Sysadmin

Various guides and articles about servers and products such as haProxy and nginx.

Installing required WordPress extensions for PHP 8.

A guide on how to install certain PHP 8 extensions for WordPress.

How to stop Fail2ban from causing high CPU usage.

A tutorial on how to stop Fail2ban from going haywire and hogging your server’s CPU.

How to test your HAProxy configuration file.

A quick guide on how to validate your HAProxy config file before you attempt to restart it.

Nginx: SSL_do_handshake() failed… and that’s OK!

The SSL_do_handshake() failed error is nothing to worry about in most cases.

MySQL: Extract Year and Month from Date column.

This is a short guide on how to get the year and month from a date column in MySQL.

How to create a new Sudo User on Ubuntu.

In this guide, we are going to show you how to create a new sudo user on Ubuntu.

How to disable the Nginx access log.

This is a guide on how to disable the Nginx access log.

Test Nginx configuration file.

This is a short guide on how to test your Nginx configuration file without restarting your web server.

How to get the current PHP version.

This a guide on how to check the current version of PHP.

How to force HTTPS with Nginx.

In this guide, we will show you how to force HTTPS on an Nginx server. To do this, we will redirect all “plain” traffic to our HTTPS URLs.

MySQL: Server sent charset (255) unknown to the client.

This issue occurs because MySQL 8 changed its default charset to utfmb4. As a result, older software might not be able to connect to it.

MyISAM locking explained.

The other day, some of our users reported that saving data had become extremely slow. In some cases, forms were taking up to 15 seconds to submit.

Preventing X-Forwarded-For spoofing in HAProxy.

This is a guide on how to prevent IP spoofing with HAProxy.

The Facebook crawler DDOS.

Facebook’s crawler is an untamed beast and if you are not careful, it will cause you a lot of problems. Especially you use a lot of story images.

Renaming a file with the Linux command line.

This is a short beginners guide on how to rename a file using the Linux command line.

Speeding up HAProxy SSL with multiple CPU processes.

This is a guide on how to speed up SSL on HAProxy. In this post, I will show you how to dedicate specific CPU processes to HTTP and HTTPS traffic.

Blocking POST, TRACE and PUT requests with HAProxy.

A short guide on how to allow or deny certain HTTP methods using HAProxy.

Prevent unwanted domains from forwarding to Nginx.

A short guide on how to prevent spammy domains from forwarding to your Nginx web server.

PHP-FPM settings tutorial. max_servers, min_servers, etc.

A guide on selecting the correct www.conf settings for PHP-FPM.

Guide: Upgrading HAProxy from 1.6 to 1.8 on Ubuntu 16.04.4 LTS (Xenial).

This post details the steps that I took to upgrade HAProxy from 1.6 to 1.8 on Ubuntu 16.04.4 LTS (Xenial).

ngx_slab_alloc() failed: no memory in SSL session shared cache “le_nginx_SSL”

An SSL issue that I ran into the other day.

Incorrect validation certificate for tls-sni-01 challenge.

The other day, I came across a frustrating issue while attempting to renew the Let’s Encrypt SSL certificate on my haproxy load balancer.

Fixing “Uncaught error: Call to undefined function curl_init”

This is a common error that occurs whenever PHP’s curl extension has not been installed or enabled.

Linux: Delete files older than 30 days.

This is a short guide on how to use the Linux find utility to remove old files.

MySQL: INT(11) vs TINYINT(1) – What do the numbers in brackets mean?

When it comes to columns such as INT (11) and TINYINT (3), the number in brackets isn’t actually that important.

Force HTTPS with HAProxy.

This is a short tutorial on how to force HTTPS / SSL with the HAProxy load balancer.

SSL with HAProxy and PHP: Forwarding HTTPS header.

A short guide on how to forward HTTPS headers with HAProxy so that PHP knows what protocol is being used.

Setting up haproxy as a load balancer with sticky sessions.

In this tutorial, I will show you how to setup haproxy as a load balancer that uses sticky sessions.

Fix: index.php not being loaded by default.

In this article, we will show you how to solve the issue of index.php files not being served as the default file.

SQL Server: “The password of the account has expired.”

User passwords on SQL Server will expire by default. To disable this, you will need to untick the expiration checkbox.

Fixing “mvn not recognized as an internal or external command” error

I encountered this error while attempting to install Apache Maven on a Windows PC.