In Linux you can use faillog command to display failed login attempts or you can set login failure limits. faillog formats the contents of the failure log from /var/log/faillog database / secure log file. It also can be used for maintains failure counters and limits. For RHEL/CentOS Linux 5.x, you need to modify /etc/pam.d/system-auth file to monitor or track failed login attempts. You need to...

As you login as “root” right from booting the system, all the privileges are set to root, what makes your system more vulnerable to your own mistakes and those wishing to enter your system. As you login as normal user, the privileges are limited, thus it´s safer. To be able to do administrative tasks you can temporally login as root using “su” in a console/terminal, that way the root privileges ...

YUM is an interactive, rpm based, package manager. It can automatically perform system updates, including dependency analysis and obsolete processing based on "repository" metadata. It can also perform installation of new packages, removal of old packages and perform queries on the installed and/or available packages among many other commands/services (see below). yum is similar to other high level package ...

If you run a dual-boot system with Linux and Windows, and reinstalling Windows XP after OS corrupt.  Windows XP will wipes over write grub entry or writing MBR sector. To recover GRUB, STEP 1: Boot off the Live CD enter into rescue mode, STEP 2: Open a Terminal and type in the following commands, noting that the first command will put you into the grub “prompt”, and ...

PowerDNS is a DNS server, written in C++ and licensed under the GPL. It runs on most Unix derivatives and on Microsoft Windows. PowerDNS can be managed through a web interface (PowerAdmin). Install MySQL, # yum install mysql* -y After installation, start it and create system startup links for MySQL. # service mysqld start; chkconfig mysqld on If you want to set root password, # mysqladmin -u root...

Linux kernel has PC speaker bell driver called pcspkr.ko. It is responsible for generating beeps while users are working on Shell Prompts ( Both Virtual and GUI Terminals ). If you don't like it, simply remove driver from kernel. Login as a root and type the following command to unload the driver: # rmmod -v pcspkr Sample output: rmmod pcspkr, wait=no We...

By default, MySQL only allows connections from the localhost address – 127.0.0.1. The configuration file is usually found in /etc/my.cnf. To switch MySQL to listen on TCP, Open /etc/my.cnf or /etc/mysql/my.cnf. # vim /etc/my.cnf Modify line as below # bind-address  = 127.0.0.1 Save and Exit the file. Now restart the database server by executing, # /e...

When you install a dual-boot of Linux, one of the frustrating things that you’ll immediately notice is that Linux is set as the default operating system in the Grub loader. If you want to change default Operation System instead of Linux, there’s an easy way to switch back to using Windows as the default. Open /boot/grub/menu.lst, # vim /bo...

You may have heard of a server system called LAMP, and wondered what it is. Well, the answer is that LAMP isn't any one thing on its own - it's actually a combination of four technologies. Together, the LAMP technologies form the most popular overall server system on the web today. LAMP is short for Linux, Apache, MySQL, PHP. This will guide you to install LAMP server on your Linux System. Note: I...

SARG – Squid Analysis Report Generator Configuration is a tool that allow you to view “where” your users are going to on the Internet. SARG provides many information about Squid users activities like, times, bytes, sites, etc… Download latest version of SARG from here. # wget http://...

The Multi Router Traffic Grapher (MRTG) is a network or resource monitoring tool used by System Administrators across the Globe. MRTG generates HTML pages containing PNG images, which provides a real time visual representation of network traffic and system resources. STEP 1: Install MRTG with required packages # yum install mrtg net-snmp net-snmp-utils -y STEP 2:...

Mozilla Firefox is a free and open source web browser descended from the Mozilla Application Suite and managed by Mozilla Corporation. As of October 2010, Firefox is the second most widely used browser, with 30% of worldwide usage share of web browsers. In Germany, Firefox is the most popular browser with 60% usage says Wikipedia. To install Firefox 4 on Fedora Linux, # vim ...

Do you want to create a document using windows fonts in Linux? No problem, please install windows fonts using one of mentioned method. Method 1: Copy the *.ttf (True Type Fonts) fonts like Arial, Tahoma, Verdana, Courier New and Times New Roman from the windows partition to the fonts:// location in nautilus. Method 2: For Ubuntu users, and since Ubuntu does not have a...

 In RedHat/CentOS/Fedora, software are packaged in .rpm format. rpm is a powerful Package Manager, which can be used to build, install, query, verify, update, and erase individual software packages. A package consists of an archive of files and meta-data used to install and erase the archive files. The meta-data includes helper scripts, file attributes, and descriptive information about the package. Packages...

Anyone who has physical access to the keyboard can simply use the Ctrl Alt Delete key combination to reboot the server without passing any authentication credentials to server. To disable Ctrl Alt Delete, update /etc/inittab and make sure following line is commented out: # vim /etc/inittab # ca::ctrlaltdel:/sbin/shutdown -t3 -r now Save and exit...

For mysql, the system administrator user is called root. We will use the mysqladmin utility from a command line to set the new password. Default password is not secured at all. By default in RedHat, Fedora and Centos default password is null. So it is always better to set root password. To set root password, # mysqladmin -u root password XyZ@aBc@123 # mysqladmin -u root -h ...

If you are using Linux Desktop Operating System and do not want to set up an email server, use GMail account to relay emails. On Desktop OS, we can use GUI Email Clients, which supports POP3/IMAP to send an email but how about /usr/bin/mail or from cmd prompt? To fulfil your requirement, you need to install a simple program called ssmtp. It accepts a mail stream on standard input...

RRDtool is the Open Source industry standard, high performance data logging and graphing system for time series data. Use it to write your custom monitoring shell scripts or create whole applications using its Perl, Python, Ruby, TCL or PHP bindings. RRDTOOL is required by many network monitoring utilities like cacti, nagios & many others. To install RRDTool CentOS/Red Hat, # wget...

To restricts Users from uploading File Size, we can configure Apache with LimitRequestBody Directive. You can add this directive using .htaccess file or httpd.conf file under virtual host or directory configuration options. You can set value (in bytes) from 0 (unlimited) to 2147483647 (2GB) that are allowed in a request body. For example, limit /var/www/html/linuxarticles.org/uploads to 200K,...

You can easily block SSH server attacks including dictionary based attacks and brute force attacks using a Python based script - DenyHosts. It analyzes the sshd log messages to determine what hosts or IPs are attempting to hack into your system. STEP 1: Enable Rpmforge Repo in your system, For 32bit CentOS / RHEL Linux enter: # rpm -Uhv...

MySQL is a simple SQL shell (with GNU read line capabilities). It supports interactive and non interactive use. When used interactively, query results are presented in an ASCII-table format. When used non interactively (for example, as a filter), the result is presented in tab-separated format. The output format can be changed using command options. After Installation of MySQL on Linux System, start it by, #...

Backing up MySQL database is a very important system administration task, and should generally be run automatically from cron. We will use the mysqldump utility included with mysql to dump the contents of the database to a text file that can be easily restore. # mysqldump -h localhost -u root -p root_password DataBase > DB_name_Bkp.sql This will generate a text file containing ...

  This article will guide you through the necessary steps to install ipw3945 wireless adapter on a CentOS / RHEL based distribution. Before we start, make sure that you have rpmforge repository configured. If you do not have, download it from here. # wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el5.rf.i386.rpm # rpm -ivh...

SparkleShare is a syncing and collaboration tool that shines by its absence. it's designed to get out of your way, to make sharing documents and collaboration easier, and to make peers aware of what you are doing says its project site. With SparkleShare, you are given an option to host your remote folder on your own server, Github, Gitorious, The GNOME Project. Sharing...

After downloading ISO file from Fedora/CentOS, you can check the integrity of the ISO-file with a checksum, the md5sum. The mirror will offer you a separate text file to download with a 128 bit string of characters. This string has to be exactly the same as the one you get when you do: # md5sum file.iso 0c0f8ff9b6fb60a4778288de0d9e7f46  file.iso We assume that, you have downloaded ...