recovering from a read only / mount

When the boot process aborts upon failing to find a removed or failed hard disk due to the system not finding the device that your /etc/fstab file references , it asks for a password and gives you the option to drop into maintenance mode , however when in maintenance mode you are unable to edit your /etc/fstab file to fix the problem since your / partition is mounted Read only!

to fix the situation simply type

mount -n -o remount /
will remount the / partition in rw mode and you can now edit /etc/fstab and remove the
line with the faulty disk or wrong entry, and then reboot as normal.

Encrypt a file whilst in Vim

Encrypt File in Vim
Save and encrypt the current file:
:X
Enter encryption key: ********
Enter same key again: ********
Once you’ve encrypted a file using :X, the next time you open that file, Vim
will prompt for the encryption key.

How to Upgrade from Fedora 12 to Fedora 13 (32 bit and 64 bit versions)

Do the following as root.

download latest fedora repos

For 32 bit version type:

wget ftp://download.fedora.redhat.com/pub/fedora/linux/releases/13/Everything/i386/os/Packages/fedora-release-13-1.noarch.rpm

or for 64 bit version type:

wget ftp://download.fedora.redhat.com/pub/fedora/linux/releases/13/Everything/x86_64/os/Packages/fedora-release-13-1.noarch.rpm

import gpg-key

rpm --import ftp://download.fedora.redhat.com/pub/fedora/linux/releases/13/Everything/i386/os/RPM-GPG-KEY-fedora-i386

or for 64 bit version type:

rpm --import ftp://download.fedora.redhat.com/pub/fedora/linux/releases/13/Everything/x86_64/os/RPM-GPG-KEY-fedora-i386

rpm --import ftp://download.fedora.redhat.com/pub/fedora/linux/releases/13/Everything/i386/os/RPM-GPG-KEY-fedora-i386 

install rpmlibs dependency. Required to install fedora-release-13

yum install rpm-libs -y

upgrade fedora release

rpm -Uvh fedora-release-13-1.noarch.rpm

upgrade fedora distro

yum upgrade -y

Reboot and Enjoy

Compose Key

I often need to type characters that aren’t on the keyboard, like € ½ ÷ © ¥ or ¢.

compose key to the rescue.

pick a key on your keyboard you don’t use much, like [Insert], [CapsLock], or [menu], and make it the “compose key”.

Then to make any character, you just hit the compose key, then type the two obvious keys that, when combined, make up the character.

For example:

* To get €, just type e then =

* To get ©, just type o then c

* To get ® just type o then r

* To get £, just type L then -

* To get ¥, just type Y then =

* ¢ is c then |

* ÷ is - then :

* ½ is 1 then 2

* ¼ is 1 then 4

* ñ is n then ~

By default this function is not assigned to any key. You can tell the X server what key to use for this function with the following command
setxkbmap -option compose:keyname

for example

setxkbmap -option compose:caps

to assign it to the caps-lock key.

or setxkbmap -option compose:rwin

to assign your right "Windows" key
to make it persisistent after a reboot simply insert the command in your
/etc/rc.local file

Loads of Linux GAMES

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

download the installer script from http://en.djl-linux.org/?q=node/19
Once you download the file you will need to extract it.
tar -xzvf djl-1.2.20.tar.gz

The djl.sh 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 djl.sh

then to run the script, type ./djl.sh

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

Enjoy

Setting up a DHCP server

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

192.168.1.0/24 network

your router IP Address is 192.168.1.1

Your ISP's DNS servers IP Address is 194.158.2.2

the leases that you want to give out are 192.168.1.128 to 192.168.1.254

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 192.168.1.0 netmask 255.255.255.0 {

range 192.168.1.128 192.168.1.254;

default-lease-time 21600;
max-lease-time 43200;
option routers 192.168.1.1;
option ip-forwarding off;
option domain-name-servers 194.158.2.2;
option broadcast-address 192.168.1.255;
option subnet-mask 255.255.255.0;

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
type
man dhcpd

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
fi

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.

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.

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 http://ppa.launchpad.net/chromium-daily/ppa/ubuntu karmic main
deb-src http://ppa.launchpad.net/chromium-daily/ppa/ubuntu karmic main

For ubuntu 9.04 (Jaunty) add the following two lines

deb http://ppa.launchpad.net/chromium-daily/ppa/ubuntu jaunty main
deb-src http://ppa.launchpad.net/chromium-daily/ppa/ubuntu jaunty main

For ubuntu 8.10 (Intrepid) add the following two lines

deb http://ppa.launchpad.net/chromium-daily/ppa/ubuntu intrepid main
deb-src http://ppa.launchpad.net/chromium-daily/ppa/ubuntu intrepid main

Save the file

Next add the GPG key by typing:

sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 0xfbef0d696de1c72ba5a835fe5a9bf3bb4e5e17b5

Update the source list. by typing

sudo apt-get update

Install chromium by typing

sudo apt-get install chromium-browser

Done

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

done

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.

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 http://synergy2.sourceforge.net/

and read the user guide and installation instructions from http://synergy2.sourceforge.net/running.html

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
or
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

Type:

net rpc

to show all commands

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

and
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

and
rpm -qa | less

Get Counted (The Linux Counter)

http://counter.li.org/

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

Static Routes

To add a static route to say the 10.10.1.0/24 network from your machine through your gateway router who's IP is 192.168.1.1


route add -net 10.10.1.0 netmask 255.255.255.0 gw 192.168.1.1 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

/etc/network/interfaces

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

10.10.1.0/24 via 192.168.1.1

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

How to install Google Chrome on Fedora

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

paste the following into the file

[chromium]
name=Chromium Test Packages
baseurl=http://spot.fedorapeople.org/chromium/F$releasever/
enabled=1 
gpgcheck=0


:wq to save

then yum install chromium

voila

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.

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:

wget http://download.insecure.org/nmap-dist/nmap-4.85BETA5.tar.bz2
bzip2 -cd nmap-4.85BETA5.tar.bz2 | tar xvf -
cd nmap-4.85BETA5
./configure
make
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]

eg:
nmap -PN T4 -p139,445 -n -v --script=smb-check-vulns --script-args safe=1 192.168.1.0/24

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