In this article we are going to check how to disable SELinux in Centos Box.SELinux brings lot of security measures to your Linux box.It will provide an additional level of access control mechanism to files and folders on top of normal Linux security tools.

Sometimes you feel it is necessary or to be handy to have a local yum server in your network.So let’s try to create a local yum server in your network.

This how to article for using yum with a proxy server describe how to configure YUM to work behind proxy server using username and password.If you are behind proxy server then you need to configure yum to pass proxy server.

Linux server configuration file checking commands in brief.These commands are useful for verifying configuration files in Linux server before applying to the server.

important uses of LSOF Command – lsof is a Linux utility which lists the information about files opened by processes.LSOF is one of the powerful tool available for troubleshooting problems.

NAT-Network Address Translation is used to communicate from one network to other network with different sub-net.So your Linux box will act as a gateway and will allow to communicate between two different networks.

Here we are trying to find out how to convert Linux man pages to PDF. Man Pages are most reliable reference available for Linux users and man command remains the easiest way to access those reference pages.

password expiry for users is configuring in /etc/login.defs file.These are the password aging parameters PASS_MAX_DAYS                Maximum number of days a password may be used. PASS_MIN_DAYS                 Minimum number of days allowed between password changes. PASS_WARN_AGE               Number of days warning given before a password expires. By default PASS_MAX_DAYS will be 99999 days that means no password expiry.So [...]

Autoconf is a set of tools which makes your project configurable and portable for running in Linux distributions. Simply, autoconf will help you to create configure script and Makefile for your code. Before going to generate configure script using autoconf, we need to define set of rules and dependencies. We are defining that rules and [...]

Steps: #yum install exim system-switch-mail After successful installation, we need to make some necessary configurations. Switch default MTA(Mail Transfer agent) to exim if it is sendmail or any other application by using system-switch-mail. Then stop sendmail service if it is running and disable in startup. #service sendmail stop #chkconfig  sendmail off And start exim service [...]

The basic network discovery always start with ping utility.So blocking the ping requests will make the system discovery difficult.To disable ping requests ,we just need to add/modify some kernel parameters. What we are doing here is the permanent change. So open /etc/sysctl.conf  and add the following line to /etc/sysctl.conf net.ipv4.icmp_echo_ignore_all = 1 And reload kernel [...]

Building a centralized log host in your network will ease the process of troubleshooting your servers from a single window.Centralized log host will accepts all the log messages from client and store in that server.

tty – tty command  will tells you current terminal. #tty /dev/pts/1 whoami- whoami commands tells you current logged-in username #whoami root which- which command will give you the path of the command #which tty /usr/bin/tty set- set command prints and sets the shell variables or environment variables echo-echo command will prints the output to screen [...]

Environment variables in Unix are a set of dynamic named values that can affect the way running processes will be have on a computer

script is one of the powerful tool available to record a unix terminal session.Start the recording of Unix terminal session with script command.And start doing your important configurations, it will recorded in a file. After completing the task ,you can exit the recording with exit command Example procedure: [root@core-22 ~]# script Script started, file is [...]

What is run level in Unix??? Run level defines the predefined set of operational state for Unix system.The operational state is defined in file  inittab which is located in /etc. init command used to switch between different run levels.init command followed by runlevel will switch system to corresponding runlevel Eg:  init 3 This will switch [...]

First runlevel for Linux system which only one user is allowed to access that root user.Single user mode is useful for fixing some system problem like filesystem errors,recovering root password etc.So these are the steps for entering to single user mode in Linux.This is based on redhat enterprise linux 5( RHEL 5) Steps: Press any [...]

tcpdump is a common command line packet analyzer.It allows the user to intercept and display TCP/IP and other packets being transmitted or received over a network to which the computer is attached.tcpdump works on most UNIX like operating systems. USAGE: #tcpdump                               –Display standard tcpdump output #tcpdump -v ,-vv, -vvv           [...]

First we need to find out which disks and partitions are being used. So we could use the following commands #df -h [This  will display which partitions  are being used] #fdisk -l [This will show which disks are being used and disks that are not mounted.] Now we can start the lvm implementation,we have two [...]

Let see how to install and configure mrtg with this article. Required packages mrtg-2.10.15-1.i386.rpm net-snmp net-snmp-utils Prerequisite: snmp should be configured and running Change the permissions of the directory #chmod 777 /var/www/mrtg Generate a configuration file #cfgmaker –output=/etc/mrtg/mrtg.cfg -ifref=ip –global “workdir: /var/www/mrtg” –global ‘options[_]: growright,bits’ user@192.168.0.10 Edit the configuration file and make the necessary changes. [...]