System Admin

How to Further Secure SSH With a Port-knocking Sequence on Ubuntu 18.04

Introduction Besides changing the default port for SSH, and using a key pair for authentication, port knocking can be used to further secure (or more accurately, obscure) your SSH server. It works by refusing connections to your SSH network port. This es...

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Port Forwarding and Proxying Using OpenSSH

Introduction SSH, also known as Secure Shell, can be used for much more than obtaining a remote shell. This article will demonstrate how SSH can be used for port forwarding and proxying. The only prerequisites are an OpenSSH server (installed by defaul...

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Let's Encrypt: Migrating From TLS-SNI-01

Let's Encrypt is a free service that generates certificates to secure your website. It supports generating different types of certificates, including single-domain and wildcard. In addition, it has numerous methods to authenticate your domain to generate ...

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How to Install Apache 2.4, MariaDB 10.3, and PHP 7.2 on Ubuntu 18.04

In this article, you will learn how to setup an up-to-date LAMP stack by installing the latest stable releases of Apache 2.4 and MariaDB 10.3 on Ubuntu 18.04. Note: Ubuntu 18.04 ships with PHP 7.2 already installed, so we will only need to install some n...

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Creating Snapshots With Packer

What is Packer? Packer is a server imaging tool developed by HashiCorp. Server imaging; or alternatively, immutable infrastructure; is a popular alternative to runtime configuration tools, such as Ansible or Puppet. It is based on the idea that once a se...

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How to Install Elixir and Phoenix Framework on Ubuntu 16.04

This tutorial will show you how to install Elixir and Phoenix frameworks on a Vultr Ubuntu 16.04 server instance for development purposes. Prerequisites A new Vultr Ubuntu 16.04 server instance Logged in as a non-root sudo user. Update the system: s...

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Install Lynis on Debian 8

Introduction Lynis is a free, open-source system auditing tool that is used by many system administrators to verify the integrity and harden their systems. It can be operated as a standalone binary or it can be installed to perform checks at periodic int...

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How to Adjust Process Niceness (priority) on Most Linux Distributions

In GNU/Linux systems, "niceness" is used to define the CPU priority of a process. Essentially, it is the opposite of priority. So the nicer a process is, the less priority it has and vice versa. It is useful to adjust the niceness of a process, for exampl...

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How to Install and Use CPULimit on CentOS 7

CPULimit is a Linux utility offered to limit an application's resource usage. It is useful when you want to prevent a single application from slowing down other applications; or stop an application from using an entire core or cores for an extended period...

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How to Add a CentOS 7 Sensu Client

In the guide "How to Install and Configure Sensu Monitoring on CentOS 7", you learned how to setup a Sensu server. This tutorial is the second part, where you will learn how to add a Sensu client. A Sensu client is a server that Sensu monitors. I assume ...

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