Author: Rahul

.htaccess stands for “hypertext access”. This is the default Apache directory level configuration file. .htaccess can be used to secure a particular directories in web server. One of the most common uses is to require user authentication in order to serve certain web pages. Create .htaccess File. First create a .htaccess file in your website document root to protect entire site or in specific directory and add following content. AuthType Basic AuthName “Secure Content” AuthUserFile /home/myuser/public_html/.htpasswd require valid-user AuthType: defines the type of authentication. Basic means there is no encryption and the password hash is sent as clear text. AuthName:…

In the realm of Linux, the at command stands as a powerful yet often overlooked tool for scheduling tasks. This utility is specifically designed for one-time job scheduling, allowing users to execute commands or scripts at a later time. This article delves into the functionality, usage, and practical applications of the at command, providing insights into how it can streamline workflow and automate tasks in a Linux environment. Understanding the ‘at’ Command The at command in Linux is a job scheduling tool, distinct from the more commonly known cron. While cron is used for recurring tasks, at is the tool…

The find command is a versatile and powerful utility in Linux, allowing users to search for files and directories based on various criteria such as name, type, size, modification time, and more. Mastering the find command can significantly improve your efficiency and effectiveness when working with Linux systems. This article will provide a comprehensive guide to the find command, accompanied by practical examples. Find Command Syntax and Options The basic syntax of the find command is as follows:

PATH: The directory in which to start the search. EXPRESSION: The search criteria, including options and tests. Some common options include:…

Its a good practice to enable email alerts in your keepalived configuration. By using this keepalived service will always inform users whenever server switches from master to slave or slave to master for each VRRP instance. Below steps will help you to how to enable email alerts in Keepalived. Steps to enable email alerts: Step 1: Edit keepalived configuration file. # /etc/keepalived/keepalived.conf Step 2: Add below entry in global settings. global_defs { notification_email { [email protected] } notification_email_from [email protected] smtp_server mail.tecadmin.net smtp_connect_timeout 30 # …… Other configuration here ……. } Step 3: Add smtp_alert in each VRRP instances. vrrp_instance VI_1 {…

HTTPD (Hypertext Transfer Protocal Deamon) is a web server widely used with CentOS and Redhat Linux.It serves the webpages on clients requests. It is developed by Apache foundation. HTTPD is very easy in install and configure. Installing httpd using yum. # yum install httpd Default httpd basic configuration are as following. Configuration file: /etc/httpd/conf/httpd.conf Port: 80 Document root: /var/www/html Log file location: /var/log/httpd Setup virtual host in httpd configuration file Append below setting in httpd configuration file <VirtualHost *:80> ServerName www.tecadmin.net ServerAdmin [email protected] DocumentRoot /var/www/html </VirtualHost> Start httpd service # service httpd start Confugure httpd to start on system boot.…

In the Linux filesystem, all the files have 3 special permission used for different purposes. In this tutorial, we will discuss about Sticky bit, SUID, and SGID file permissions in the Linux file systems. What is Sticky Bit? The sticky bit is used to indicate special permissions for files and directories. If a directory with sticky bit enabled will restrict deletion of the file inside it. Any file has the sticky bit set, can be removed by its owner, the root, or who has to write permission on it. This is useful for shared or publically accessible directories like /tmp.…

A shell is a command line interpreter. Its a special program which takes input from standard input devices, convert it to machine language and send to OS. After processing by OS, send result back to shell. Shell again translate it to human readable format and send results to output devices. Linux Shells: Bash Shell ( Born Again Shell ) : This is most common shell used by linux now a days. Bash sell is developed by Sir Brian Fox and Chet Ramey. CSH ( C Shell ) : The C shell’s syntax and usage are very similar to the C…

The Ext3 and Ext4 filesystem includes support of ACLs on files and directories. ACL provides more control permissions on file than standard three access categories (owner, group, and other ). Using ACL you can provide permission to a specific user or group to file. Before working on ACL make sure that ACL is enabled on the mounted file system. You can enable it during mounting the filesystem with the ACL option. Use the following command Check if ACL is enabled on the filesystem or not. sudo mount Output /dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw,noatime,acl) Enable ACL by remounting file system…

MySQL is a relational database management system, used for storing data in form of tables and records. You can insert, modify or retrieve data using SQL statements or programming languages. It allows us to create new users and grant permissions on tables of the database. As a good practice always use a separate user for all databases. This will ensure that the application can’t access other applications’ databases. The purpose of this tutorial is to create a new user in the MySQL server and grant permissions to databases. This tutorial includes instructions to create users, and grant permission on all…

Postfix is fast and popular SMTP server widely used. The main job of postfix is to relay mail locally or to the intended destination outside the network. Some of the most popular SMTP servers are Sendmail, Postfix, and Qmail. By default, Sendmail comes pre-installed with CentOS/RHEL 5. We will need to remove it and install Postfix. You may also like: Install Postfix on Ubuntu Step 1 – Install Postfix If Postfix not already installed on your machine, Install it using the following command. Also, remove sendmail if already installed. yum remove sendmail yum install postfix Make postfix as default MTA…