Saturday 10 December 2016

How to Check the lock status of any Linux Account

Now one single command to see the lock status of the user:

Tuesday 29 November 2016

pam_tally2 command – lock & unlock ssh failed logins

Check users login attempts using pam_tally2 command:

How to Enable Passwordless Authentication with SSH

Note: - Node1 is the source and Node2 will be the destination machine.

Add a User and Grant Root Privileges on CentOS 7

Step 1: Add the User

Add new user use the below command:

Thursday 19 May 2016

How to install GNOME Desktop in Centos 6.x.x minimal installation

This blog provides the steps to add the GNOME Desktop to a CentOS minimal installation where the OS was installed without the X Window System/GUI.

Monday 25 April 2016

How to change max_connections setting in MySQL

Error:  "too many connections"

Solution:The default setting for max_connections is 151.

Monday 18 April 2016

How to install Bugzilla 4.2 on CentOS 7

Bugzilla is an advanced bug tracking system, developed by the Mozilla Foundation. Bugzilla allows you to track defects and code changes in applications, allow communicating in your dev team easily and submitting and reviewing patches.

Tuesday 12 April 2016

How to configure Self-Signed SSL Certificate in Apache HTTP Server

Apache HTTP Server HTTPS secure connection using Self-Signed SSL on Apache.

How to Disable SELinux on CentOS 7

SELinux, or Security-Enhanced Linux, is a set of security modules which are loaded in to kernel to improve security on accessing services/files which improve security. SELinux was initially released as a collaborative between Red Hat and the National Security Agency. The SELinux kernel separates policy and decisions inside the kernel to distribute levels of protection and prevent a total security breach.

How to add or change hostname in RHEL7/CentOS 7

By default, while installation the server is started with the default host name as localhost.localdomain. Host name for a system is like an identity for that system to makes system management and also we can use host name to access the system over the LAN.

Tuesday 22 March 2016

How to Install Webmin on CentOS/RHEL 7

Webmin is a web-based interface for system administration for Centos / RHEL and mostly other distribution as well. User accounts, Apache, DNS, file sharing and other services can be managed by web browser using webmin tool.

Gitlab Server Community Edition (CE) Backup and restore

Backup Steps for Gitlab Omnibus installations:

A backup creates an archive file that contains the database, all repositories and all attachments. The filename will be [TIMESTAMP]_gitlab_backup.tar and default backup/restore directory is var/opt/gitlab/backups. This timestamp can be used to restore an specific backup.  You can only restore a backup to exactly the same version of GitLab Server. You need to keep a separate copy of /etc/gitlab/gitlab-secrets.json . This file contains the database encryption key used for two-factor authentication.

How to install sar, sadf, mpstat, iostat, pidstat and sa tools on CentOS / RHEL

Install sar, sadf, mpstat, iostat, pidstat and sa tools on CentOS  / RHEL

The following command can be used to install sar, sadf, mpstat, iostat, pidstat and sa tool:

Saturday 12 March 2016

How to Install Gitlab on CentOS/RHEL 7

GitLab is a open source web-based Git repository manager and issue tracking features. Git repository provides user/group management, code reviews, issue tracking, activity feeds and wikis. It comes with GitLab CI for continuous integration and delivery.

Ho to Install Gitlab Server dependencies

For Gitlab operation we need to configure mail service on Gitlab server. Use any mail services like sendmail, postfix or other SMTP servers etc. In this post we are using postfix email service for sending emails.

Friday 4 March 2016

Sendmail issue on CentOS 7 (Log permission denied in /var/log/maillog)

Apache/PHP on CentOS 7 unable to send emails using sendmail

See log in /var/log/maillog file should shows following error:

Tuesday 23 February 2016

How to install Java 7/jdk1.7 in Centos7/RHEL7

Step 1: Download java from oracle official site:

Download “jdk-7u79-linux-x64.rpm” from here and save the package to /opt directory or change the directory where you downloaded the package:

Sunday 21 February 2016

DHCP: DORA Process

It is important to understand how DHCP uses the DORA process to operate. Dynamic Host Configuration Protocol (DHCP) is used to automatically assign IP address to client machines. Without DHCP, you would have to go to each machine and manually enter the address. DHCP is broadcast-based, using ports.

How to install Java8/jdk1.8 in Centos7/RHEL7

Step 1: Download java rpm package from oracle official site:

Download “jdk-8u60-linux-x64.rpm” from here and save the package to /opt directory or change the directory where you downloaded the package:

Tuesday 16 February 2016

How to Install and Configure NTP Server on CentOS 7

Network Time Protocol – NTP- is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks which runs over port 123 UDP at Transport Layer. In operation since before 1985, NTP is one of the oldest Internet protocols in current use. NTP was originally designed by David L. Mills of the University of Delaware, who still oversees its development.

Thursday 11 February 2016

How to install Apache Tomcat Natives on CENTOS7/RHEL7

Step 1: To install Tomcat Natives first need to install prerequisites compilers and development tools:

Tuesday 9 February 2016

Recover corrupt rpm database on RHEL/Centos/Fedora

First thing take a backup of the existing rpm database. This is located in /var/lib/rpm. Depend on used distribution:

Sunday 7 February 2016

Name based Virtual Hosting

Step 1: Create Dir for Document root to Keep web pages for multiple domains and copy webpagescontents on it:

Saturday 6 February 2016

How to Recover MySQL database server password

Step 1: Stop Mysql Server: 

Friday 5 February 2016

PostgreSQL server allow to connect from remote clients

Step 1: You have to make PostgreSQL listening for remote incoming TCP connections because the default settings allow listening only for connections on the loopback interface. To be able to reach the server remotely you have to add the following line into the file /etc/postgresql/9.3/main/postgresql.conf:
listen_addresses = '*'

Saturday 16 January 2016

MySQL Server 5.7 Installation and Basic operations

1) Configure local yum or Registered yum repository

2) Download MySQL Server Repository rpm from below link: