UFW (uncomplicated firewall) is a firewall configuration tool that runs on top of iptables, included by default within Ubuntu distributions. It provides a streamlined interface for configuring common firewall use case...

This guide provides a quick reference to OpenSSL commands that are useful in common, everyday scenarios. Similar to a cheat sheet for OpenSSL commands.

This guide focuses on identifying and troubleshooting the most commonly encountered HTTP error codes, i.e. 4xx and 5xx status codes, from a system administrator's perspective. There are many situations that could caus...

OAuth 2 is an authorization framework that enables applications to obtain limited access to user accounts on an HTTP service, such as Facebook, GitHub, and DigitalOcean. It works by delegating user authentication to t...

Terraform is a tool for building and managing infrastructure in an organized way. In this tutorial, you'll install and use Terraform to create an infrastructure on DigitalOcean that consists of two Nginx servers that ...

Iptables is a software firewall for Linux distributions. This cheat sheet-style guide provides a quick reference to iptables commands that will create firewall rules that are useful in common, everyday scenarios. This...

Iptables is a firewall technology that plays an essential role in network security for many Linux systems. In this tutorial, we will cover how to do the following iptables tasks: list rules, clear packet and byte coun...

In this guide, we'll get a LEMP stack installed on an CentOS 7 server. A LEMP software stack is a group of open source software that is typically installed together to enable a server to host dynamic websites and web ...

In this tutorial, we will go over how to use tinc to create a secure VPN on which your servers can communicate as if they were on a local network. We will also demonstrate how to use tinc to set up a secure tunnel int...

PostgreSQL, or Postgres, is a relational database management system that provides an implementation of the SQL querying language. It is a popular choice for many small and large projects and has the advantage of bein...

In this tutorial, we will cover setting up a production-ready Node.js environment that is composed of two CentOS 7 servers; one server will run Node.js applications managed by PM2, while the other will provide users w...

A PostgreSQL database is a robust and flexible choice for your Ruby on Rails application. In this tutorial, you will set up a Ruby on Rails development environment connected to a PostgreSQL database on an Ubuntu 18.04...

A FAMP stack, which is similar to a LAMP stack on Linux, is a group of open source software that is typically installed together to enable a FreeBSD server to host dynamic websites and web apps. FAMP is an acronym tha...

An important part of managing server configuration and infrastructure includes maintaining an easy way to look up network interfaces and IP addresses by name, by setting up a proper Domain Name System (DNS). Using ful...

This tutorial will show you how to install Java on CentOS 7 (also 5, 6, 6.5), Fedora 20, and RHEL. Java is a popular software platform that allows you to run Java applications and applets. The installation of the fol...

This tutorial is an ELK Stack (Elasticsearch, Logstash, Kibana) troubleshooting guide. It is structured as a series of common issues, and potential solutions to these issues, along with steps to help you verify that t...

IP Geolocation, the process used to determine the physical location of an IP address, can be leveraged for a variety of purposes, such as content personalization and traffic analysis. In this tutorial, we will show yo...

In this tutorial, we will go over the installation of the Elasticsearch ELK Stack on Ubuntu 14.04—that is, Elasticsearch 2.2.x, Logstash 2.2.x, and Kibana 4.4.x. We will also show you how to configure it to gather and...

In this tutorial, we will show you how to use Let's Encrypt to obtain a free SSL certificate and use it with Nginx on Ubuntu 16.04. We will also show you how to automatically renew your SSL certificate. If you're runn...