In this comic, the concept of an ordinary person having an FTP server is quickly dismissed. And yes, it’s not common. To the average computer user, the idea that someone could just… connect to your computer feels exotic, or even dangerous — see the very common ironic fear of your IP address being known to other people on the internet.
If you take someone who’s “good with computers” but not a networking person, their mental model of The Internet probably involves a definition of “servers” or “the cloud” that distinguishes them from personal computers in some meaningful way. True peer‐to‐peer, if they ever think about it, is an endeavor: WebRTC, STUN, TURN, ICE, what have you. Given that we live in a world of NAT, CGNAT, and restrictive ISPs, this isn’t entirely wrong, but it breaks the elegant design of the original Internet. //
There’s lots of things you can blame for killing the open Internet, but I think NAT was one of the earliest. Running a server used to be trivial: run an executable, tell people your address, done. Now, if you’re lucky, you probably have to configure port forwarding, which you often can’t even do if you’re behind CGNAT or on an institutional network.
It also trained everyone to think client‐server is natural. “My device talks to The Cloud which talks to other devices” feels normal, when that feeling originated as an artifact of address scarcity. The problem the people in the XKCD comic at the top are facing is the absurdity of trying to establish a one-to-one communication using only outbound connections on both sides. Even more ironic is that NAT got normalized as a security feature — “your devices are hidden!” — which is one of the things that made people resist the thing that would fix it.
NAT certainly isn’t the only reason why the modern internet is full of centralized walled gardens, but it was the first — it’s why it’s hard to send a file to someone, it’s why you don’t run your email on your own computer, and why running your own services at all is difficult and often expensive (if you can’t port forward from your own internet connection, you have to buy a VPS instead of using hardware you already have).
