Inside Linux TCP: From Handshake to Reset or Close
TCP is the backbone of network communication in Linux systems. It’s a connection-oriented protocol that ensures reliable data exchange between a sender and a...
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2025
RabbitMQ Monitoring: Pushing Queue Metrics to Elasticsearch with Python script
Monitoring RabbitMQ queues is critical for maintaining the health and performance of the RabbitMQ distributed system. This post is about a Python script that...
Scalable CI/CD with Jenkins and Docker Cloud Agents
A Jenkins cloud agent using Docker refers to dynamically provisioning Jenkins build agents (also called slaves or nodes) in Docker containers—typically on de...
Implementing Mutual TLS (mTLS) Authentication with OpenSSL: A Step-by-Step Guide
This article explores mutual Transport Layer Security (mTLS) authentication and how OpenSSL can facilitate its implementation. Also known as client-server au...
2024
Unassigned shards in Elasticsearch 7 and 8
There are multiple reasons why shards might get unassigned, ranging from misconfigured allocation settings to lack of disk space.
Percona XtraDB Multi-Master Replication cluster setup between 3 nodes
This guide describes the steps to establish a Percona XtraDB Cluster v8.0 among three Ubuntu 22.04 nodes.
Site-to-Site VPN between Mikrotik router and Ubuntu 22.04 through strongSwan using IPsec IKEv2
We will configure a site-to-site IPsec IKEv2 tunnel between the Mikrotik Router and the StrongSwan server. This will enable secure communication between devi...
2023
Monitor HA Cluster running Pacemaker and Corosync using Prometheus and Grafana using Docker
We will use Grafana with prometheus in container to monitor High availability cluster running by Pacemaker and Corosync.
GFS2 Filesystem setup in RHEL8 with Pacemaker and Corosync
We will configure Pacemaker/Corosync to enable the sharing of a disk between two nodes through the GFS2 clustered filesystem.
SAML Authentication for AWS OpenSearch with Okta and Role mapping
We are going to set up IdP-initiated (Okta) SAML authentication for AWS OpenSearch. We will create two Okta groups: “opensearch-admin” and “opensearch-user,”...
2021
Ansible Lab Environment setup in Docker container
For ansible lab environment setup, first I will generate ssh key for non-root user and then create a Dockerfile to build a docker image. After that, we will ...
Add and remove nodes in your Elasticsearch Cluster
I will be adding a new node elk-04 in the existing 3 nodes Elasticsearch cluster and again remove it later.
HAProxy configuration for Windows Exchange Server 2016/2019
HAProxy is a free, very fast and reliable solution offering high availability, load balancing, and proxying for TCP and HTTP-based applications. It is partic...
Ansible: To use the ‘ssh’ connection type with passwords, you must install the sshpass program
“To use the ‘ssh’ connection type with passwords, you must install the sshpass program” to resolve this error message, you have to install sshpass package in...
Enable Outlook 2013/2016/2019 to use Transport Layer Security (TLS) 1.1 and 1.2 in windows 7
If u have an older windows 7 pc from where you want to connect your mail server through outlook 2013/2016/2019 and your mail server only supports TLS 1.2 and...
Ansible Playbook to deploy user with SSH Key
We will create a new user with sudo privilege and deploy it with their SSH Public Key to all the targeted hosts through ansible-playbook. After that, he/she ...
OpenLDAP Monitoring - Nagios, Cacti and OpenLDAP Exporter
We are going to monitor OpenLDAP in our CentOS and Ubuntu servers. After that, we will be able to get an alert from Nagios and also visualize it through Cact...
OpenLDAP MirrorMode Replication & MDB Backend in CentOS 7
In this tutorial, We will show MirrorMode replication between 2 CentOS 7 servers who’s backend is mdb. We will also setup mdb backend for our OpenLDAP storage.
How FreeRADIUS handles Access-Request packets
FreeRADIUS is the most popular and the most widely deployed RADIUS server in the world. Remote Authentication Dial-In User Service (RADIUS) is a client-serve...
Sync NPS (Network Policy Server) configs between multiple servers
Network Policy Server (NPS) is the Microsoft implementation of a Remote Authentication Dial-in User Service (RADIUS) server and proxy.
Windows Machine Monitoring - Exchange, AD, DNS
If you are a system administrator, you might have to monitor Windows PC’s, Exchange Server, Active Directory and DNS Server. For this tutorial, I am using wi...
Use OpenLDAP TOTP as authentication for VPN
For this setup, we will be using FreeRADIUS and compiled OpenLDAP from source along with the TOTP (Time-based One Time Password ) module on CentOS 7. We will...
Adding custom attributes in Active Directory
Schema is an Active Directory component, that defines Active Directory database structure. The schema consists of Object Class and Object Attributes. In this...
Manually building FreeRADIUS 3.0.21 with the rlm_sql_oracle module
We are going to manually build FreeRADIUS version 3.0.21 with ORACLE Module.
2020
Network Traffic Analysis using ElastiFlow
Introduction (NetFlow, IPFIX, sFLOW) Network monitoring is a systematic effort to monitor parameters of a computer network in order to detect issues that deg...
Binding privileged port 514 to Logstash 7.10.0
Sometimes there comes a scenario where you need to receive syslog traffic in the default port 514 in your logstash server. But as we know ports in range 1 t...
NextCloud 19.0.3 Installation with AD, Nginx, Redis, OnlyOFFICE, ClamAV and Cryptomator
We will install NextCloud version 19.0.3 in CentOS 7 along with Clamav version 0.102.4, MySQL DB version 8, PHP 7.4, Redis version 3.2.12 and Nginx as web se...
Confluence 7.8.3 Installation with Nginx and connect with LDAP Directory(AD) on CentOS 7
Confluence is a collaboration wiki tool used to help teams to collaborate and share knowledge efficiently. We will be installing Confluence 7.8.3 version on ...
Citrix XenServer 7.1 CentOS VM’s not starting after Kernel update
After I update my CentOS 7 VM kernel, the new kernel stopped booting on my XenServer hypervisor. I’ve been using XenServer version 7.1
Monitoring ElasticSearch Cluster using Prometheus and Grafana
We are going to monitor our production ElasticSearch Cluster using elasticsearch exporter plugin and store those metrics on the Prometheus server and later v...
Monitoring PHP-FPM Pools through Prometheus and Grafana on CentOS 6 and 7
We are going to monitor metrics of our PHP-FPM pools through phpfpm_exporter and store those metrics on the Prometheus server and visualize it through Grafan...
Install SmokePing 2.7.3 on CentOS 7
Smokeping Version 2.7.3 setup on CentOS 7
Compile PHP 7.3.13 on CentOS 7 with OCI8 and MongoDB extension.
Compiling PHP version 7.3.13 with OCI8 and MongoDB extension on Centos 7.
How to enable TLS 1.3 on Nginx with OpenSSL Centos 7
Here, we are going to enable TLS 1.3 on CentOS 7.
Docker Compose file for MySQL and phpMyAdmin
Here we are going to deploy MySQL and phpMyAdmin container through Docker compose file and also access the MySQL container from the Docker host MySQLWorkbench.
How to Install YOURLS on CentOS 7 using NGINX + HTTPS
Check yourls.org! Learn more tweaks in the Wiki documentation.
2019
Upgrading Firmware on Cisco UCS C-240-M3 Server using HUU (Host Upgrade Utility)
Follow below steps: Step 1: Download the HUU(Cisco Host Upgrade Utility) ISO software. Login with your credential and navigate to the following URL:cisco ...
How to change LVM Volume Group Name and Troubleshoot “dracut-initqueue timeout error” in CentOS 7
Follow the below steps to change Volume Group Name. Here I’m going to change my VG name from centos to fedora-01
Install GitLab Community Edition (CE) 11.10, Deploy SSL and Authenticate with ActiveDirectory on CentOS 7
Installing Gitlab CE 11.10 and authenticating with AD
Increase RAM for XenServer VM’s through Command Line Interface
Increasing RAM through CLI in XenServer VM’s
2018
cPanel/WHM apache log to remote syslog server
cPanel/WHM Dom logs to remote syslog server
inode usages in cPanel /WHM Server
If your inode space is full in your cPanel/WHM server then follow below steps to clear the usages.
Enable/Disable Dell iDRAC7 web service from SSH
Enable/Disable Dell iDRAC7 web service using racadm command via SSH.
Move MySQL data to another folder cPanel/WHM
Change MySQL folder in cPanel/WHM Server.
Add VirtualDisk on Xen VM using XE command line
Steps to add VirtualDisk through XE command line.
2017
Installation of NagiosQL 3.3.0 on CentOS 7
Installing NagiosQL 3.3.0