Networking

Here is a little story about resolving an issue with a web site that turned out not to be an issue with a web site :-) A client approached me and asked, if I could look into an issue they were having with their web app. Multiple users, mainly from mobile devices, were reporting 404 Not Found errors when accessing the site’s domain. Server error for some devices? 🤨 It sounded like a strange thing that the server would give a 404 for some mobile devices. I tried to reproduce the issue, but was not able to do so, neither on one of my devices (mobile or not) nor on devices from an external device farm. ...

In a recent project I needed to anonymize IP addresses in tracking data. While masking a few bits from an IP address is not so interesting, it’s a good excuse to review some of the basics of how (IPv4) IP addresses work. What’s an IP address and how does it look like? To be able to route traffic through a network (e.g. your local network or the internet), we need a way to uniquely identify devices on that network, i.e. we need addresses. ...

I recently had the problem of needing to establish a connection to a server behind a VPN that was in the same subnet as the network I was connecting from. Every call I wanted to make to the server on the remote network wouldn’t go through as it was looking for the server on the local network. To eventually reach the server, I temporarily added a route to the routing tables, telling the client it should transmit traffic to the destination ip through the interface of the VPN connection. ...

There are multiple reasons why you would want to share a VPN connection from your Mac with another device. Maybe you have to install a proprietary VPN client which does not run on your main computer or you just don’t want to run/install it there. Maybe your main computer doesn’t “comply” (i.e. you would need to install additional AV software – who wants that?). Or you simply need it for streaming video to some TV box. ...