Cyber Defence

rmmod Command in Linux: Remove Kernel Modules and Blacklisting

The rmmod command in Linux removes a loaded module from the running kernel. Because the kernel has a modular design, you can…

2 weeks ago

free Command in Linux: Check Memory Usage and Interpret Output

The free command in Linux gives you a quick summary of RAM and swap usage. It reads from /proc/meminfo and displays the data in…

2 weeks ago

diff Command in Linux: Compare Files and Create Patches

The diff command in Linux compares two text files line by line and shows the lines that differ. When files are identical,…

2 weeks ago

Flush DNS Cache on Windows, Linux, and macOS: Quick Commands

DNS cache is a temporary database your OS and browser build as you browse. Each time you visit a website, the domain-to-IP mapping is saved locally, cutting out the round trip to a remote DNS server on repeat visits. Stale entries are the most common reason to flush the DNS cache: a server moves to a new IP, but your OS or browser still routes to the old address. This guide covers how to clear the DNS cache on Windows, Linux, and macOS, and how to flush the separate cache stored inside Chrome and Firefox. Flush DNS Cache on Windows The command is the same on Windows 10, Windows 11, and earlier supported releases. Open Command Prompt with administrator privileges. Type cmd in the Windows search bar, right-click Command Prompt, and select Run as administrator. Run the flush command: bashipconfig /flushdns A successful run prints:…

2 weeks ago

Change User Password in Ubuntu: Command Line and GNOME GUI

Using a strong, unique password for every account is one of the most effective security habits. A compromised password accounts…

2 weeks ago

Enable and Disable the Root Account in Ubuntu: Full Guide

Ubuntu locks the root account by default. New users often wonder what the root password is or how to log…

2 weeks ago

Configure Netplan on Ubuntu: DHCP, Static IP, Wi-Fi, and Bridges

Since Ubuntu 17.10, networking is configured with Netplan rather than the older /etc/network/interfaces file. You write a short YAML description of how…

2 weeks ago

Install Docker on Ubuntu 24.04: Repository, Compose, and Non-Root

Docker is an open-source containerization platform that packages an application and everything it depends on into a single container. That…

2 weeks ago

update-alternatives on Ubuntu: Manage Default Program Links

When two or more installed programs provide the same command name, the system needs a way to decide which one…

2 weeks ago

Install Docker on Ubuntu 26.04: Official Repository Setup Guide

Install Docker on Ubuntu 26.04: Official Repository Setup GuideDocker is an open-source container platform that packages application code together with…

2 weeks ago