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Cloud on Willem's Blog

Backup Rotation Scheme

Rotate your backups with 'rsync-backup-rotator'

Dec. 15, 2023
Learn about the rsync-backup-rotator tool that helps you automatically rotate backups using rsync, creating and maintaining multiple recovery points from your backups.

In today's digital age, safeguarding your data is paramount. Simply creating a copy of your files may not be enough as they can get corrupted, overwritten or blocked by ransomware. Having multiple, time-rotated (and ideally, offsite) backups is a stronger defense. I created a new tool, rsync-backup-rotator, to help you with this.

Using AI to generate code

Programming with super powers

May 3, 2023
Discover how AI-generated code can revolutionise your software development process and optimise cloud performance in our fascinating exploration of GPT-4's transformative capabilities.

As part of my software optimisation efforts to cut cloud costs, I needed to replace an existing piece of inefficient server software with something that uses more robust (yet fragmented) tooling available in Debian GNU/Linux. Could the GPT4 language model deliver me some AI magic? Read along!

Working Offline First

Learning from a 15-year old ThinkPad X200

May 1, 2023
Dive into a digital blast from the past and learn how a 15-year-old ThinkPad X200 can revolutionise your workflow – join my cloud-free adventure today!

As part of a greater plan to optimise my entire workflow, I am doing a little experiment this month: using a 15-year old ThinkPad X200 laptop as main computer. It’s from an era before “the cloud”, popular among free/libre software enthusiasts. What can we learn from this antithesis of modernity?

Cutting Cloud Costs

The Significance of Software Optimisation

Apr. 5, 2023
Facing sky-high cloud costs, I found software optimisation vital. Discover how I saved 90% on cloud expenses!

Like many, I faced soaring cloud service costs for my clients, prompting a wake-up call. To stay afloat, it's essential to incorporate software optimisation as a strategy for managing cloud expenses. Join me as I share how I managed to save up to 90% on cloud costs through optimisation!

CAPTCHA Alternative

Protect your forms in a user friendly way

July 30, 2022
If you're looking for a user-friendly alternative for CAPTCHA's you should check this post out where I outline how I protect web forms against malicious actors and spammers.

Chances are that you've encountered a CAPTCHA in the wild: they protect web forms by asking you to type over weirdly rendered characters or by asking you to select photos containing a particular thing. Why are they used and is there a user friendly alternative?

Using Google Free Android

Volla Phone as alternative to mainstream Android and iOS

Oct. 25, 2021
Using a Google Free Android phone is uncommon these days, yet I decided to try the Volla Phone to experience its freedom and privacy.

Nearly all folks I know use iOS or Android from a mainstream smartphone brand, yet alternatives still exist! The German Volla Phone prides itself to be a worthy option for those who value privacy and freedom. I bought one to experience it firsthand, read along for my thoughts!

Protecting VMware ESXi

Improve security using a firewall and proxy server

Aug. 31, 2021
In response to a possible security breach on a VMware ESXi host machine, I search for a way to improve security of the management console using NGINX and a firewall

In response to an incident on a server, I detected a possible security breach. The affected machine ran VMware ESXi, a bare metal hypervisor used to run virtual private servers. In standalone mode, a web based management console offers full control over the infrastructure, posing a risk.

Migrating to the Cloud

Clearing an on-premise server room

June 30, 2021
Helping a customer clear its on-premise data room and migrate to the cloud: an adventure full of cables, cabinets and bandwidth!

For a Dutch organisation that serves customers throughout Europe, I was asked to help dismantle a live server room. Instead of simply pulling the plugs, some of the services had to be migrated to the cloud. For fun and inspiration I share three different strategies to do so.

The value of notifications

How to setup your smartphone to save time

Feb. 22, 2021
It's easy to dismiss your phone's notifications as something that disturbs you, but if you take the time to set them up correctly, notifications can actually save you time!

It's easy to dismiss your phone's notifications as something that disturbs you, something annoying. But if you take the time to set them up correctly, notifications can actually save you time in the long run. Gain more focus by taking control over your online connection to the world. Read along for some tips!

Realtime service uptime monitoring

Discover problems before your customers do

Feb. 2, 2021
Downtime happens and it is nothing to be ashamed of, just make sure that you set yourself up to discover problems as soon as possible! Know about problems before your customers do!

Downtime happens and it is nothing to be ashamed of, just make sure that you set yourself up to discover problems as soon as possible! You can use realtime uptime monitoring to automatically keep an eye on your servers and services. Read along to find out how.

Building a product platform

Designing for reusability, flexibility and extensibility

Jan. 31, 2021
Leverage platform capabilities to quickly launch new products, designing for reusability, flexibility and extensibility.

This month I am leveraging platform capabilities to launch a new product. Over the years I have developed the "Lemmid" platform, a set of building blocks that allow me to swiftly develop new products. Designing a platform takes some extra considerations, but if you follow some simple rules you can do it yourself!

Increase traffic to your blog with a RSS feed

How to setup RSS/Atom using NodeJS

Oct. 31, 2020
Using NodeJS I added RSS feeds to my blog as support for feeds can still provide you with value. Read about the

Writing for my blog has been a lot of fun, I receive messages from all of the world about the things I like. Traffic is growing, every month more readers are finding their way to my blog. This week I received a request to support RSS feeds on my blog. I wondered, are RSS feeds still relevant today?

Syncing files seamlessly between smartphone and tablet

Using unison to automatically sync between GNU/Linux and the iPhone

Sep. 16, 2020
In order to optimise my workflow, I was looking for a way to seamlessly access the same files on both my computer and smartphone. Read along to find out how I did it.

In order to optimise my workflow, I was looking for a way to seamlessly access the same files on both my computer and smartphone. This is useful to when you want to quickly send files from your computer using your smartphone through various messaging apps and vice versa. Read along to find out how I did it.

Scalable application design without magic

Leveraging client computing power for high performance with many users

May 11, 2020
I needed to design a scalable backend infrastructure that could handle lots of concurrent users. I did this by leveraging the client's computing power having it handle most of the user interaction workload.

As part of the online food ordering app I'm building, I needed to design a scalable backend infrastructure that could handle lots of concurrent users. Scalability is considered a hard problem to tackle. Often it's presented like it's something magical, done by million dollar companies using secret tools. But, there is no such thing as magic, or is there?

Traffic shaping using iptables and tc

Limiting outbound network bandwidth per client IP-address

Apr. 1, 2020
This month I responded to an automated alert indicating excessive bandwidth usage on a server, requiring me to apply traffic shaping to mitigate the traffic.

Last month I received an automated alert indicating excessive bandwidth usage, usually a sign of trouble. When this happens, you should follow a standard incident procedure, trying to isolate the source of the traffic before shutting it down. The cause of this incident was not what I expected however... requiring a different kind of mitigation than a simple blockade.

Monolithic vs Microservices software architecture

Choosing the right design for your app development

Mar. 3, 2020
This week I flew to Gothenburg to talk about enterprise software architecture, read along to learn about choosing the right architecture for your app development

This week I flew to Gothenburg to meet people from a large international shipping company, talking about the development of enterprise level software. During the meeting there were various experts in the room, one of them asked me on choosing the right software architecture (for big, complex, enterprise level apps). A very good question, well worthy for a blog post.

Your own addressbook and calendar cloud

Share contacts, agendas and tasks with CardDAV/CalDAV

Feb. 28, 2020
You can setup a CardDAV/CalDAV server to manage your own contacts, addressbook, agenda and task data and share it between your devices.

If you use different devices and computers to get things done, you might want to synchronise contacts, agendas and tasks. You can use any of the 'big cloud' services for this, like Apple iCloud, Microsoft Office 365 and Google Gmail. But, if you prefer not to share your addressbook and calendar with big American companies, you can do it yourself.

Building a professional 72TB NAS

Configuration and installation of an HPE ProLiant DL380 server

Nov. 22, 2019
This month I installed a professional HPE ProLiant DL380p server in a datacenter in Amsterdam, read this post to see how this was done!

Over the past few years I have been moving my data and work from local computers (mostly laptops) into the cloud. Cloud computing is done by servers in a datacenter, powerful computers that do the hard work. As my company grew, I needed more capacity. It was time to add some power to my cloud!

Fighting backscatter spam at server level

Configure Postfix to block spam before it enters the server

Sep. 10, 2019
Deal with backscatter spam by implementing a stringent SMTP delivery policy at MTA level.

This month I had to deal with backscatter spam, affecting one of the mail servers I manage. As server engineer I make sure that servers don't send spam and that incoming email gets filtered. Despite all good efforts, this server kept being blacklisted for sending spam to iCloud, Office 365 and Google Gmail for Business (G Suite). Read along to find out how what caused this and how to fix this.

Dig for dummies

Explaining an highly useful network tool

May 24, 2019
Learn how to use the dig command to query domain name servers to find the source of network problems, IP-addresses, hostnames, mail servers and related info.

When you're building websites, apps or email services you may run into domain names and their configurations. When everything is working as it should, most of this is invisible. But when troubleshooting a domain name configuration, it may be necessary to dig a little deeper... read along to learn how!

Search like a pro: Google search operators

Comprehensive list of advanced search operators

Apr. 25, 2019
Read along for a comprehensive list of advanced Google search operators that allow you to filter your search results.

You probably use the world's most famous search engine to find things everyday, but you might not know about some of its advanced search operators. You can use these special search phrases to find things that are otherwise burried in the search results. Read along for a comprehensive list of advanced Google search operators.

WordPress: 10 tips to secure your website

Keep hackers out of the world's most popular content management system

Mar. 31, 2019
A lot of people use WordPress to manage their website. Prevent your site from being hacked using this blog post.

A lot of people use WordPress to manage their website, therefore it's no surprise people ask me to have a look at their site's security. As ethical hacker, I encounter WordPress in different shapes, sizes and states. Some of them are really badly protected against hacks. Prevent your site from being hacked using these 10 practical tips.

Understanding the security concerns in shared hosting

Considering open ports and unused network facing services

Feb. 28, 2019
People pay me to hack them, provided I'll explain how I did it. Read along to learn how hackers use security holes to hack your app, webshop or website!

People pay me to hack them, provided I'll explain how it was done, so future hacks can be prevented. As security consultant, I scan for weaknesses in my clients' apps, webshops and websites. Very often a hack starts by exploiting a security hole that is visible remotely. Read along to learn how hackers find security holes and what you can do to secure them.

Is the Apple Watch the modern tool watch?

Testing the Apple Watch's usefulness in real life

Nov. 2, 2018
I tested the Apple Watch during my work in Frankfurt this week where I had to go inside an internet data centre.

This week I went to Frankfurt for business. I had to perform maintenance to servers in a data centre. This seemed like a great opportunity to test the Apple Watch's usefulness in real life (other than health and fitness). I wondered, is the Apple Watch the modern tool watch?

Optimising images for the web and performance

Reduce filesize with jpegoptim, optipng, pngcrush and pngquant

Sep. 26, 2018
Make your website faster by optimising the images. This posts explains how you can do this.

One way to make your website faster is to make it smaller. Not with tiny fonts, but with less bytes! More than half the weight of an average website is because of images. Yet very few people optimise their images for the web and performance, time to find out how much bytes you can safe!

Google Analytics vs AWStats

Understanding web traffic statistics software

Aug. 20, 2018
Comparing Google Analytics with AWStats to find out where they differ and which is better.

This month I have been working on website statistics, tracking traffic using different technologies. Some of my customers use Google Analytics, others use AWStats, and some use both. Which is better is often debated, but few people really understand the differences. Time to shed some light on the magic of web statistics.

Cyber security: 5 easy tips to protect your server against hackers

Server hardening best practices for Windows and Linux

Mar. 10, 2018
These 5 practical cyber security measures will improve the safety of server, website and data.

This week one of my clients was hacked and asked me for emergency assistance to help secure their server infrastructure. It was a web server that ran WordPress websites on Apache (with PHP/MySQL), including a few webshops with customer data. This hack could easily have been prevented with the following best practices, is your server secure?

Tablet as main computer

Comparing the Microsoft Surface Pro to iPad Pro

Mar. 7, 2018
I have been using a tablet as my main computer for quite some time now. In this blog post I share you my experience on using Surface Pro and iPad Pro to get my work done.

For the past few weeks I have been using the Microsoft Surface Pro as my main computer. It's a modern tablet computer that can be used as laptop with the type cover. With the Surface Pen, it's a versatile PC that works in a lot of different ways. Time to find out if it's any good and how it compares to my other tablet computer, iPad Pro.

Clouds below my floor

Building a little datacenter in my basement

Aug. 31, 2017
Building a little datacenter in my basement utilising a very fast internet connection.

At my home I have this crazy fast optical internet connection. It is a 600MB up and down fibre connection which directly arrives in my home (no copper cables involved). It's like a private internet highway. Reason enough to find out if I could do something to make better use of all this speedy fiber galore...

The day I killed my LAN

Turned off my local network and went 4G only

July 31, 2017
I killed my office LAN and went 4G only. Saves a lot of clutter, energy and money.

Today I called my provider to quit my office's ADSL internet subscription, I don't need it anymore. I have turned off my local area network and switched my workflow onto mobile internet only. The simplicity and savings actually surprised me so much, that I made blog post for it.

iPad Pro next to my primary machine

Using it with Apple Pencil as a creative powerhouse

Jan. 30, 2017
Using iPad Pro with Apple Pencil next to my computer to form a create powerhouse

I wanted see if I can find something better than my old fashioned pencil and paper that I use for designing software as professional developer. I knew iPad Pro from my test last summer, figuring out if it could replace my primary development machine. While it may not be able to completely replace my thrustworthy ThinkPad, it turned out to be a totally different story when it comes to paper.

iPad Pro as primary computer

testing iOS as primairy development platform

Aug. 15, 2016
Is the time right to use an iPad as primary development platform to get some real work done?

The lack of physical clutter, distracting branding, or blinking LED's makes the iPad Pro a textbook example of minimal design. My despiction of distraction explains my interest in using the iPad Pro as only computer to test if it is up to the task. Is Apple's latest effort on iOS enough to enable it to do serious development work?

Building the blog... in style!

Developing on a 20-year old computer with 16MB RAM and Windows 98

June 23, 2016
Find out if it is possible to turn a computer from the 90s into a modern development machine.

One must be a bit crazy to come up with the idea to build a blog (as in: actual programming) on an old 486 laptop with just 16MB RAM. I happen to be that crazy: I took my very first laptop from the 90s and decided to find out if it was possible to turn it into a development machine.

All blog posts
A map of the ARPANET in 1973... imaging mapping the internet today!  (Public domain)
A map of the ARPANET in 1973... imaging mapping the internet today! (Public domain)
Prevent backscatter bounce messages by responding with SMTP error codes instead
Prevent backscatter bounce messages by responding with SMTP error codes instead
Apple Watch - a modern tool watch?
Apple Watch - a modern tool watch?
Different kinds of hosting: Shared hosting, VPS hosting and dedicated hosting visualised (a circle representing a physical server)
Different kinds of hosting: Shared hosting, VPS hosting and dedicated hosting visualised (a circle representing a physical server)
Limit access by IP basis to XML-RPC using a .htaccess file
Limit access by IP basis to XML-RPC using a .htaccess file
Once a hacker knows what software your website uses, its easy to lookup known security holes using databases like cvedetails.com
Once a hacker knows what software your website uses, its easy to lookup known security holes using databases like cvedetails.com
Using dig to get information about a domain name, willem.com
Using dig to get information about a domain name, willem.com
Do you trust the free wifi you're using? (Image via buffered.com)
Do you trust the free wifi you're using? (Image via buffered.com)
The world on your wrist - using Apple Maps in downtown Frankfurt
The world on your wrist - using Apple Maps in downtown Frankfurt
Google Analytics and AWStats - web traffic statistics software
Google Analytics and AWStats - web traffic statistics software
Simple backscatter scenario, mail server bounces message to a falsified sender address
Simple backscatter scenario, mail server bounces message to a falsified sender address
The data centre is where your server lives. Even though it may be physically secure, you should check upon its software too!
The data centre is where your server lives. Even though it may be physically secure, you should check upon its software too!
Typical piece of Google Analtyics JavaScript code - you can clearly see it referring to Google's servers
Typical piece of Google Analtyics JavaScript code - you can clearly see it referring to Google's servers
Time and date can be checked easily using Apple Watch
Time and date can be checked easily using Apple Watch
Accessing information while keeping my hands free
Accessing information while keeping my hands free
Average web page weight, divided by asset type (HttpArchive, September 2018)
Average web page weight, divided by asset type (HttpArchive, September 2018)
Robots surfing the web: bot traffic listed by AWStats
Robots surfing the web: bot traffic listed by AWStats
Microsoft Surface family
Microsoft Surface family

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