virtusertable is used to do aliases to virtual domains hosted on the same server. In this case we use  mail1.domain.org as main host and mail2.domain.org as virtual host. Before creating virtusertable mapping ,you need to create a file virtusertable in /etc/mail/.In virtusertable each entry should be a single line.The entry in left hand side denotes [...]

How to mark volume groups as active or inactive in Linux using lvchange command in Linux

Fencing is the disconnection of a node from the cluster’s shared storage. Fencing cuts off I/O from shared storage, thus ensuring data integrity. There are two fencing programs fenced Configured with CMAN/DLM GULM Configured with GULM servers When the cluster manager determines that a node has failed, it communicates to other cluster-infrastructure components that the [...]

Asterisk is a software implementation of a telephone private branch exchange (PBX) originally created in 1999 by Mark Spencer of Digium. Like any PBX, it allows attached telephones  to make calls to one another, and to connect to other telephone services including the public switched telephone network (PSTN) and Voice over Internet Protocol (VoIP) services. [...]

Synergy is software client/server application for several operating systems (GNU/Linux, Mac OS X, Microsoft Windows and more) which allows you to control multiple computers through the same keyboard and mouse. Moreover, your computers will be able to share their clipboards among themselves, enabling you,like, to copy text from a Linux application and paste it into [...]

1. Download jdk from http://java.sun.com/javase/downloads/ into /root/Downloads/ 2. Create a directory ‘java’ in /usr mkdir /usr/java cd /usr/java cp /root/Downloads/jdk-6u<version>-linux-i586.bin . 3. Make the file executable chmod a+x jdk-6u<version>-linux-i586.bin 4. Run java self extracting binary ./jdk-6u<version>-linux-i586.bin The binary code licence is displayed , prompted to agree to its terms.The installer copy files into jdk-6u<version> directory. [...]

selinux is created by National Security Agency. NSA created a project to enforce Mandatory Access Control (MAC) inside the Linux Kernel which is known as Security Enhanced Linux or SELinux

Rsync: rsync is an application used in unix systems which synchronize files and directories between two machines.rsync behaves like rcp(remote file copy),but it much faster than rcp.because rsync sends the differences in the files instead of sending entire files. Servers are SERVER_SOURCE & SERVER_DESTINATION Configure SSH key authentication In SERVER_DESTINATION open sshd_config file vi /etc/ssh/sshd_config [...]

Cacti is a network graphing tool similar to MRTG.It is a complete front end to RRDtool,it stores all of the necessary information to create graphs and populate them with data in MySql database.The front end is completely PHP driven. Requirements MySql server NET-SNMP server (SNMP is used for network management) PHP with net-snmp module Web [...]

Before upgrading you should have a good backup of existing nagios installation and configuration files.If anything goes wrong,then this will allow you to rollback to your old version. Nagios upgrading don’t even need root access.We can do this as ‘nagios’ user. Become nagios user by su or sudo command su -l nagios Remove the following [...]

By using nagios we can monitor private services & attributes like Memory usage CPU load Disk usage Service stats Running processes etc Monitoring private services or attributes of a windows machine requires an agent on it.This agent act as a proxy between the nagios plug-in that does the monitoring and the actual service or attribute [...]

WebDAV stands for web based Distributed Authoring and Versioning.And it is a set of extension to the http protocol that allows users to directly edit files on the apache server so that they do not need to be downloaded/uploaded via FTP.apache Enabling WebDAV on apache web server includes the following steps Install mod_dav module Edit [...]

Nagios is a popular open source computer system and network monitoring software application. It watches hosts and services, alerting users when things go wrong and again when they get better. Installation includes the following steps Create user account for nagios #useradd nagiosnagios #passwd nagios Create  group named ‘nagioscmd’and add users naios and apache to this [...]

RAID is an acronym for Redundant Array of Independent Disks. With RAID enabled on a storage system you can connect two or more drives in the system so that they act like one big fast drive or set them up so that one drive in the system is used to automatically and instantaneously duplicate (or mirror) your data for real-time backup.

Creating user and group for mysqlmysql #groupadd mysql #useradd -g mysql mysql Get source from http://dev.mysql.com/downloads/mysql/5.0.html#source Unpack the package using the following command #tar -xvf mysql-5.x.x.tar.gz #cd mysql-5.x.x #./configure –prefix=/usr/local/mysql-5.x.x Then compile & install #make #make install Then create a symbolic link ‘mysql’ pointing to mysql-5.x.x(Installation directory) #ln -s /usr/local/mysql-5.0.37/ /usr/local/mysql  (Generally mysql installation path [...]

Get the source from http://www.php.net/download.php (php-5.x.x.tar.gz) Prerequisites Apache webserver Mysql Installation Goto the directory use this command to unpack the file tar -xvf php-5.x.x.tar.gz cd php-5.x.x ./configure –prefix=/usr/local/php –with-apxs2=/usr/local/apache2/bin/apxs –with-mysql=/usr/local/mysql * –prefix specifies the location where PHP is to be installed . * –with-apxs2 pointing to bin/apxs in the apache installation directory. * –with-mysql to [...]

Login as root user Enter grub mode: # grub Use md5crypt to encrypt password: grub> md5crypt Password: ****** Encrypted: $1$jxcdN0$hVHViq1aiPf8FziuGJGZp0 Copy encrypted password Exit grub mode: grub> quit Modify file /boot/grub/grub.conf: vi /boot/grub/grub.conf Insert this line after splashimage  “password –md5 $1$jxcdN0$hVHViq1aiPf8FziuGJGZp0″ splashimage=(hd0,0)/boot/grub/splash.xpm.gz password –md5 $1$jxcdN0$hVHViq1aiPf8FziuGJGZp0 then save& exit /boot/grub/grub.conf

Get linux kernel version with this command # uname -a Now perform this steps # cd /usr/src/linux # make mrproper # make oldconfig # make bzImage # make modules # make modules_install # make install # reboot In new Redhat systems, the headers are included in the kernel-devel package and the compile process is a [...]

In this how to we are trying go through the steps involved in software installation from source.
The software installation from source includes the following steps

RT-Linux is an operating system in which a small real-time kernel coexists with the Linux kernel which was originally developed by Victor Yodaiken at the New Mexico Institute of Mining and Technology.RTLinux supports hard real-time operation through interrupt control between the hardware and the operating system. Interrupts needed for deterministic processing are processed by the [...]