While scrolling through the visitor’s report of my blog, I noticed visitors from a “strange” ISP: “Magistrat der Stadt Wien, Magistratsabteilung 01”, which is the IT department of the magistrate of the City of Vienna. Digging further through the logs, I found out they are a regular visitor, and so are multiple ministries, the Austrian unemployment service, and multiple other public bodies (Maybe more, but due to IP anonymization I only know about the ones that have their own subnets). So I’ve decided to give them a special greeting when visiting. I wanted it to look like this:
Preparation
Find the relevant IP ranges
There are multiple ways to do this. Since I already knew before that the City of Vienna has their own ASN, I went over to Hurricane Electric’s BGP Toolkit (after I had to look up their ASN again) to see what IP ranges they announce. For this example, at the moment those are as follows:
