Introduction Learn how to safely remove old kernels on CentOS , RHEL , and Fedora to free up space and improve system performance. Step-by-step guide with best practices for maintaining your Linux system. As you continue to update and upgrade your Linux system, particularly on distributions like CentOS, RHEL, and Fedora, old kernels can accumulate over time. While these kernels are essential for booting your system, having too many can clutter your boot menu and consume valuable disk space. This guide will walk you through the process of safely removing old kernels from your system without risking stability, ensuring that your Linux machine runs smoothly and efficiently. Why Should You Remove Old Kernels? The Problem with Accumulating Kernels Linux kernels are the core of the operating system, responsible for managing hardware and system processes. Every time you update your system, a new kernel may be installed, but the old ones aren't automatically removed. This can lead to seve

Introduction In this tutorial, we will explore how to install and configure AIDE (Advanced Intrusion Detection Environment) on CentOS. AIDE is a powerful tool designed for monitoring changes to files on the system, helping you detect unauthorized access and modifications.  Ideal for system administrators and security professionals, this guide will provide step-by-step instructions to ensure a successful setup of AIDE on your CentOS system. By the end of this tutorial, you will have a robust intrusion detection system in place, capable of providing detailed reports about the integrity of your files and system security. What does Aide mean AIDE is one of the most popular tools for monitoring the server changes in a LINUX based system.  It call as Advanced Intrusion Detection Environment. Install AIDE on Centos $ sudo yum install aide Check AIDE Version on your system $ sudo aide -v Configure AIDE $ sudo cp /etc/aide.conf /etc/aide.conf_BK Add lines not check /tmp and /pro

In this tutorial, Things to Do After Fresh Installation Fedora 30. Let do it! TO DO 1. Update your Fedora Always keep your system updated to the latest version of packages. $ sudo dnf update 2. Change the hostname $ sudo hostnamectl status # view current hostname $ sudo hostnamectl set-hostname --static "VivoS15" # set up new hostname 3. DNF tweak edit /etc/dnf/dnf.conf file $ sudo cp /etc/dnf/dnf.conf /etc/dnf/dnf.conf_ORIG [huupv@localhost ~]$ cat /etc/dnf/dnf.conf [main] gpgcheck=1 installonly_limit=3 clean_requirements_on_remove=True fastestmirror=true deltarpm=true 4. Install RPM fusion repository $ sudo dnf update --refresh $ sudo dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm $ sudo dnf install https://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm 5. Player and codecs $ sudo dnf install youtube-dl vlc $ sudo dnf in

Introduction Welcome to our detailed guide on how to check for open and closed SSH ports. In today's networked world, maintaining secure server connections is critical. Secure Shell (SSH) is a network protocol that provides administrators with a secure way to access a remote computer.  However, ensuring that your SSH ports are configured correctly is essential to prevent unauthorized access and breaches.  This tutorial will provide you with step-by-step instructions on using various tools to determine the status of SSH ports on your system. Whether you're a seasoned system administrator or a novice user, these skills are fundamental to managing and securing your network connections. In this tutorial, How to checks all ports if they are closed or open and if the current ssh version? Using nmap command. Read man nmap page. First, you need to install nmap . For ubuntu $ sudo apt-get install nmap For centos $ sudo yum install nmap For example, checks for open/closed ports

Introduction Security is a top priority in any system, and email is no exception. Zimbra FOSS offers a robust open-source email solution, and setting up two-factor authentication (2FA) is a crucial step to enhance security. This article will guide you through the process of setting up 2FA on Zimbra Zimbra FOSS in a detailed and easy-to-understand manner, ensuring your email accounts are better protected against potential threats. How to Set Up Two-Factor Authentication on Zimbra FOSS Look like Buy Now The work will consist of the following parts: A patch to the login screen to support entering the 2FA code. PrivacyIDEA and PrivacyIDEA LDAP Proxy docker containers to run and maintain the 2FA toekens on your Zimbra* Zimlet for integrating in the web-ui of Zimbra (SOAP based) with extension on the server (java soap api) Install documentation All released under GNU GPLv2. Conclusion Implementing two-factor authentication on Zimbra FOSS not only helps protect your emai

In this tutorial, How to configure Leverage browser caching for nginx. What does Leverage browser caching mean? Page load times can be significantly improved by asking visitors to save and reuse the files included in your website. Reduces page load times for repeat visitors Particularly effective on websites where users regularly re-visit the same areas of the website Benefit-cost ratio: high Access needed You should add that inside of an existing server block. For example, I will add that inside server block /etc/nginx/sites-enabled/default file. server {     listen       80;     server_name  localhost;     location / {         root   /usr/share/nginx/html;         index  index.html index.htm;     }         location ~* \.(js|css|png|jpg|jpeg|gif|ico)$ {             add_header Cache-Control "public, no-transform";             expires         7d;     } } You can test speed up site On GTmetrix

You can Bypass Two-Factor Authentication and Automate Phishing Attacks by New Reverse Proxy Tool call Modlishka. A Polish cybersecurity researcher has released a tool called Modlishka designed for pen testers The tool will help the pentesters, but may also facilitating the APT Groups in phishing Modlishka Feature: Phishing tool that bypasses Gmail 2FA Support for majority of 2FA authentication schemes Support for majority of 2FA authentication schemes (by design). No website templates (just point Modlishka to the target domain - in most cases, it will be handled automatically). Full control of "cross" origin TLS traffic flow from your victims browsers (through custom new techniques). Flexible and easily configurable phishing scenarios through configuration options. Pattern based JavaScript payload injection. Striping website from all encryption and security headers (back to 90's MITM style). User credential harvesting (with context based on URL parameter passe

Introduction Mastering tips and tricks while working with Zimbra can help you maximize the platform's email features. This article compiles useful tips and tricks in a PDF format, making it easy for you to access and apply them in your daily work. Let's explore and enhance your productivity with Zimbra through the practical suggestions shared in this article. Zimbra guilde to see how to use? Blog zimbra share Top 15 Tips & Tricks - Happy new year. Sharing Tips and Tricks with Zimbra Download the guide now to see how to (with easy-to-follow steps and video demos): Search in Zimbra Import Into and Export From Zimbra Change Your Zimbra Preferences Change Your Zimbra Theme Set Zimbra Email and SMS (text) Reminders Enable Mandatory Spellcheck Sort Email Enable Two-Factor Authentication (2FA) Create an Appointment with the Mini Calendar Create an Email Alias, Distribution List or Contact Group Launch an Email in a Separate Window Turn on Zimbra’s Activity Stream

Introduction Discover the world of Linux bin bash shell in this comprehensive guide. Learn from basic to advanced examples, understand shell scripting, and explore frequently asked questions. The Linux bin bash shell is an essential component of the Linux operating system, providing users with a command-line interface to interact with the system. Whether you are a beginner looking to understand the basics or an advanced user seeking to refine your scripting skills, this guide offers a detailed exploration of the bin bash shell. What is the Linux Bin Bash Shell? Understanding the Shell The shell in Linux is a command-line interpreter that executes user commands. The term "bash" stands for Bourne Again Shell, an enhanced version of the original Unix shell created by Steve Bourne. It is the most popular shell in Linux, with its executable located at /bin/bash . Why Use Bash? Versatility : Bash is widely used for its simplicity and power. Scripting : Automate tasks through shell

Introduction While using Zimbra Zimbra , you might encounter the "Client host rejected: Access denied" error, which can disrupt your workflow. This is a common issue that can be resolved easily if you understand the causes and the solutions. This article provides a detailed guide on how to fix this error on Zimbra, helping you quickly resume your work smoothly. Zimbra client host rejected Access denied error log Dec 19 01:21:28 mail postfix/amavisd/smtpd[5106]: NOQUEUE: reject: CONNECT from unknown[192.168.1.113]: 554 5.7.1 <unknown[192.168.1.113]>: Client host rejected: Access denied; proto=SMTP Dec 19 01:21:28 mail postfix/amavisd/smtpd[5106]: lost connection after CONNECT from unknown[192.168.1.113] Dec 19 01:21:28 mail postfix/amavisd/smtpd[5106]: disconnect from unknown[192.168.1.113] Allow the network " 192.168.1.0/24 " of client host for zimbraMtaMyNetworks attribute [zimbra@mail ~]$ zmprov ms `zmhostname` zimbraMtaMyNetworks "127.0.0.0/