Wednesday, December 30, 2009

Loads of Linux GAMES

djl is an open-source game manager for Linux, written in Python

download the installer script from
Once you download the file you will need to extract it.
tar -xzvf djl-1.2.20.tar.gz

The contained inside the archive needs to be executable in order to run, so you may have to make it executable by typing the following.
chmod +x

then to run the script, type ./

When you run the script the first time, if you do not have the Python framework installed, you'll get an error. Fortunately The script will point out the missing python-qt4 libraries. Fire up your package manager and install it. Alternatively, use the command line to install the package.
yum install "package name" or apt-get install "package name"

Once you have everything in place, run the application. You will be asked to configure djl. This includes configuring the installation directory for your games, the Web browser of your choice, the default tab in the main menu, the font size, updates, dependencies, and more. Very convenient.

After you download the News items, you're ready to roll.

Go to Repository tab and start enjoying this powerful game manager. You can search the games by genre, or by additional categories, like license or price.

Games are just as easy to un-install as they are to install


Friday, November 6, 2009

Setting up a DHCP server

assuming the Network you want to add a DHCP server to is the network

your router IP Address is

Your ISP's DNS servers IP Address is

the leases that you want to give out are to

first install the DHCP server software.

yum install dhcp.i386

once installed

edit /etc/dhcpd.conf (if it doesn't exist create it)

vi /etc/dhcpd.conf

add in the following lines

ddns-update-style interim;
ignore client-updates;

subnet netmask {


default-lease-time 21600;
max-lease-time 43200;
option routers;
option ip-forwarding off;
option domain-name-servers;
option broadcast-address;
option subnet-mask;

save the file :wq

next, configure the dhcpd service to start at start up

chkconfig dhcpd on

to make sure it is running either reboot or type
/etc/init.d/dhcpd start

that's it , your done. Your DHCP server will give out IP addresses to any clients that connect to your network.
there are many other options that you can add to your DHCP server, like reserving an IP address for a specific mac-address etc

to see all of these option just check out the man pages of dhcpd
man dhcpd

Thursday, November 5, 2009

Source .bashrc when you connect over SSH

If your .bashrc file is not being sourced when you connect to your system over SSH and it only gets sourced when you open up a terminal locally on the system.

you may need to add the following to your etc/profile file

if [ -e ~/.bashrc ]; then
. ~/.bashrc

Tuesday, November 3, 2009

VMWare boot from CD

VMWare can be very frustrating when you try and boot a VM from a CD .

The VM’s BIOS is set to boot from disk first, so you need to change the boot device order. The problem is that the boot process is so fast that you never have enough time to hit the F2 key and enter the bios setup to change the boot order of your VM.
A solution to the problem is to edit the .vmx file in your VM's directory and simply add the following line.

bios.bootDelay = “boot delay in milliseconds”

for example if you want to give yourself 20 seconds add the following line
bios.bootDelay = “20000”

save the file and then restart your Virtual machine.
You will now have enough time to enter into the VM's console and hit the F2 key so that you can edit the boot order in the Bios.

Wednesday, October 28, 2009

Right Click Open Terminal in current folder

nautilus-open-terminal runs on Gnome Windows manager and it allows you to right click in your file manager
and open up your terminal in the current folder. Clearly a very useful tool.

It used to be installed as a default application in many distributions but for some reason it was left out of Fedora 11

To add it back in simply type
sudo yum install nautilus-open-terminal

If it somehow got left out of your Ubuntu installation, then type
sudo apt-get install nautilus-open-terminal

You will need to restart your Gnome session to activate it.

Friday, October 23, 2009

How to Install Google Chrome on Ubuntu

edit the /etc/apt/sources.list file

sudo vim /etc/apt/sources.list

Add one of the following

For ubuntu 9.10 (armic) add the following two lines

deb karmic main
deb-src karmic main

For ubuntu 9.04 (Jaunty) add the following two lines

deb jaunty main
deb-src jaunty main

For ubuntu 8.10 (Intrepid) add the following two lines

deb intrepid main
deb-src intrepid main

Save the file

Next add the GPG key by typing:

sudo apt-key adv --recv-keys --keyserver 0xfbef0d696de1c72ba5a835fe5a9bf3bb4e5e17b5

Update the source list. by typing

sudo apt-get update

Install chromium by typing

sudo apt-get install chromium-browser


Monday, October 19, 2009

Clone a hard Drive

Good, easy way to clone a hard drive.

dd which is used for converting and copying files, can be used as a powerful and simple image cloning application.

dd if=/dev/hda of=/dev/hdb


if you want to see your progress

then type in another terminal
kill -SIGUSR1 xxxx
were xxxx is the process ID of the running dd process

and the progress will report on the original terminal that you started your cloning operation on.

Wednesday, October 14, 2009

share a single mouse and keyboard accross multiple computers

Here's the scenario.

you have 3 PC's on your Desk. One running Linux , One running MAC OS and the other running Windows XP.

all 3 with their own Monitor .

wouldn't it be cool, to be able to use the same Mouse and keyboard for all 3 PC's. and to be able to copy and paste, Text, Images and HTML content between the PC's.

No Problem, (drum roll...) ... in steps Synergy.

Synergy lets you share a single mouse and keyboard between multiple computers with different operating systems, each with its own display.

Redirecting the mouse and keyboard is as simple as moving the mouse off the edge of your screen. Synergy also merges the clipboards of all the systems into one, allowing you to cut-and-paste between systems. it also synchronizes screen savers so they all start and stop together.

Synergy uses TCPIP to communicate mouse position and keyboard keystrokes between the PC's. So all you need for Synergy to work is to have your PC's connected to the same network. (No additional hard ware is required)

you can download synergy from

and read the user guide and installation instructions from

Tuesday, October 6, 2009

Shutdown a Windows Machine from your Linux Machine

Ever need to reboot or shutdown a Windows machine on your network, from your Linux workstation.
No problem.

apt-get install samba-common package
yum install samba-common package

net rpc shutdown -I ipAddressOfWindowsPC -U username%password

This will issue a shutdown command to the Windows machine. username must be an administrator on the Windows machine.

Other commands are:

net rpc shutdown -r : reboot the Windows machine

net rpc abortshutdown : abort shutdown of the Windows machine


net rpc

to show all commands

Monday, September 28, 2009

How to get a complete list of packages that are installed on your system

dpkg --get-selections

will show you a complete list of packages installed on your Ubuntu system

rpm -qa
will give you the complete list on a Fedora / Redhat /CentOS system

since these lists are long its a good idea to pipe them to less

dpkg --get-selections | less

rpm -qa | less

Friday, September 25, 2009

Argument list too long

Today I was limited by rm

I needed to clean up a folder by deleting previous years (2008) log files which amounted to a few thousand files

rm logs-2008*

returned me the error
/bin/rm:Argument too long

The reason for this error is a limitation of your running kernel and will limit you to other commands as well. Like mv and cp, if the amount of files you want to act on is larger than the set limitation.

a work around is to pipe the matching files to rm one at a time.
To do this, issue the following command

find -name 'log2008*' | xargs rm (substitute 'log2008*' for your search string)

If the files you are trying to remove have spaces in them, then you need to use the following command

find -name 'log2008*' | -print0 | xargs -0 rm

Thursday, September 24, 2009

Static Routes

To add a static route to say the network from your machine through your gateway router who's IP is

route add -net netmask gw dev eth0

will add the route to your kernel and it will be available immediately. However this will not survive a reboot.
To make this persistent after a reboot you need to input the route into a configuration file

on Ubuntu edit


and Red hat / Centos / Fedora

edit /etc/sysconfig/network-scripts/route-eth0

if the route-eth0 file file does not exist (it probably won't) then create it
and add the following via

save the file and then restart networking to read in the new route
/etc/init.d/networking restart

Wednesday, July 8, 2009

How to install Google Chrome on Fedora

vi /etc/yum.repos.d/chromium.repo

paste the following into the file

name=Chromium Test Packages

:wq to save

then yum install chromium


Friday, May 15, 2009

Dreambox HD

Every once in a while something comes along that really impresses me, my Blackberry was one of them, Virtual Machines another, my WD 1 Terabyte Mybook and now dream box HD has just been added to that list.
The dream box is a Linux based set-top box with a MIPS processor, a Satellite card , gigabit Ethernet card, USB slot digital audio out and DVI / HDMI out .(dependiing on the model you buy)
connected to a motorized satellite dish, you can receive thousands of Satellite channels available under the Sky, as you can imagine , there is no shortage of choice of channels,
The HD channels I must say are awesome to watch, and by installing an internal 500GB Sata drive, you can pause live television, and record 77 hours of HD television in HD.
Were the Dream box comes into its own, is the pluggins that are available for it, and the fact that it is a Linux O.S connected to your home network and the Internet, means that it easily serves as a HD media center for all of your Multimedia content. and the possibilities are endless. My current setup allows me to stream television to every PC or Laptop in my house, I can change channels from the web interface available to every PC laptop in my house, my dream box also accesses my WD 1 terabyte Mybook drive were all my HD home video is stored, as well as all my digital pictures, which I can now enjoy in the comfort of my lounge in full HD and in 5.1 surround sound. My MP3 collection is now served up to my HiFi set and my Media tomb UPnP stream is also accessible via the Dreambox. I can access my dreambox from a blackberry, veiw the program guide and setup a recording from a Blackberry or any 3G phone.
the dream box has been the missing link that I've been waiting for that has made complete media convergence for the home in HD now easy to achieve.
the dreambox 8000 HD can take up to 4 tuners , which means you can record 3 different channels at the same time whilst watching a 4th, provided they are all on the same Satellite.
Now to find the time to do anything Else.

Wednesday, April 1, 2009

using NMAP to Scan your entire network for Conficker

Since a signature has been discovered that conficker worm leaves
on infected machines, you can now scan a machine and ask it ,if it is infected with the conficker worm,
beta5 version of NMAP provides this ability.

follow these quick steps to scan entire networks and give them a clean
bill of health from the conficker worm.
to download and install Nmap beta 5 do the following:

bzip2 -cd nmap-4.85BETA5.tar.bz2 | tar xvf -
cd nmap-4.85BETA5


su root
make install

to Scan for conficker type the following

nmap -PN T4 -p139,445 -n -v --script=smb-check-vulns --script-args safe=1 [target network]

nmap -PN T4 -p139,445 -n -v --script=smb-check-vulns --script-args safe=1

the scan will take a while depending on the size of your network.

Tuesday, March 31, 2009

saving a file in VI as root

It often happens that you open up a file for editing using vi or vim and only when you come to save the file, you realise you did not open the file with root privileges and are unable to save the file.

when you type :wq!
you get E212: Can't open file for writing.

If that happens to you , simply type

:w !sudo tee %

you will be asked for your sudo password
enter your password and
press enter when asked

(vi/vim will detect that the file has been changed and ask whether you want
it to be reloaded.)

As a shortcut, you can define your own command.

Put the following in your /etc/vimrc

command W w !sudo tee % > /dev/null

and then in future simply type


Friday, March 27, 2009

How to Stop yum from updating your Kernel

On a Server and also on your own machine, kernel Upgrades can break already installed 3rd party Applications, since the application would have been compiled for use on a specific kernel, I find this to be particularly a problem with vmware and Virtual box, every time my system upgrades its kernel there are a few packages that i need to recompile to get to work, this is a real pain, and on your server can lead to serious problems. To stop yum from updating your Kernel
You can tell yum to skip kernel updates by adding kernel-* to the 'exclude=' option in /etc/yum.conf. if the exclude option does not exist simply add it, add in a line that says exclude=kernel-*
you can do the same for any package that you do not want to update, for example, I run a patched version of postfix on one of my servers, since ive included a quota patch when I compiled it , I do not want postfix to upgrade to an unpatched version. So to stop that particular server from upgrading postfix I simply added postfix to the 'exclude=' option in /etc/yum.conf
you can add multiple exclude options by simply adding exclude=app_name_to_exclude under one another.

Tuesday, March 24, 2009

White Background

Test smtp server with required authentication

To test your smtp server, to see if it is an open relay or to
test if your authentication works on it. Use telnet to connect
to the server, this allows you to very quickly test different connection
scenarios to the server. this method is very useful if you
want to test how your smtp server behaves from different remote locations,
and all you have is an ssh account into the locations you want to test from.
You can simply ssh into the remote location you want to test from and then
follow these steps
In this example I wanted to test if basic outgoing smtp authentication was working on my server (everything in Bold is what you type everything not in bold is the servers response)

telnet 25

Connected to
Escape character is '^]'.
220 ESMTP ready
ehlo ESMTP hello
250-SIZE 10485760
250 OK
auth login
334 VXNlcm5hbWU6
334 UGFzc3dvcmQ6
235 Authentication successful
250 Sender accepted
250 Recipient accepted
354 Ready to receive data; remember .
subject: any subject

double space (ie hit the space bar twice)

then enter any text for the body of the email


250 Mail queued for delivery
quit ESMTP is closing connection
221 Good bye

the Y2xpdmUuZ2VyYWRhQHJzMi5jb20=
and cnMy

is my username and password encoded in Basd64 cypher

you have to encode it in base64 for the server to understand it.
you can use the following online tool to encode and decode to and from base64

perl -MMIME::Base64 -e 'print encode_base64("username");'
perl -MMIME::Base64 -e 'print encode_base64("password");'

will encode base64 for you or alternatively you can use an online encoder like

How to Encrypt/decrypt files

If you want to protect files so that they can transverse across cyberspace safely, or you just want to protect them from
prying eyes with a password.

use the gpg command.

gpg -c filename

You will be asked for a pass phrase.

enter your pass phrase.

You will be asked to repeat your pass phrase
a file will be created with the .gpg extention

Caution: if you forget your pass phrase you will not be able to recover your file. the encryption used is that good.

to decrypt the file simply type
gpg filename.gpg

enter your pass phrase when asked.

To do multiple files I usually zip them into one zip file and then encrypt the zip file.
you can do this in one shot by typing the following
zip - file1 file2 file3 file4 file5 | gpg -eat >

Friday, March 20, 2009

Alternating between directories in your Terminal

often, I am working in a directory which has a long path eg /home/cgerada/long/complicated/directory/structure/folder/

and then want to temporally change to another directory to do something and change back to the directory I was in

instead of using cd to change to the other directory rather use
pushd eg pushd /directory

that way when you are done in /directory and you want to return to /home/cgerada/long/complicated/directory/structure/folder/

simply type popd

and you will be returned to /home/cgerada/long/complicated/directory/structure/folder/

cd - is also very useful and will take you to your last working directory

and is great for switching between 2 directories .. just type cd - and then cd- again to alternate between 2 working directories

Thursday, March 19, 2009

Quick way to Rip a DVD

Insert your DVD into your DVD Drive of your PC/Laptop

and type the following in your terminal

dd if=/dev/cdrom of=/cdrom_image.iso
your DVD will be saved as an iso image in your current directory.

It doesn't even need to be that complicated.
These commands will work too (isn't Linux wonderful?)
cp /dev/cdrom cd.iso
cat /dev/cdrom > cd.iso

Saturday, March 14, 2009


ssh reads configuration information from a config file
(if you have one) before connecting to a machine.

This way you can tell ssh how you want to connect toparticular machines. If you have a lot of different
machines that you connect to,  especially if youconnect to them on different ports and with different
user names then
it is a great idea to create the following file

type vi .ssh/config

and popultate the config file with the information
of the machines that you connect to.
Host *
Port 2222
User clive
Host ipcop1
Port 222
User root
Host home
User clive
Port 768

with the above information in the config file if you typessh
will be the equivalent of typing
ssh -p 2222

and typing scp file1 ipcop1:file1
will be the equavelent of typing 
scp -P222 file1 root@ipcop1

as you can see the config file can save you a lot of time.

The port and the username from the config file will
automatically be used every time you connect to the
machines listed in the config file.
Were this is especially usefull is when you want to
copy ssh keys to a remote machine using the
ssh-copy id command when the remote machine uses
a different port to 22.

Lets say you want to copy your public keys to your
machine called home but machine home only allows
 ssh connection on port 768. By adding in the information
above for machine home. I can now simply type
ssh-copy-id -i ~/.ssh/ home
to transfer the keys.

if you get the following error when using ssh
Bad owner or permissions on .ssh/config
then you must change the permissions of the config file.
cd .ssh
chmod 600 config

Sunday, March 8, 2009


To Play a commercial DVD in your media player
you need to install libdvdcss

you will also need libdvdcss to be able to backup your commercial DVD's ;)

yum install libdvdcss

or apt-get install libdvdcss depending on your distro

Monday, February 23, 2009

RPM Fusion Repository

RPM Fusion Repository provides software that the Fedora Project
Red Hat doesn't want to ship.
You will find software like VLC media player, Mencoder FFmpeg
and other
software that is not available in the stock Fedora or
Red hat repositories

to install the RPM Fusion repository on your system simply type
the following

rpm -ivh

then you can install software directly ie
yum install vlc

How to find out what Distro you are running

uname -a will give you information about your running Kernel. To find out what Distribution is installed on a Particular system try one the following:

cat /etc/issue


cat /proc/version


cat /etc/*release