A curl in every port

Excellent article! Thank you!

Love the stories behind things we take for granted.

💡 Before HTTP was assigned TCP port 80, it ran on port 2784 as those were the last four digits of Sir @timberners_lee his parents’ phone number. /via @adactio — adactio.com/journal/16531

💡 Before HTTP was assigned TCP port 80, it ran on port 2784. The number was chosen by Sir @timberners_lee himself as he could easily remember it: they were the last four digits of his parents’ phone number. /via @adactio — adactio.com/journal/16531

One of the easter eggs we accrued whilst our hacking session at CERN last year: adactio.com/journal/16531

A curl in every port adactio.com/journal/16531

As I go through my daily work in web dev, I constantly have questions bouncing around in my head that are too low of a priority to really research. But, when they bounce around in my head long enough, my curiosity won’t let me sit idly by.

One such bouncing question deals with port numbers. It seems like every time I run npm start on a web project, it’s a roll of the dice as to which port of localhost I’ll get a local dev server on.

I understand perfect uniformity across all projects is unlikely (not everyone will be on port 8000), but it’s also not completely random across the entire spectrum of thousands of ports (I never get a local dev server on 4971 or 9571 or 6373).

Why does the local dev server port always seem to be a random selection between about four to five ports?

I asked on Twitter:

Does somebody have an article like “A short history of port numbers” that describes why I never get a consistent default port experience across tools? Some commons ones I consistently see:

localhostlocalhost:3000localhost:8000localhost:8080localhost:8888

And further:

why/where did those numbers pop into our collective culture? why not 2000 or 4000? or why not 6666? or any other random number for that matter?

To be clear, this post is not meant to be the definitive answer to that question. But I read enough random links on the internet to arrive at what feels like a satisfactory answer (though I can’t vouch for the accuracy of it).

So I will try re-stating what I found across various resources on the web and see if I can weave them all into a coherent narrative.

Ports 80

Ports 30

So what about port 3000? That doesn’t even have an eight in it anywhere. Where did that number come from?

I’m personally aware of the prevelance of port 3000 because of its ubiquity in the Node ecosystem. But from what I gather, Ruby (which predates Node) also uses 3000 prevalently (and, as you probably guessed, malware uses it too). Ultimately, I cannot find a story behind that port.[2]

That said, once a project like Node does something you can imagine how it spreads: for whatever reason, somebody starts using port 3000 in code or docs or examples, and that spreads to become the standard port for starting an HTTP server in Node. From there the number spread like wildfire into the community and tooling (which would explain why the first place I remember seeing port 3000 used in a dev server was when I first used create-react-app).

Conclusion

Phew. I think I have sufficiently answered my own question to a degree of satisfaction where my curiosity will let me rest.

Some additional links from my research:

• “What’s the story behind port 8080?” on Quora
• “Why is port 3000 used when running a Node.js application?” on Quora
• “List of TCP and UDP port numbers” on Wikipedia
• “Registered port” on Wikipedia
• “Priviliged ports” on w3.org
• “Service Name and Transport Protocol Port Number Registry” on iana.org
• “Port 8080” in the Port Authority Database (from the Gibson Research Corporation)
• “The History of the URL” on The Cloudflare Blog

1. IANA is responsible for resources related to internet protocols and it appears you can register (i.e. reserve) commonly used port numbers for well-known services. For example, 8008, 8080, and 591 are all considered HTTP alternatives, a.k.a. http-alt. 591 seems like a random outlier, but it appears to be because FileMaker chose to use it as an alternative port (and registered it as one). ↩
2. Port 3000 is registered with IANA for “RemoteWare Client” and “HBCI”. If you Google those names with the people who registered them, the furthest convo back I can find is an obscure mailing list text that sheds no light on the subject. So who knows where 3000 came from. ↩

@adactio fascinating! thanks for sharing, definitely gonna update my post with a link back