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 FOSS in a detailed and easy-to-understand manner, ensuring your email accounts are better protected against potential threats. In today’s digital landscape, securing your email accounts is paramount. Zimbra FOSS (Free and Open Source Software) provides a powerful email platform, widely adopted for its flexibility and reliability. To strengthen its security, integrating two-factor authentication (2FA) is a must. This guide will walk you through the step-by-step process of enabling Zimbra FOSS 2FA, ensuring that your email platform is robust against unauthorized access. Why Use Two-Factor Authentication with Zimbra FOSS? Two-factor authentication adds an extra layer of security by requiring u...

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)$ { ...

Introduction In the world of cybersecurity, reverse proxies are essential for a variety of applications, from load balancing to security testing. One such tool that has caught the attention of professionals is Modlishka . In this article, we’ll explore the features, benefits, and best practices for using Modlishka while maintaining ethical standards in cybersecurity. What is Modlishka? Modlishka is a cutting-edge reverse proxy tool designed to facilitate advanced security testing and penetration testing. Unlike traditional reverse proxies, Modlishka can seamlessly forward web requests while maintaining full control over data transmitted between the client and the target server. This ability makes it especially useful for testing login credentials, bypassing security filters, and conducting social engineering attacks in a controlled and ethical environment. Key Features of Modlishka Impersonation Capabilities : Modlishka can act as a middleman between the target and the user, allowing a...

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 Collaboration Suite is a powerful, open-source email and collaboration platform designed for businesses and organizations. It offers robust email, calendar, contact management, and file-sharing capabilities, making it a favorite among IT professionals. This guide delves into sharing tips and tricks with Zimbra, providing a step-by-step exploration of essential techniques and tools to boost productivity and collaboration. Understanding Zimbra’s Sharing Features What is Zimbra Sharing? Zimbra Sharing allows users to collaborate by granting access to their email folders, calendars, tasks, or address books. With customi...

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 , 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 "127.0.0.0/8 192.1...

Introduction Zimbra is a popular open-source email server solution used by many organizations worldwide. However, like any software, it can encounter issues that disrupt its functionality. One such common issue is the " Zimbra ERROR zclient IO ERROR."  This error can cause significant disruptions in email services, impacting communication and productivity. In this comprehensive guide, we'll explore the causes of this error and provide solutions ranging from basic troubleshooting to advanced fixes. Understanding the Zimbra ERROR zclient IO ERROR What is the Zimbra ERROR zclient IO ERROR? The "Zimbra ERROR zclient IO ERROR" is a connectivity issue between the Zimbra client and the server. This error typically indicates problems with network connections, server configurations, or client settings that prevent successful communication. Common Symptoms Inability to send or receive emails Frequent disconnections from the email server Error messages indicating IO issue...