Skype is one of the most widely used communication platforms in the world. It lets you make free audio and video calls over the internet, send instant messages, share files, and make affordable calls to mobile and landline numbers worldwide. Microsoft...

UFW (Uncomplicated Firewall) is a user-friendly front-end for managing iptables rules on Ubuntu. It ships pre-installed and simplifies tasks that would otherwise require writing complex iptables commands by hand. UFW is the standard way to control inbound and outbound traffic on...

A properly configured firewall is one of the most important layers of security for any internet-facing server. UFW (Uncomplicated Firewall) is a user-friendly front-end for managing iptables rules that ships pre-installed on Ubuntu. Its defaults are sensible: block all incoming connections, allow all outgoing connections. No outside traffic reaches your server unless you explicitly open a port. This guide covers how to configure a UFW firewall on Ubuntu 18.04, from setting default policies and application profiles to writing allow and deny rules for specific ports, IPs, and subnets. Configure UFW Firewall on Ubuntu: Defaults, SSH, and Application Profiles If UFW is not installed, add it with: Check the current status: Application profiles. When you install a service with apt, it registers a profile in /etc/ufw/applications.d/. List all available profiles: Use a profile name or a port number interchangeably when writing rules. To see what ports a profile covers: Allow SSH before enabling UFW. This is the most critical step. If you enable UFW without an SSH rule and you are on a remote server, you lose access immediately: If your SSH daemon runs on a non-standard port, use the port number instead, for example sudo ufw allow 4422/tcp. Enable UFW: Type y at the prompt to confirm. Allow Port Ranges, Specific IPs, Subnets, and Network Interface Rules Common...

PostgreSQL (also called Postgres) is a free, open-source, object-relational database management system with a strong reputation for reliability, SQL standards compliance, and advanced feature support. It handles complex queries, JSON data, full-text search, and custom data types, making it a natural...

Redmine is one of the most popular open-source project management and issue tracking platforms. It is built on the Ruby on Rails framework and supports multiple databases. A single Redmine installation gives your team multiple project support, wikis, a full issue...