run as they would on your Windows system. Additionally, the look and feel of the Windows operating system is used, such that people accustomed to the familiar user interface of Windows would find using ReactOS straightforward. The ultimate goal of ReactOS is to allow you to remove Windows out of your window and install ReactOS without the end user noticing the change.

ReactOS is licensed under the GNU General Public License.

More such screenshots - here

Ubuntu 9.04 - Jaunty Jackalope CD Labels

Excellent cover for your CDs Jaunty.
It also included the SVG so you can edit it if it doesn't fit your CD's (larger middle hole).

There are covers also available for:
    * Ubuntu SVG
    * Ubuntu 32 bits Desktop
    * Ubuntu 32 bits Alternate
    * Ubuntu 32 bits Server
    * Ubuntu 64 bits Desktop
    * Ubuntu 64 bits Alternate
    * Ubuntu 64 bits Server
    * Kubuntu SVG Kubuntu SVG
    * Kubuntu 32 bits Desktop
    * Kubuntu 64 bits Desktop

Download it from -- here

Voice Control your Ubuntu desktop

Gnome-Voice-Control is a dialogue system to control the GNOME Desktop. It is developed on Google Summer of Code 2007.

The idea is to develop some features that will improve the usability in the Gnome Desktop (Ubuntu). The goal is to implement a Desktop Voice Control System. The system consists in an application that will be monitoring the audio input(microphone) and when a significant audio signal has been detected, the software catches, processes and recognizes the signal and then executes the desired action over the Gnome Desktop. In a set of actions could include maximize, minimize, close the active window; open a specific program; switching from one desktop to another; among others. GnomeVoiceControl is implemented in C in conjunction with CMU Sphinx, which is an open source tool, created to convert speech to text.

If you'd like to have a quick start, look at screencast below .

Install it from the terminal:

sudo aptitude install gnome-voice-control

The installation and configuration is simple. To use you have to right click on a panel (the bar on the desktop) and add the applet "VoiceControl", and using this applet you can start and stop the use of voice control application.

For now the application is in its initial stage but can do everything like ...

Next Window
Minimize Window
Maximize Window
Close Window

Run Terminal
Run Text Editor
Run Mail

List of Repositories for Ubuntu 9.04 Jaunty Jackalope

Multimedia Support in Ubuntu 9.04 Jaunty Jackalope

Latest free Ubuntu Linux operating system version is officially released today. Ubuntu 9.04 for desktop, server and “netbook remix” is available for immediate download, CD purchase or you can request a free CD.

Ubuntu is a free operating system that can be used on desktop PCs, notebooks, work/business PCs as well as other devices that support either the x86 CPU or ARM CPUs (beginning with version 9.04, previous versions only supported x86). It is a version of Linux that includes a graphical desktop.

Often the case (and especially) when it comes out a new version of Ubuntu, that repositories from which we tend to download software are highly saturated. If you want to download and install the software more quickly, we will have to modify the list of repositories.

There is an option to Synaptic, which allows us to select a server closest to our region. To change this to a server closest go to System> Administration> Origins of software under the tab "Software Ubuntu", choose "download".

Install the software basics of compilation
If you want to compile some of the package that only have the source code, in this case we need to install packages basic Basic compilation:

    sudo aptitude install build-essential

Installing the extra restrictive.
There are certain packages that do not come by default in Ubuntu for legal issues. for example, may be the plug-in flash, or codecs to be able to play some video formats. There is a metapackage (a package that includes many more packages and installs) called ubuntu-restricted-extras that can install all the required restricted packages.

    sudo apt-get install ubuntu-restricted-extras

Repository for mediubuntu Jaunty Jackalope
Mediubuntu is a repository where we can find some applications and codecs that are not installed by default. We can add to the list of repositories from command terminal:

sudo wget http://www.medibuntu.org/sources.list.d/jaunty.list -O /etc/apt/sources.list.d/medibuntu.list

and then

sudo apt-get update && sudo apt-get install medibuntu-keyring && sudo apt-get update

Multimedia Codecs
    sudo apt-get install libdvdread3
    For i386 -- sudo apt-get install w32codecs
    For amd64 -- sudo apt-get install w64codecs
    For ppc -- sudo apt-get install-ppc codecs

Install VLC, Smplayer and Mplayer with all codecs and DVD support
    sudo apt-get install vlc
    sudo apt-get install smplayer
    sudo apt-get install mplayer

Install Flash Player Plugin
    sudo apt-get install flashplugin-nonfree libflashsupport
    sudo apt-get install mozilla-plugin-gnash

Linux MultiMedia Studio - LMMS

LMMS is a free cross-platform alternative to commercial programs like FL Studio®, which allow you to produce music with your computer. This includes the creation of melodies and beats, the synthesis and mixing of sounds, and arranging of samples. You can have fun with your MIDI-keyboard and much more; all in a user-friendly and modern interface.

Features
    * Song-Editor for composing songs
    * A Beat+Bassline-Editor for creating beats and basslines
    * An easy-to-use Piano-Roll for editing patterns and melodies
    * An FX mixer with 64 FX channels and arbitrary number of effects allow unlimited mixing possibilities
    * Many powerful instrument and effect-plugins out of the box
    * Full user-defined track-based automation and computer-controlled automation sources
    * Compatible with many standards such as SoundFont2, VST(i), LADSPA, GUS Patches, and full MIDI support
    * Import of MIDI and FLP (Fruityloops® Project) files

Download:
The following binary-packages are currently available:

    * Windows 2000/XP/Vista - here
    * Ubuntu 8.10 - here
    * openSUSE 11.1 and 11.0 - here

Linux distribution for children

Nowadays kids are getting more and more familiar with computers. That takes place through games, movies, pictures and all kind of educational programs. And now, there is a new solution for you to give your kids the possibility to use a computer in a fun way.

Qimo4Kids.com is a website that was specially developed in order to provide users with all the information they need about a new operative system for kids. This system was created as a version of Linux for kids.

One of the best things about this new solution is the fact that it comes complete with educational games for children aged 3 and up. This is going to be a very good opportunity for your kids to learn and have fun at the same time.

This site is simple as well as agile to navigate through. There is a section with an archive where you will find more information about the latest news as well as the most important past developments.

In case you want to learn more, just take a look at the site and inform yourself about an operating system of its own that your kids are certain to appreciate.

Ubuntu Extra Remix

Ubuntu extras remix is a Linux distribution based on the latest stable release of Ubuntu and contains restricted extras (Flash player, Java, multimedia codecs, additional fonts, unrar) and official updates.

Here are some key features of "Ubuntu extras remix":

· Adobe Flash
· Java
· Ability to play movie DVDs (codecs + CSS decrypter)
· Multimedia codecs (including MP3)
· Additional fonts
· unrar
· Updates: more than 281 updates (for the Linux kernel, Firefox, OpenOffice.org, evolution, f-spot, gedit, nautilus, network-manager, pulseaudio, totem, rythmbox, transmission, brasero, GIMP, etc, etc...)
· Created with reconstructor

Download
* HTTP (direct link): http://superubuntu.linuxfreedom.com/
* Torrent: http://www.mininova.org/tor/2464065/

Installation/Configuration of FUSE FileSystem (sshfs)

Filesystem in Userspace is a simple interface for userspace programs to export a virtual filesystem to the Linux kernel. It also aims to provide a secure method for non privileged users to create and mount their own filesystem implementations.

With FUSE it is possible to implement a fully functional filesystem in a userspace program.

Features include:
    * Simple library API
    * Simple installation (no need to patch or recompile the kernel)
    * Secure implementation
    * Userspace - kernel interface is very efficient
    * Usable by non privileged users
    * Runs on Linux kernels 2.4.X and 2.6.X
    * Has proven very stable over time

Installation: FUSE
1. Download the latest stable FUSE tarball from the SourceForge.net
2. Unpack the archive: tar -zxvf fuse-2.7.4.tar.gz
3. configure FUSE for compilation: ./configure –disable-kernel-module --prefix=/usr
4. Compile FUSE: make
5. If the compilation completes successfully, enter make install to complete the installation of FUSE

Installation sshfs-fuse
1. Download the latest stable sshfs-fuse tarball from SourceForge.net
2. Unpack the archive: tar -zxvf sshfs-fuse-2.2.tar.gz
3. Configure sshfs-fuse for compilation: ./configure --prefix=/usr
4. Compile sshfs-fuse: make
5. If the compilation completes successfully, enter make install to complete the installation of sshfs-fuse

Mount a FUSE Filesystem
Enter sshfs username@server:/directory /mountpoint to use FUSE to mount a directory on a remote server.

Note, that it's recommended to run it as user, not as root. For this to work the mountpoint must be owned by the user. If the username is different on the host you are connecting to, then use the "username@host:" form. If you need to enter a password sshfs will ask for it (actually it just runs ssh which ask for the password if needed). You can also specify a directory after the ":". The default is the home directory.

Installing Google Earth on Ubuntu

1. Download Google Earth from the Google Earth website.
The linux version will be automatically chosen when downloading from Ubuntu.

2. Open a terminal from Applications -> Accessories -> Terminal.
cd into the directory where you saved Google Earth.
For example, if you saved it to the Desktop type: cd ~/Desktop

3.Make it executable by typing:chmod +x GoogleEarthLinux.bin

4.Run the installer by typing:sudo ./GoogleEarthLinux.bin

5. Run Google Earth by selecting Applications -> Internet -> Google Earth.

Removing Internet Junks (ads, banners, pop-ups, etc ..) using privoxy on OpenSuSe

Privoxy is a Web proxy based on Internet Junkbuster with advanced filtering capabilities for protecting privacy, filtering Web page content, managing cookies, controlling access, and removing ads, banners, pop-ups, and other obnoxious Internet junk. Privoxy has a very flexible configuration and can be customized to suit individual needs and tastes. Privoxy is useful for both stand-alone systems and multi-user networks.

Installation: use "1-click" installer to install Privoxy
OpenSuSe 11.1 - here
OpenSuSe 11.0 - here

Having installed privoxy, we need to edit the config file and make some small changes. To edit, run: vi /etc/privoxy/config

You can choose to read the ToC and the Introduction (and of course the descriptions of each option), but if you want to skip that and get to a working proxy, search for the word "listen-address" in the cofig file and set your local ip address and port on which privoxy server will listen.

listen-address 192.168.0.1:8118

(Your ip will most likely be different). This is the IP address of the ethernet port the computer is running on. This can also be loopback (127.0.0.1) if you dont want to share your advert freeing proxy goodness :). The other part (after the ":") is the port number to listen on - this can be almost anything, but unless you need it moved, its probably best to leave it where it is.

Thats our big change here! save and exit the editor your using, then restart the daemon, and your finished: # /etc/init.d/privoxy restart

You should now have a filtering proxy running on the IP and port you just specified. If you want Firefox or some other browser to run through it, you simply change the settings in the browsers configuration.

Firefox:
Open the browser, click Edit -> Preferences. Click the 'connection settings' button, and click on 'manual proxy configuration'. In the top field add the following (as shown in the figure)

You can also go to http://config.privoxy.org/show-status to check the status of you priovoxy server and other configuration details

Creating backup/restore images using dd

Create a hard disk image: dd if=/dev/hda1 of=/home/hda1.bin

Create a compressed disk image: dd if=/dev/hda1 | gzip > /home/hda1.bin.gz

Back up the MBR: dd if=/dev/hda of=/home/hda.boot.mbr bs=512 count=1

Restore MBR (from a Live CD): dd if=/mnt/hda1/home/hda.boot.mbr of=/dev/hda bs=512 count=1

Backup a drive to another drive: dd if=/dev/hda of=/dev/hdb conv=noerror,sync bs=4k

The command:

dd -if /dev/hda1 > partitionimage.dd

will backup "/dev/hda1" partition. A whole drive (including the MBR) could be backed up using just /dev/hda as the input "file". Restoring is done by: dd -if partitionimage.dd -of /dev/hda1

If you have a complete new harddrive and want to restore the backup (or copy your old system to the new drive). First, the new drive has to be bigger or exactly the same size as the old one. First go superuser and switch to runlevel 1 so that you can fumble around with the harddisk without other services interfering

restore either the whole disk to the new drive or one partition (depending on how you made the backup): dd -if partitionimage.dd -of /dev/hda1

If you restored the whole drive (/dev/hda), the system will not automatically create the devices (/dev/hda1, /dev/hda2) if you just restored the whole drive. If you know how to make the devices show up without reboot, write it here, otherwise this is a good moment to reboot.

If you restored the system to a new drive, and your device names changed (for example from /dev/hda to /dev/sda) then you must adapt the bootloader and the mount points. While still on runlevel 1, edit these files:

/boot/grub/menu.list
/etc/fstab

After your system is able to boot and runs again, you can resize your partitions to fill the rest of the new harddisk (if you want that) as described here

QuickStart - IMAP/POP server configuration on OpenSuSe

Dovecot is an IMAP server whose major goals are security and extreme reliability. It uses index files to optimally store the mailbox state, which makes it very fast even with huge mailboxes. Indexes won't prevent external mailbox updates, so Dovecot is still fully compatible with standard Maildir and mbox formats. There's also a fully featured POP3 server included.

Installation: Use "1-click" installer to install dovecot
OpenSuse 11.1 - here
OpenSuse 11.0 - here

Configuration:
To configure dovecot, you edit the file /etc/dovecot/dovecot.conf.

IMAP and POP3. POP3 is useful when e-mail is checked from only one computer, and is best for people who download their email, and then work offline. IMAP is the better choice when you would like to check your mail from multiple computers, at work and home, for example. IMAP has the added benefit of accessing folders on the server, allowing you to organize your e-mail, and access it from anywhere.

IMAPS and POP3S are more secure than the simple IMAP and POP3 because they use TLS encryption to connect.

Once you have chosen, amend the following line in the file /etc/dovecot/dovecot.conf:

protocols = pop3 pop3s imap imaps

This enables those protocols when dovecot is started.

Start dovecot: /etc/init.d/dovecot start

To check that it is running, type the command ps -A|grep dovecot. You should see the dovecot service running. If you have enabled imap, or pop3, you can also try to log in with the commands telnet localhost pop3 or telnet localhost imap. If you see something like the following, the installation has been successful.

poison:# telnet localhost imap
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
* OK Dovecot ready.

This is a very simple configuration of dovecot, check the site to know more about some detail configuration.

How To search for an string in a file using grep

grep searches the input files for lines containing a match to a given pattern list. When it finds a match in a line, it copies the line to standard output (by default), or does whatever other sort of output you have requested with options.

grep can simply be invoked: $ grep 'STRING' filename

This is OK but it does not show the true power of grep. First this only looks at one file. A cool example of using grep with multiple file would be to find all files in a directory that contains the name of a person. This can be easily accomplished using a grep in the following way :

$ grep 'Nikesh J' *

Notice the use of single quotes; This are not essential but in this example it was required since the name contains a space. Double quotes could also have been used in this example.

Grep Regular Expression

grep can search for complicated pattern to find what you need. Here is a list of some of the special characters used to create a regular expression:

`.' The period `.' matches any single character.

`?' The preceding item is optional and will be matched at most once.

`*' The preceding item will be matched zero or more times.

`+' The preceding item will be matched one or more times.

So an example of a regular expression search would be: $ grep "\<[A-Za-z].*" file

This will search for any word which begins with a letter upper or lower case.

For more details check: $ man grep

Perfect Paper Passwords - One Time Password System (OpenSuse)

Almost without exception, today's Internet users prove their identity online using a fixed account name and password. In the past, this simple system provided sufficient security. But with the growing popularity of online banking and eCommerce, the value of stealing online identities has skyrocketed. And the increasing presence and "spyware" and "malware" on innocent users' computers means that users can be "watched" while logging onto their banking and other eCommerce sites. Once their logon credentials have been "captured" and stolen, Internet criminals can easily assume their identity.

The trouble with a username and password is that they never change. We create them, write them down or memorize them, then use them over and over again. What has been needed is an inexpensive system that provides something which changes everytime it is used. GRC's Perfect Paper Passwords system offers a simple, safe and secure, free and well documented solution that is being adopted by a growing number of security-conscious Internet facilities to provide their users with state-of-the-art cryptographic logon security.

For securing SSH into your server, a PPP Pluggable Authentication Module is the best option. An open source PAM has been developed over on Google Code and is what this article uses. These instructions are adapted from the ppp-pam wiki.

Make sure you have the appropriate packages installed.

    * subversion
    * make
    * gcc
    * g++
    * libc6-dev
    * uuid-dev
    * libpam0g-dev
    * openssh-server

Download version 0.2 of the source code and save to your disk. Open a terminal window and extract the source files.

# tar -xvzf ppp-pam-0.2.tar.gz
# cd ppp-pam

Build the code

# cd build
# ../configure
# make

Install the pppauth utility and PAM module in the appropriate folders. (You will need to enter your administrator password to run the following command): # make install

Enable PPP authentication for ssh connections. The specifics here may vary depending on your linux distribution. If you find that they deviate significantly, please post a comment here.

# vi /etc/pam.d/sshd
Enter the following line just below @include common-auth
auth required pam_ppp.so

Close and save the file. Make sure you have the following settings in /etc/ssh/sshd_config:

ChallengeResponseAuthentication yes
UsePAM yes

Switch to the user account you wish to protect and create a PPP sequence key for your user account. This sequence key is the master code used to generate the OTPs: $ pppauth --key

Generate a passcard. Print or save it -- you'll need it to log in over SSH: $ pppauth --text --next 1

Try logging in to test it: $ ssh localhost

$ ssh localhost
Password:
Passcode 1B [1]:
Last login: Sat Apr 18 16:56:43 2009 from localhost
Have a lot of fun..
$

For more commands, run pppauth --help

Installation/Configuration of Last.fm Scrobbler/Player for linux

Last.fm is a UK-based Internet radio and music community website, founded in 2002. It claims over 30 million active users based in more than 200 countries.

Using a music recommender system called "Audioscrobbler", Last.fm builds a detailed profile of each user's musical taste by recording details of all the songs the user listens to, either on the streamed radio stations, the user's computer or some portable music devices. This information is transferred to Last.fm's database ("scrobbled") via a plug in installed into the user's music player. The profile data is then displayed on the user's profile page. The site offers numerous social networking features and can recommend and play artists similar to the user's favorites.

The player allows the user to enter the name of any artist or tag which then gives a choice of a number of similar artist stations, or similar global tag stations. Alternatively, Recommendation radio or any of the user's personal radio stations may be played without the necessity to visit the website.

The player displays the name of the station and track currently playing, the song artist, title and track length as well as album details, the artist's photo and biographical details, album cover art when available, lists of similar artists and the most popular tags and top fans. There are several buttons, allowing the user to love, skip, or ban a song.

Installation:
Download the Scrobbler: here
Untar the source: tar -xvf last.fm-1.4.2.58240.src.tar
Move into the extracted directory: cd last.fm-1.4.2.58240
Fire following command to compile, build & install last.fm:

# ./configure

# make

# make install
After successful installation launch last.fm: last.fm to open up the Scrobbler/Player

Alternative Applications for Windows, Mac and Linux

AlternativeTo is a kind of collaborative directory where you can find alternatives to any application for Windows, Mac and Linux, and if this is not enough you can also find it for online applications. Simply select the operating system which will filter the results for your search, here you can also choose from free or commercial alternatives, and then find the perfect alternative to that application.

TUX with Command Wallpaper

Source gnomelook , wallpaperslife
Combination of these two wallpaper was done by: http://www.linuxzone.es/

Protect your network from worms - PacketFence

If your network is a breeding ground for worms, PacketFence is for you. If you have no idea who connects to your network and who owns a particular computer, PacketFence is for you. If you have no way of mapping a network policy violation to a user, PacketFence is for you

PacketFence is a Free and Open Source network access control (NAC) system. PacketFence is actively maintained and has been deployed in numerous large-scale institutions over the past years. It can be used to effectively secure networks - from small to very large heterogeneous networks.

PacketFence is an open-source network access control (NAC) system which provides an impressive list of supported features. Among them, there are:

Registration
PacketFence supports an optional registration mechanism similar to "captive portal" solutions. An Acceptable Use Policy can be specified such that users cannot enable network access without first accepting it. The duration of a node registration can be a relative value (eg. "four weeks from first network access") or an absolute date (eg. "Thu Jan 20 20:00:00 EST 2009").

Detection of abnormal network activities
Abnormal network activities (computer virus, worms, spyware, etc.) can be detected using local and remote Snort sensors. Beyond simple detection, PacketFence layers its own alerting and suppression mechanism on each alert type. A set of configurable actions for each violation is available to administrators.

Proactive vulnerability scans
Nessus vulnerability scans can be performed on a scheduled or ad-hoc basis. PacketFence correlates the Nessus vulnerability ID's of each scan to the violation configuration, returning content specific web pages about which vulnerability the host may have.

Isolation of problematic devices
PacketFence supports several isolation techniques, including VLAN isolation with VoIP support (even in heterogeneous environments) for multiple switch vendors

Remediation through a captive portal
Once trapped, all HTTP, IMAP and POP sessions are terminated by the PacketFence system. Based on the nodes current status (unregistered, open violation, etc), the user is redirected to the appropriate URL. In the case of a violation, the user will be presented with removal instructions for the particular infection he/she has.
* 802.1X
802.1X is supported through a FreeRADIUS [External] module.

Wireless integration
PacketFence intregrates perfectly with wireless networks through a FreeRADIUS module. This allows you to secure your wired and wireless networks the same way.

DHCP fingerprinting
DHCP fingerprinting can be used to automatically register specific device types (eg. VoIP phones) and to disallow network access to other device types (eg. game consoles).

Installation:
RHEL/CentOS user can use rpm file to install - here

Others can use the tar file - here
untar the source file: tar -zxvf packetfence-1.8.2.tar.gz
Compile the source: ./installer.pl

Safely, easily remove external USB media

Ejecter is a little tool which makes it possible to unmount external devices and eject cd-roms without having to right-click on device icon either on the desktop or in nautilus. It sits in background and shows an icon in the system tray when one or more peripherals are connected to your pc: once clicked it a window appears with the list of the devices (volume name and device type, much clearer than the similar thing available on Windows) and the related eject button.

Installation: Use "1-click" installaer to install the package
OpenSuSe 11.1 - here
OpenSuSe 11.0 - here

Ubuntu user can install Ejecter from getdeb.net
After sucessful installation: Menu: Applications -> Accessories -> Ejecter

How to check/repair (fsck) filesystem after crash or power-outage

At some point your system will crash and you need to perform a manual repair of your file system. A typical situation would be power loss while you are working on the system. You reboot and the system stops and indicates you must perform a manual repair of the system using fsck.

fsck (file system consistency check) is a command used to check filesystem for consistency errors and repair them on Linux filesystems. This tool is important for maintaining data integrity so should be run regularly, especially after an unforeseen reboot (crash, power-outage).

Usage: fsck [-sACVRTNP] [-t fs-optlist] [filesystem] [fs-specific-options]

Filesystem can be either a device's name (e.g. /dev/hda) or its mount point. fsck run with no options will check all devices in /etc/fstab. It might be neccesary to run fsck from single-user mode

Note: You need to be "root" to use any of the below mentioned command

* Take system down to runlevel one: # init 1

* Unmount file system, for example if it is /home (/dev/sda2) file system then type command:

# umount /home OR # umount /dev/sda2

* Now run fsck on the partition: # fsck /dev/sda2

* Specify the file system type using -t option:

# fsck -t ext3 /dev/sda2 OR # fsck.ext3 /dev/sda2

fsck will check the file system and ask which problems should be fixed or corrected. If you don't wanna type y every time then you can use pass -y option to fsck:

# fsck -y /dev/sda2

Please note if any files are recovered then they are placed in /home/lost+found directory by fsck command.

* Once fsck finished, remount the file system: # mount /home

Read man page of fsck for more information.
Make sure you replace /dev/sda2 with your actual device name.

Use fastest mirror for downloads - yum-fastestmirror

Fedora uses a worldwide system of mirror servers to distribute packages. When a Fedora system needs package info, packages, or updates, it will by default request a mirror list from a Fedora server. This list is generated based on the repository and architecture requested as well as the IP address of the requesting system and help locate the geographically closest mirrors. This “geographically closest” mirror is supposed to give you the fastest connection - which unfortunately is usually not the case.

The yum-fastestmirror package provides a Yum plugin which measures the speed of available mirrors and sorts the list so that priority is given to the fastest mirrors; this can result in faster yum operations and reduced network congestion -- and with no additional manual effort beyond installing the plugin.

Installing from the command line: # yum install yum-fastestmirror

One may exclude certain domains from even being listed at all by adding the following line to /etc/yum/pluginconf.d/fastestmirror.conf:
exclude=.tw, .jp

Monitor System Logs With Logwatch - OpenSuSe

Logwatch is a customizable log analysis system. Logwatch parses through your system's logs for a given period of time and creates a report analyzing areas that you specify, in as much detail as you require. Logwatch is easy to use and will work right out of the package on most systems.

Installation: use "1-click" installer to install logwatch
OpenSuse 11.1 - here
OpenSuSe 11.0 - here

Configuration
The default configuration can be found in /usr/share/logwatch/default.conf/logwatch.conf. Take a look around the file, but the main thing you might want to update:

MailTo = root
updates to MailTo = user.name@domain.tld

Now go to console and run command: # logwatch to see the detail output, you can also configure the crontab entry for logwatch to get the daily status mail.

How to enable quota on OpenSuse

Quota allows System Administrator to specify limits on two aspects of disk storage: the number of inodes a user or a group of users may possess; and the number of disk blocks that may be allocated to a user or a group of users.

The idea behind quota is that users are forced to stay under their disk consumption limit, taking away their ability to consume unlimited disk space on a system. Quota is handled on a per user, per file system basis. If there is more than one file system which a user is expected to create files, then quota must be set for each file system separately.

1: To install quota: # yast2 -i quota

2: Edit /etc/fstab and add usrquota,grpquota to the mountpoints of the filesystem to which you want to enable quota (example /disk below)

# vi /etc/fstab
/dev/sda6 /disk ext3 defaults,noatime,usrquota,grpquota 0 0

3) Now go (cd) to the mount point (/disk) and create the quota files

# touch /aquota.user /aquota.group
# chmod 600 /aquota.*

4) Remount the partition: # mount -o remount /disk

5) Run the following command to initialize the quota on the /disk filesystem

# quotacheck -avugm
# quotaon -avug

The -a switch tells quotacheck to perform the check on all filesystems. The -u and -g switches tell it to check for user and group quotas. Using the -m switch means the filesystem will not be remounted as read-only.

The first time you run the quotacheck command, it will throw up several warnings because the filesystem had not been checked before.

quotacheck: Scanning /dev/sda6 [/disk] done
quotacheck: Cannot stat old user quota file: No such file or directory
quotacheck: Cannot stat old group quota file: No such file or directory
quotacheck: Cannot stat old user quota file: No such file or directory
quotacheck: Cannot stat old group quota file: No such file or directory
quotacheck: Checked 20 directories and 661 files
quotacheck: Old file not found.
quotacheck: Old file not found.

6) Your filesystems are now set up to use disk quotas. To turn them on, use the quotaon command:

# quotaon -augv
/dev/sda6 [/disk]: group quotas turned on
/dev/sda6 [/disk]: user quotas turned on

Once quotas are enabled, you can use the edquota command to limit the disk space available to users. The edquota -u username command will open up a text editor wherein you can specify the soft and hard inodes and blocks limits for a particular user. The edquota -g command can similarly be used to edit group quotas.

Encrypt-Decrypt file using OpenSSL

The OpenSSL Project is a collaborative effort to develop a robust, commercial-grade, full-featured, and Open Source toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols as well as a full-strength general purpose cryptography library. The project is managed by a worldwide community of volunteers that use the Internet to communicate, plan, and develop the OpenSSL toolkit and its related documentation.

OpenSSL is based on the excellent SSLeay library developed by Eric A. Young and Tim J. Hudson. The OpenSSL toolkit is licensed under an Apache-style licence, which basically means that you are free to get and use it for commercial and non-commercial purposes subject to some simple license conditions.

To encrypt a file:

$ openssl des3 -salt -in file.log -out file.des3
enter des-ede3-cbc encryption password:
Verifying - enter des-ede3-cbc encryption password:

The above will prompt for a password, or you can put it in with a -k option, assuming you’re on a trusted server.

To Decrypt: openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword

Configure YUM to exclude package upgrades

Yum is an automatic updater and package installer/remover for rpm systems. It automatically computes dependencies and figures out what things should occur to install packages.

And many times its required that when you run the system/package updates you don't want to upgrade certain package and for this just add an exclude line to the end of your [main] section in /etc/yum.conf, and you are done. Your yum.conf should look something like this:

[main]
cachedir=/var/cache/yum
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
installonly_limit=3
exclude=gdm grub

This will prevent upgrades of the gdm and grub. The list of apps in the exclude should be space sepeated. Shell wildcards ( * ? ) can also be included.

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