About haasje.net

Hi, I am Jelle. I work in network and security engineering, which means I spend a lot of time with firewalls, certificates and the sort of problems that start with "it works from my laptop, but not from there".

This site is where I keep the small things I build and the explanations I end up writing down anyway.

What you will find here

• whatsmyip.haasje.net: a fast IPv4/IPv6 lookup that also answers plain text to curl and wget.
• Guides: practical explainers on IP addressing and related networking basics.

How the site is funded

The guides can show Google AdSense ads. They are placed between sections, labelled as advertisements, and never cover the content. I do not accept paid reviews or sponsored posts, and the ads have no influence on what I write.

Corrections

I try to keep everything accurate, but networking has many corner cases. If you spot a mistake, please tell me and I will fix it.