Howto Red hat enterprise Linux 5 configure the network card

Red hat Linux provides following tools to make changes to Network configuration such as add new card, assign IP address, change DNS server etc.[a] GUI tool (X Windows required) - system-config-network
[b] Command line text based GUI tool (No X Windows required) - system-config-network
[c] Edit configuration files stored in /etc/sysconfig/network-scripts/ directory.

Following instructions are compatible with
(1) Cent OS Linux
(2) Fedora Core Linux
(3) Red Hat Enterprise Linux (RHEL) 3/4/5

Note: If you are using Debian or Ubuntu Linux, please see this configuration howto.
Method # 1: GUI tool system-config-network

Type the following command at shell prompt (open x terminal):
$ system-config-network &

Method : Edit configuration files stored in /etc/sysconfig/network-scripts/

You can configure network card by editing text files stored in /etc/sysconfig/network-scripts/ directory. First change directory to /etc/sysconfig/network-scripts/:
# cd /etc/sysconfig/network-scripts/

You need to edit / create files as follows:
/etc/sysconfig/network-scripts/ifcfg-eth0 : First Ethernet card configuration file

To edit/create first NIC file, type command:
# vi ifcfg-eth0

Append/modify as follows:

DEVICE=eth0
BOOTPROTO=static
DHCPCLASS=
HWADDR=00:30:48:56:A6:2E
IPADDR=10.10.29.66
NETMASK=255.255.255.192
ONBOOT=yes

Save and close the file. Define default gateway (router IP) and hostname in /etc/sysconfig//network file:
# vi /etc/sysconfig/network

Append/modify configuration as follows:
NETWORKING=yes
 HOSTNAME=www.cheenu.com
GATEWAY=10.10.29.65

Save and close the file. Restart networking:
# /etc/init.d/network restart

Make sure you have correct DNS server defined in /etc/resolv.conf file:
# vi /etc/resolv.conf

Setup DNS Server as follows:
nameserver 10.0.80.11
nameserver 10.0.80.12

Save and close the file. Now you can ping the gateway/other hosts:
$ ping 10.0.80.12

Output:
PING 10.0.80.12 (10.0.80.12) 56(84) bytes of data.
64 bytes from 10.0.80.12: icmp_seq=1 ttl=251 time=0.972 ms
64 bytes from 10.0.80.12: icmp_seq=2 ttl=251 time=1.11 ms

***************all the best**********************

How Do I Enable Remote Access To MySQL Database Server?

By default remote access to MySQL database server is disabled for security reasons. However, some time you need to provide remote access to database server from home or a web server.
MySQL Remote Access
You need type the following commands which will allow remote connections.
Step # 1: Login Using SSH (if server is outside your data center)
First, login over ssh to remote MySQL database server:
ssh user@mysql.nixcraft.i
Step # 2: Edit my.cnf File
Once connected you need to edit the MySQL server configuration file my.cnf using a text editor such as vi.
If you are using Debian Linux file is located at /etc/mysql/my.cnf location
If you are using Red Hat Linux/Fedora/Centos Linux file is located at /etc/my.cnf location
If you are using FreeBSD you need to create a file /var/db/mysql/my.cnf
Edit /etc/my.cnf, run:
# vi /etc/my.cnf
Step # 3: Once file opened, locate line that read as follows
[mysqld]
Make sure line skip-networking is commented (or remove line) and add following line
bind-address=YOUR-SERVER-IP
For example, if your MySQL server IP is 65.55.55.2 then entire block should be look like as follows:
[mysqld]
user = mysql
pid-file = /var/run/mysqld/mysqld.pid
socket = /var/run/mysqld/mysqld.sock
port = 3306
basedir = /usr
datadir = /var/lib/mysql
tmpdir = /tmp
language = /usr/share/mysql/English
bind-address = 65.55.55.2
# skip-networking
....
..
....
Where,
bind-address : IP address to bind to.
skip-networking : Don’t listen for TCP/IP connections at all. All interaction with mysqld must be made via Unix sockets. This option is highly recommended for systems where only local requests are allowed. Since you need to allow remote connection this line should be removed from my.cnf or put it in comment state.
Step# 4 Save and Close the file
Restart the mysql server, enter:
# /etc/init.d/mysql restart
Step # 5 Grant access to remote IP address
Connect to mysql server:
$ mysql -u root -p mysql
Grant access to a new database
If you want to add a new database called foo for user bar and remote IP 202.54.10.20 then you need to type the following commands at mysql> prompt:
mysql> CREATE DATABASE foo;
mysql> GRANT ALL ON foo.* TO bar@'202.54.10.20' IDENTIFIED BY 'PASSWORD';
How Do I Grant Access To An Existing Database?
Let us assume that you are always making connection from remote IP called 202.54.10.20 for database called webdb for user webadmin, To grant access to this IP address type the following command At mysql> prompt for existing database, enter:
mysql> update db set Host='202.54.10.20' where Db='webdb';
mysql> update user set Host='202.54.10.20' where user='webadmin';
Step # 5: Logout of MySQL
Type exit command to logout mysql:
mysql> exit
Step # 6: Open port 3306
You need to open TCP port 3306 using iptables or BSD pf firewall.
A sample iptables rule to open Linux iptables firewall
/sbin/iptables -A INPUT -i eth0 -p tcp --destination-port 3306 -j ACCEPT
OR only allow remote connection from your web server located at 10.5.1.3:
/sbin/iptables -A INPUT -i eth0 -s 10.5.1.3 -p tcp --destination-port 3306 -j ACCEPT
OR only allow remote connection from your lan subnet 192.168.1.0/24:
/sbin/iptables -A INPUT -i eth0 -s 192.168.1.0/24 -p tcp --destination-port 3306 -j ACCEPT
Finally save all rules:
# service iptables save
A sample FreeBSD / OpenBSD pf rule ( /etc/pf.conf)
pass in on $ext_if proto tcp from any to any port 3306
OR allow only access from your web server located at 10.5.1.3:
pass in on $ext_if proto tcp from 10.5.1.3 to any port 3306 flags S/SA synproxy state
Step # 7: Test it
From your remote system or your desktop type the following command:
$ mysql -u webadmin –h 65.55.55.2 –p

Where,
-u webadmin: webadmin is MySQL username
-h IP or hostname: 65.55.55.2 is MySQL server IP address or hostname (FQDN)
-p : Prompt for password
You can also use telnet to connect to port 3306 for testing purpose:
$ telnet 65.55.55.2 3306

Linux routing basics

Creating routes in Linux : Basic Linux routing 
Add a route to a network:

#route add -net network/mask gw default-gateway

Example

#route add -net 10.10.10.0/24 gw 192.168.0.1

Adding default gateway
#route add default gw default-gateway

Example

#route add default gw 192.168.0.1

Adding a route to specific host
#route add -host host-name gw default-gateway

Example:

#rotue add -host 2.34.5.6 gw 192.168.0.1

Deleting route to a network
#route del -network network/subnet default-gateway

Example

#route del -net 10.10.10.0/24 gw 192.168.0.1

Deleting default gateway

#route del default gw default-gatway
Example :
#route del default gw 192.168.0.1
Deleting specific host from routing table

#route del -host ip-add gw default-gateway

Example

#route del -host 10.10.10.45 gw 192.168.0.1

Seeing routing table

#netstat -rn
#route

Note : The old gate way will still remain and may need to be taken out for the system to function properly. Routes are made permanent in Red Hat Linux by adding routes to/etc/sysconfig/static-routes. 

Linux File Systems: Ext2 vs Ext3 vs Ext4

ext2, ext3 and ext4 are all filesystems created for Linux. This article explains the following:
High level difference between these filesystems.
How to create these filesystems.
How to convert from one filesystem type to another.

 Ext2

Ext2 stands for second extended file system.
It was introduced in 1993. Developed by Rémy Card.
This was developed to overcome the limitation of the original ext file system.
Ext2 does not have journaling feature.
On flash drives, usb drives, ext2 is recommended, as it doesn’t need to do the over head of journaling.
Maximum individual file size can be from 16 GB to 2 TB
Overall ext2 file system size can be from 2 TB to 32 TB

Ext3
Ext3 stands for third extended file system.
It was introduced in 2001. Developed by Stephen Tweedie.
Starting from Linux Kernel 2.4.15 ext3 was available.
The main benefit of ext3 is that it allows journaling.
Journaling has a dedicated area in the file system, where all the changes are tracked. When the system crashes, the possibility of file system corruption is less because of journaling.
Maximum individual file size can be from 16 GB to 2 TB
Overall ext3 file system size can be from 2 TB to 32 TB
There are three types of journaling available in ext3 file system.
Journal – Metadata and content are saved in the journal.
Ordered – Only metadata is saved in the journal. Metadata are journaled only after writing the content to disk. This is the default.
Writeback – Only metadata is saved in the journal. Metadata might be journaled either before or after the content is written to the disk.
You can convert a ext2 file system to ext3 file system directly (without backup/restore).
Ext4
 
Ext4 stands for fourth extended file system.
It was introduced in 2008.
Starting from Linux Kernel 2.6.19 ext4 was available.
Supports huge individual file size and overall file system size.
Maximum individual file size can be from 16 GB to 16 TB
Overall maximum ext3 file system size is 1 EB (exabyte). 1 EB = 1024 PB (petabyte). 1 PB = 1024 TB (terabyte).
Directory can contain a maximum of 64,000 subdirectories (as opposed to 32,000 in ext3)
You can also mount an existing ext3 fs as ext4 fs (without having to upgrade it).
Several other new features are introduced in ext4: multiblock allocation, delayed allocation, journal checksum. fast fsck, etc. All you need to know is that these new features have improved the performance and reliability of the filesystem when compared to ext3.
In ext4, you also have the option of turning the journaling feature “off”.
Warning: Don’t execute any of the commands given below, if you don’t know what you are doing. You will lose your data!

Creating an ext2, or ext3, or ext4 filesystem
 
Once you’ve partitioned your hard disk using fdisk command, use mke2fs to create either ext2, ext3, or ext4 file system.
Create an ext2 file system:
mke2fs /dev/sda1
Create an ext3 file system:
mkfs.ext3 /dev/sda1

(or)

mke2fs –j /dev/sda1
Create an ext4 file system:
mkfs.ext4 /dev/sda1

(or)

mke2fs -t ext4 /dev/sda1
Converting ext2 to ext3
For example, if you are upgrading /dev/sda2 that is mounted as /home, from ext2 to ext3, do the following.
umount /dev/sda2

tune2fs -j /dev/sda2

mount /dev/sda2 /home
Note: You really don’t need to umount and mount it, as ext2 to ext3 conversion can happen on a live file system. But, I feel better doing the conversion offline.
Converting ext3 to ext4
If you are upgrading /dev/sda2 that is mounted as /home, from ext3 to ext4, do the following.
umount /dev/sda2

tune2fs -O extents,uninit_bg,dir_index /dev/sda2

e2fsck -pf /dev/sda2

mount /dev/sda2 /home
Again, try all of the above commands only on a test system, where you can afford to lose all your data.

Perform SSH and SCP Without Entering Password on openSSH

In this article, I’ll explain how to perform ssh and scp without entering the password using the SSH Public Key authentication with SSH Agent on openSSH
There are two levels of security in the SSH key based authentication. In order for you to login, you need both the private key and the passphrase. Even if one of them is compromised, attacker still cannot login to your account, as both of them are needed to login. This is far better than typical password based authentication, where if the password is compromised, attacker can gain access to the system.
There are two ways to perform ssh and scp without entering the password:
No passphrase. While creating key pair, leave the passphrase empty. Use this option for the automated batch processing. for e.g. if you are running a cron job to copy files between machines this is suitable option.
Use passphrase and SSH Agent. If you are using ssh and scp interactively from the command-line and you don’t want to use the password everytime you perform ssh or scp, I don’t recommend the previous option (no passphrase), as you’ve eliminated one level of security in the ssh key based authentication. Instead, use the passphrase while creating the key pair and use SSH Agent to perform ssh and scp without having to enter the password everytime as explained in the steps below.
Following 8 steps explains how to perform SSH and SCP from local-host to a remote-host without entering the password on openSSH system

1. Verify that local-host and remote-host is running openSSH

 [local-host]$ ssh -V
OpenSSH_4.3p2, OpenSSL 0.9.8b 04 May 2006

[remote-host]$ ssh -V
OpenSSH_4.3p2, OpenSSL 0.9.8b 04 May 2006

2. Generate key-pair on the local-host using ssh-keygen

[local-host]$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/jsmith/.ssh/id_rsa):<Hit enter>
Enter passphrase (empty for no passphrase): <Enter your passphrase here>
Enter same passphrase again:<Enter your passphrase again>
Your identification has been saved in /home/jsmith/.ssh/id_rsa.
Your public key has been saved in /home/jsmith/.ssh/id_rsa.pub.
The key fingerprint is:
31:3a:5d:dc:bc:81:81:71:be:31:2b:11:b8:e8:39:a0 jsmith@local-host

 The public key and private key are typically stored in .ssh folder under your home directory. In this example, it is under /home/jsmith/.sshd. You should not share the private key with anybody.
By default the ssh-keygen on openSSH generates RSA key pair. You can also generate DSA key pair using: ssh-keygen -t dsa command.

3. Install public key on the remote-host

Copy the content of the public key from the local-host and paste it to the /home/jsmith/.ssh/authorized_keys on the remote-host. If the /home/jsmith/.ssh/authorized_keys already has some other public key, you can append this to the end of it. If the .ssh directory under your home directory on remote-host doesn’t exist, please create it.

[remote-host]$ vi ~/.ssh/authorized_keys
ssh-rsa ABIwAAAQEAzRPh9rWfjZ1+7Q369zsBEa7wS1RxzWR jsmith@local-host

In simple words, copy the local-host:/home/jsmith/.ssh/id_rsa.pub to remote-host:/home/jsmith/.ssh/authorized_keys

4. Give appropriate permission to the .ssh directory on the remote-
 host.
 [remote-host]$ chmod 755 ~/.ssh
[remote-host]$ chmod 644 ~/.ssh/authorized_keys

 5. Login from the local-host to remote-host using the SSH key authentication to verify whether it works properly.

[local-host]$ <You are on local-host here>

[local-host]$ ssh -l jsmith remote-host
Enter passphrase for key '/home/jsmith/.ssh/id_rsa': <Enter your passphrase here>
Last login: Sat Jun 07 2008 23:03:04 -0700 from 192.168.1.102
No mail.

[remote-host]$ <You are on remote-host here>

6. Start the SSH Agent on local-host to perform ssh and scp without having to enter the passphrase several times

Verify whether SSH agent is already running, if not start it as shown below.
[local-host]$ ps -ef | grep ssh-agent
511 9789 9425 0 00:05 pts/1 00:00:00 grep ssh-agent

[local-host]$ ssh-agent $SHELL

[local-host]$ ps -ef | grep ssh-agent
511 9791 9790 0 00:05 ? 00:00:00 ssh-agent /bin/bash
511 9793 9790 0 00:05 pts/1 00:00:00 grep ssh-agent

7. Load the private key to the SSH agent on the local-host

[local-host]$ ssh-addEnter passphrase for /home/jsmith/.ssh/id_rsa: <Enter your passphrase here>
Identity added: /home/jsmith/.ssh/id_rsa (/home/jsmith/.ssh/id_rsa)
Following are the different options available in the ssh-add:
ssh-add <key-file-name>: Load a specific key file.
ssh-add -l: List all the key loaded in the ssh agent.
ssh-add -d <key-file-name>: Delete a specificy key from the ssh agent
ssh-add -D: Delete all key

8. Perform SSH or SCP to remote-home from local-host without entering the password

local-host]$<You are on local-host here>
[local-host]$ ssh -l jsmith remote-host
Last login: Sat Jun 07 2008 23:03:04 -0700 from 192.168.1.102
No mail.
<ssh did not ask for passphrase this time>
[remote-host]$ <You are on remote-host here>

Linux disk recovery

After any power problem with the linux machine, the filesystem could be corrupted and you may not be able to login. When this happens, you will need e2fsck, the tool to recover ext2 or ext3 partitions. (Do not ever use it with a partition that has AFS or another format).

Boot with a live cd or the first cd of Redhat and write "linux rescue".
Do not let the rescue mode to detect the linux partitions, else it would mount them and you do not want to mount the partitions yet, the file system check (e2fsck) can cause severe problems on a mounted partition.

When you are at the rescue mode prompt, write:

# e2fsck -c -c -v -y /dev/hda1
It is important to user "-c -c" (twice) this means that badblocks will scan using a non-destructive read-write test.
"-v" to verbose and see the status of fsck.
"-y" says to answer "yes" to all the questinons from fsck.

REDHAT DVD ISO FILE FREE DOWNLOAD{http://freedownloadzone.org/operating_systems_2.html}

http://freedownloadzone.org/operating_systems_2.html

http://freedownloadzone.org/operating_systems_2.html

http://freedownloadzone.org/operating_systems_2.html

http://freedownloadzone.org/operating_systems_2.html



*********************ALL THE BEST** 

How to Add a new yum repository to install software under CentOS / Redhat Linux

CentOS / Fedora Core / RHEL 5 uses yum for software management. Yum allows you to add a new repository as a source to install binary software.

Understanding yum repository
 
yum repository configured using /etc/yum.conf file. Additional configuration files are also read from the directories set by the reposdir option (default is /etc/yum.repos.d and /etc/yum/repos.d.
RPMforge repository
Usually repository carries extra and useful packages. RPMforge is one of such repository. You can easily configure RPMforge repository for RHEL5 just by running following single RPM command:
# rpm -Uhv http://apt.sw.be/packages/rpmforge-release/rpmforge-release-0.3.6-1.el5.rf.i386.rpm
For 64 bit RHEL 5 Linux, enter:
# rpm -Uhv http://apt.sw.be/packages/rpmforge-release/rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm
Now you can install software from RPMforge.

How do I install 3rd party repository manually?
 
Let us say you would like to install 3rd party repository from foo.nixcraft.com. Create a file called foo:
# cd /etc/yum.repos.d
# vi foo
Append following code:
[foo]
name=Foo for RHEL/ CentOS $releasever - $basearch
baseurl=http://foo.nixcraft.com/centos/$releasever/$basearch/
enabled=1
gpgcheck=1
gpgkey=http://foo.nixcraft.com/RPM-GPG-KEY.txt
Save and close the file.
Where,
[foo] : Repository name i.e. The [main] section must exist for yum to do anything.
name=Foo for RHEL/ CentOS $releasever - $basearch : A human readable string describing the repository name
baseurl=http://foo.nixcraft.com/centos/$releasever/$basearch/ : Must be a URL to the directory where the yum repository’s ‘repodata’ directory lives
enabled=1 : Enabled or disabled repo. To disable the repository temporarily, set the enabled to 0
gpgcheck=1 : Security feature, use GPG key
gpgkey=http://foo.nixcraft.com/RPM-GPG-KEY.txt : GPL file location
Also you need to import the gpg key for the repository as follows:
# rpm --import http://foo.nixcraft.com/RPM-GPG-KEY.txt
Now you are ready to install software from foo repository. For further information refer to yum.conf man page:
$ man yum.conf
$ man yum
Hope this tip will help you to configure repository as and when required

Linux: TMOUT To Automatically Log Users Out

How do I auto Logout my shell user in Linux after certain minutes of inactivity?

Linux bash shell allows you to define the TMOUT environment variable. Set TMOUT to automatically log users out after a period of inactivity. The value is defined in seconds. For example,

export TMOUT=120

The above command will implement a 2 minute idle time-out for the default /bin/bash shell. You can edit your ~/.bash_profile or /etc/profile file as follows to define a 5 minute idle time out:

# set a 5 min timeout policy for bash shell
TMOUT=300
readonly TMOUT
export TMOUT

Save and close the file. The readonly command is used to make variables and functions readonly i.e. you user cannot change the value of variable called TMOUT.
How Do I Disable TMOUT?

To disable auto-logout, just set the TMOUT to zero or unset it as follows:
$ export TMOUT=0
or
$ unset TMOUT
Please note that readonly variable can only be disabled by root in /etc/profile or ~/.bash_profile.

Howto: Upgrade Linux Kernel

How do I upgrade my Linux kernel? I would like to upgrade kernel without compiling from source code i.e. binary upgrade. How do I perform the actual upgrade of the kernel in Linux?

You need to compile kernel only if:
=> You need custom made kernel for specific task such as embedded kernel.
=> Apply third party security patches.
=> You need to apply specific patch to Linux
Upgrade of the kernel in Red Hat enterprise Linux version <= 4.x
If your system is registered with Red Hat Network (RHN), then you can use the up2date command as follows:
# up2date -f kernel
For SMP kernel (multi core or multiple CPU) use command:
# up2date -f kernel-smp
Upgrade of the kernel in Fedora Linux / CentOS / RHEL 5
Use yum command to upgrade kernel:
# yum update kernel
If you have downloaded RPM file use rpm command:
# rpm -ivh kernel*

portnumbers in servers

port number application
21 ftp
22 ssh
23 telnet
25 smtp mail port
53 dns port
67 dhcp server
79 finger command for smtp mail server ETRN finger port
80 http port
110 pop3 port
115 sftp port
123 network time protocal port
143 imap4 port
177 xmanager port tcp
389 ldap port
443 hhtp port (ssl)
445 microsoft active directory and smb protocal port
465 google mail outgoing mail server
636 ldap(ssl)
993 secure internet message access protocalport
1433 sql server port
1434 sql server monitoring port
1521 oracle port
2000 cisco ip phone port
3306 default mysql port
3389 remote desktop port and terminal server port
5900 real vnc default remote control port
6000 tcp port for xmanager port
8080 http internet traffic port

Root user login on VSFTP

As you know ftp servers normally wont allow to login as root user or any of the local user (Example : daemon,bin, sys, nobody…etc) due to security and preventing the ftp servers from ftp brute force scanner attacks. If you still want to enable root user login on vsFTP for some reasons, here is a short tutorial which allows you to do that.

Enabling Root User Login On VSFTP

SSH your server as root and then search for the files ftpusers, vsftpd.users (or) user_list (on Centos the locations should be under the /etc/vsftpd or under /etc). Edit the files on your favorit editor and remove the ” root ” from the list of users. Now edit the /etc/vsftpd.conf file and enable/uncomment the following two lines :

# vi /etc/vsftpd.conf

local_enable=YES
userlist_file=/etc/vsftpd/vsftpd.users (if exist)

Restart the vsftpd server to load with the new configuration.

# /etc/init.d/vsftpd restart
Now try login as root via ftp and see how it goes.

Find Out CPU Architecture Information on Linux

You can use /proc/cpuinfo file or use the lscpu command to get info about CPU architecture.

$ less /proc/cpuinfo

Or

$ lscpu

Disabling USB ports

If you administrating a small or large workstations running with Linux Desktops and want to disable the USB ports for security so that no one can copy the data via pen drive, try the following steps to disable the USB port(s).

Edit the grub.conf and add the following lines(you need to login as root).
# vi /boot/grub/grub.conf

Then add the following lines on the right kernel version

kernel /vmlinuz<your-kernel-version> rhgb quiet nousb

Save and exit the file and reboot the system to disable the USB ports and the boot time.

How To Call Your Friends With Their Own Number....

How To Call Your Friends With Their Own Number....

 Mobile hack to call your friends:

1. Go to  http://www.mobivox.com and register there for free account.


2. During registration, remember to insert Victim mobile number in "Phone number" field as shown below.


3. Complete registration and confirm your email id and then login to your account. Click on "Direct WebCall".


4. You will arrive at page shown below. In "Enter a number" box, select your country and also any mobile number(you can enter yours). Now, simply hit on "Call Now" button to call your friend with his own number.


5. That's it. Your friend will be shocked to see his own number calling him.

Installing Linux Kernal-Based Virtual Machine (KVM) on CentOS 5.4 Server step by step

Step 1. Set SELINUX to “disabled”
# vim /etc/selinux/config
SELINUX=disabled
Step 2: Check that hardware support hardware virtualisation
# egrep '(vmx|svm)' --color=always /proc/cpuinfo
Your output should be something like this
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush
dts acpi mmx fxsr sse sse2 ss ht tm syscall nx pdpe1gb rdtscp lm constant_tsc nonstop_tsc pni monitor
ds_cpl vmx smx est tm2 cx16 xtpr popcnt lahf_lm
.......
If you do not get this output, then we can conclude that your hardware does not support virtualisation
Before you do a yum, make sure you have EPEL Repository enabled. For more information see Red Hat Enterprise Linux / CentOS Linux Enable EPEL (Extra Packages for Enterprise Linux) Repository
Step 3: Install the KVM and virtinst (tools to create virtual machines)
yum install kvm kmod-kvm qemu libvirt python-virtinst
Reboot the System
# shutdown -r now
Step 4: Verify that the kernel has is loaded
# lsmod | grep kvm
the output should be something like
kvm_amd 50452 0
kvm 109264 1 kvm_intel
Check that the KVM is installed
# virsh -c qemu:///system list
Id Name State
----------------------------------
Step 5: Setting up of a Network Bridge so that the VM can be accessed from other hosts on the same network
a. Install the Bridge
# yum install bridge-utils
b. Configure the Bridge. Create the “bridge configuration file”. Ensure the BOOTPROTO, BROADCAST, IPADDR, NETMASK and NETWORK are the same as /etc/sysconfig/network-scripts
# vim /etc/sysconfig/network-scripts/ifcfg-br0
DEVICE=br0
TYPE=Bridge
BOOTPROTO=static
BROADCAST=192.168.50.255
IPADDR=192.168.50.100
NETMASK=255.255.255.0
NETWORK=192.168.50.0
ONBOOT=yes
c. Modify the /etc/sysconfig/network-scripts/ifcfg-eth0. Amend as follows
# Chelsio Communications Inc T310 10GbE Single Port Adapter
DEVICE=eth0
#BOOTPROTO=static
HWADDR=00:xx:00:xx:00:xx
ONBOOT=yes
BRIDGE=br0
#IPADDR=192.168.50.100
#NETWORK=192.168.50.0
#NETMASK=255.255.255.0
d. Disable NetworkManager
# chkconfig NetworkManager off
# service NetworkManager stop
# chkconfig network on
e. Restart the Network
# service network start
f. Verify that the Network Bridge is working
# ifconfig
br0 Link encap:Ethernet HWaddr xx:xx:xx:xx:xx:xx
inet addr:192.168.50.100 Bcast:192.168.50.255 Mask:255.255.255.0
inet6 addr: fe80::210:a7ff:fe05:afeb/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:17 errors:0 dropped:0 overruns:0 frame:0
TX packets:53 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1160 (1.1 KiB) TX bytes:14875 (14.5 KiB)

eth0 Link encap:Ethernet HWaddr yy:yy:yy:yy:yy:yy
inet6 addr: fe80::210:a7ff:fe05:afeb/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:13662 errors:7 dropped:160 overruns:4 frame:0
TX packets:11646 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:15144608 (14.4 MiB) TX bytes:1379942 (1.3 MiB)
Interrupt:74 Base address:0xcc00

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:38 errors:0 dropped:0 overruns:0 frame:0
TX packets:38 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:4308 (4.2 KiB) TX bytes:4308 (4.2 KiB)

virbr0 Link encap:Ethernet HWaddr 00:00:00:00:00:00
inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0
inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:35 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:9987 (9.7 KiB)
Step 6: Installing Virt-Manager on CentOS on a remote or local server
# yum install virt-manager
================================================================================
Package Arch Version Repository
Size
================================================================================
Installing:
virt-manager x86_64 0.6.1-12.el5 base 1.5 M
Installing for dependencies:
e4fsprogs-libs x86_64 1.41.9-3.el5 base 104 k
gnome-python2-gnomekeyring
x86_64 2.16.0-3.el5 base 17 k
gtk-vnc x86_64 0.3.8-3.el5 base 81 k
gtk-vnc-python x86_64 0.3.8-3.el5 base 12 k
libvirt x86_64 0.6.3-33.el5_5.3 updates 2.0 M
libvirt-python x86_64 0.6.3-33.el5_5.3 updates 137 k
python-virtinst noarch 0.400.3-9.el5_5.1 updates 380 k
xen-libs x86_64 3.0.3-105.el5_5.5 updates 156 k
xz-libs x86_64 4.999.9-0.3.beta.20091007git.el5 base 95 k

Transaction Summary
================================================================================
Install 10 Package(s)
Upgrade 0 Package(s)

Total download size: 4.5 M
Is this ok [y/N]:
Step 7: Install Virtual Machines using virt-install
a. Do put an ISO of the Operating System into Server so that you can build the Virtual Machine From. If you only have the disk but not the ISO, you may want to look at “Making Disc Images using mkisofs” from Linux Toolkit
b. Do also take a look at the Guest Support Status from KVM to know what is supported for the version of KVM.
Step 8: Prepare the Virtual Machine
Prepare a Installation Script for easier management.
a. For CentOS Virtual Machine
# vim kvm_centos5.4.sh
virt-install \
--connect qemu:///system \
--name centos5.4_n01 \
--vcpus=2 \
--ram 1024 \
--disk path=/nfs_shared/vms/centos5.4_n01.img,size=40, \
--cdrom=/nfs_shared/ISO/CentOS-5.4-x86_64-bin-DVD.iso \
--network=bridge:br0 \
--accelerate \
--vnc \
--noautoconsole \
--os-type=linux \
--os-variant=rhel5.4 \
--hvm
b. For Windows XP Machine
# vim kvm_winXp.sh
virt-install \
--connect qemu:///system \
--name winxp_n01 \
--vcpus=1 \
--ram 1024 \
--disk path=/nfs_shared/vms/winxp_n01.img,size=25, \
--cdrom=/nfs_shared/ISO/Windows_XP2.iso \
--network=bridge:br0 \
--accelerate \
--vnc \
--noautoconsole \
--os-type=windows \
--os-variant=winxp \
--hvm
Some notes:
Do note that the disk path should be on a shared drive if you are planning to use “migration” from physical nodes to another physical node.
noautoconsole -> No connection to it is started by default although you can make a connection to it via virt-manager.
accelerate -> The VM will runin using kernel acceleration if available.
os-type and os-variant -> Please check the man virt-install for more information on the exact paramters.
Step 9: Run the script
You should see something like this
Starting install...
Creating storage file... | 40 GB 00:00
Creating domain... | 0 B 00:01
Domain installation still in progress. You can reconnect to
the console to complete the installation process.
Step 10: Continue the installation through Virt-Manager Console.
If you are on the graphical console, just type
# virt-manager
you should be able to see the node name. double-clicked the node icon, you should be able to continue the rest of the installation

Disable the Ctrl-Alt-Delete shutdown keys in Linux

On a production system it is recommended that you disable the [Ctrl]-[Alt]-[Delete] shutdown. It is configured using /etc/inittab (used by sysv-compatible init process) file. The inittab file describes which processes are started at bootup and during normal operation. You need to open this file and remove (or comment it) ctrlaltdel entry.
Ctrlaltdel specifies the process that will be executed when init receives the SIGINT signal. SIGINT is the symbolic name for the signal thrown by computer programs when a user wishes to interrupt the process, for example reboot/shutdown system using [Ctrl]-[Alt]-[Del].). This means that someone on the system console has pressed the CTRL-ALT-DEL key combination. Typically one wants to execute some sort of shutdown either to get into single-user level or to reboot the machine.

Disable CTRL+ALT+Del keys
Open /etc/inittab file, enter:
# vi /etc/inittab
Search for line that read as follows:
ca:12345:ctrlaltdel:/sbin/shutdown -t1 -a -r now
And remove the line or comment out the above line by putting a hash mark (#) in front of it:
# ca:12345:ctrlaltdel:/sbin/shutdown -t1 -a -r now
Save the file and exit to shell promot. Reboot system to take effect or type command:
# init q

First we must learn how to install linux

1] Graphical mode installation{DVD}
      2] Text mode installation{DVD}
      3] Kickstart method installation{iso,cd, or network}
      4] via Network Installation
      5] via FTP installation
      6] via http installation
      7] via USB installation

so any one method do practice your self,

y2k>next we see how many partitions required for os installation
        *
TWO PARTITION IS ENOUGH FOR LINUX INSTALLATION
1. /                           ................HERE PUT MAXIMUM SIZE
2.SWAP                .................MULTIPLY BY 2 WITH OUR RAM SIZE [EX:512*2=1024]

why name "linux"

                                                           LINUS TORVALDS

           The name "Linux" comes from the Linux kernel, originally written in 1991 by Linus Torvalds. The main supporting user space system tools and libraries from the GNU Project (announced in 1983 by Richard Stallman) are the basis for the Free Software Foundation's preferred name GNU/Linux.