Sorry.

I implemented the current NAT system in Linux. In particular, avoiding port reservation in favor of squishing more connections into one IP address, as long as the remote address allowed us to differentiate.

This, in turn, means incoming traffic from a different address is unroutable. You no longer have a public endpoint. This is "poor man's firewall", but erodes our ability to have a server the way we used to.

I was a young engineer solving a specific problem, without considering the larger picture. It wasn't the only thing, but I feel it definitely moved the internet to a client/server infrastructure and a key equality was lost.

> 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... 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.

A lot of this feels like a requiem for the days when the only people on the Internet were "high-computer-skill" type folks. Most people will gravitate to "user-friendly" solutions: Gmail and other managed email providers were popular because they didn't stop working when you shut down your computer to save electricity, when your server's hard drive crashed, when you upgraded your computer to something with a faster processor, more RAM, and a newer operating system. It was hard enough to educate laypeople about URLs and email addresses (AOL keywords, anyone?), let alone a combination of random numbers in an IP address, or convincing people to register domain names.

Yes, NAT shoved fences into a network that was all about connecting everybody. But we'd still end up with server-client cloud architectures, even if we had started with IPv6 in the beginning. ISPs would have just sold highly restrictive firewalls as part of their home-install basic boxes, and we'd still have ended up with those fences.

Calling NAT the original sin is a serious exaggeration. Carrier Grade NAT (CGNAT) is a truly evil concept that restricts the freedoms of the CGNATed users. But regular NAT is fine as long as you can control it. "No one wanting to bother with port forwarding" is largely a matter of shitty UX on the home gateway side and laziness on the side of the operator. Same with UPnP.

If anything, NAT has saved millions of wildly insecure devices running unpatched old Windows versions from getting pwned the second they connect to the open internet.

The designers of the internet made one fundamental mistake, namely applying meatspace norms to cyberspace.

In the "real world", you don't really need that much security. Your actual security comes from the fact that all the worst criminals are already locked up, most of the would-be criminals are afraid of being locked up, and if somebody does actually commit a crime, they will get locked up and won't be able to do it again for a good while. A lot of real-world security is about post-factum detection (think alarms, CCTV, panic buttons etc), because in the real world, detection and prevention are two sides of the same coin.

This only works because if a real-world crime happens, the criminal by definition is in the same location as the victim, and law enforcement cares most about the community they serve. If the criminal is across the world, as is the case in cyberspace, even if it's a friendly country, it's often "not their problem". This means internet systems need actual security, and NAT provides exactly that.

If not for NAT, we'd all need a firewall, and things would be almost if not exactly the same. In the real world, "leave things relatively open, because locks are mostly for keeping honest people honest" is a valid strategy. This strategy doesn't work on the internet.

I remember times before NAT and SSL

You could share things easily, sure, but anyone could get hacked pretty easily and very targetted.

After NAT, sharing was still easy lots of 'piracy' apps, various messengers with NAT passthrough

Both before and after you needed to be technical, you can't ask someone that doesnt know about computers to set up an FTP server, and if they did it would be a nightmare and they'd likely share their whole drive

Same goes for anything else.

Anyway, we'll get the whole non-nat with IPv6, let's see what that brings

NAT wasn't so much normalized as a security feature as it was introduced as one. The flagship NAT product of the 1990s was the Cisco PIX, a firewall. It resulted from Cisco's acquisition of the company that originated NAT.

I think its funny everyone thinks that ISPs, Device Manufacturers, and Cloud Providers are going to let your connect back directly to your "home" with IOT devices.

Absolutely not. They can charge your $9.99/mo so you can connect their craptastic app to their craptastic cloud so you can "use their app from anywhere".

One option to resolve current worrying trends is to invest in development of alternative network protocols/structure, Yggdrasil[1][2], for example.

[1] https://yggdrasil-network.github.io/

[2] https://github.com/yggdrasil-network/yggdrasil-go

I miss the old days of ICQ and just dragging a file onto the person you are sending your file and bam, done like dinner.

As a engineering all my career life focused on networking, I am so depressed that IPv6 still not fully replaced IPv4

We have dozen of RFCs and vendors gears support IPv6 as well, but it just not finished

The distinction between NTP as a protocol and the assumptions imposed by NAT is useful, especially when considering how much modern networking depends on intermediaries rather than direct connectivity.

The consequences are so much more significant than people seem to realize.

Because of NAT, hierarchy (centralized servers) is the foundational design pattern of the internet, and anyone who wants any semblance of anarchy (decentralized networks) must use a workaround that is itself hierarchical and costly. We are all interconnected, but only a wealthy few can truly speak fist.

Yeah, no.

Working around NAT was trivial for the people who actually cared about it. I was adding port forwarding rules to my parents' router at age 12. Turns out exposing a poorly-configured Windows XP box to the wider interwebs is a Really Bad Idea - and for the same reason UPnP letting random unpatched shady P2P applications do the same is Very Much Not Good.

Let's face it: consumer devices simply aren't secured well enough to let the entire internet poke around in them, and it was even worse a decade or two ago. Decentralization is pointless when it only results in people compromising their own machines, and the people with the skills to set up a 24/7 Linux server in a broom closet won't care about adding some NAT forwarding rules.

Even without NAT, we would've definitely gotten home internet routers firewalled with a default-deny policy on all incoming connections. Exactly the same "manually configure a bypass, or use UPnP" dance blocking you from trivially running a web-available service on your machine, but with a firewall rule rather than a NAT port forward.

It's of course a different story with CGNAT, but that only became a thing well after the internet was already centralized.

NATs are also firewalls. I think people forget that before NATs, when you would install Windows, the minute you connected it to the internet, you had to rush to update it before a virus would infect it. The OS of the 90s weren't secure enough to be exposed to the WAN.

Sending files to another would be easy if only the services that allow doing this - over WebRTC - didn’t sell out to sketchy advertisers constantly. I have to look up which service is still good to use every time.

> Why you don’t have a FTP server

May be due to US DoD holding large amounts of IPv4 for no reason

Time to set up IPV6.

NAT made distinction between PCs and servers too broad.

People have forgotten, or weren't alive, but NAT was created and deployed originally by users. The problem they were solving wasn't "how do we stop running out of addresses" but rather "how do we save money". That's because early ISPs had hit on the idea of charging more for more address space, as a way to differentiate between small and large customers. So you could buy a cheaper service with one IP and use NAT to get your whole organization online.

Reading the comments:

Why do so many people still think NAT equals firewall when they're not directly related?

I guess it's because they're normally packaged together for practical reasons. They're both packet handling functions often performed in the same place. But they are NOT the same and you can have either one without the other. Most IPv6 networks have firewalls, and it's possible to have NAT that liberally passes anything.

I wonder how much this misconception has delayed V6 adoption? "But I'll be wide open without NAT!" No, you can have a firewall. Most IPv6 routers have stateful firewalls on by default.

Author is right about everything. Also: IPv6 doesn't fix this, it just introduces a new problem. IPv6 machines end up with local firewalls + stateful firewalls on the router. That router doesn't let in inbound cons. There is a part of UPnP that lets you add "pin holes" (it works like you expect) -- but the drawbacks are its kind of obscure, poorly implemented, and not guaranteed to be enabled.

The idea of router sounds simple and like it should implement some standard protocols. But in practice -- a lot of it is a mishmash of proprietary, ad hoc shitware. Something I never hear spoken about is the deep packet inspection filter component of the router firmware. It's a part of the router that decides on what traffic is allowed / not, and almost no company publishes this part. So you're not even in control of your own Internet traffic, tiny blobs of code written by some company get to decide if something is allowed or not.

If that sounds sus AF and kind of a bad idea -- well, it is. You can always run 100% open software with open-wrt. But the thing is -- the Internet isn't just your part of it. It's a network of networks, and all those shitty routers, with all that shitty firmware, is deeply ingrained within the entire Internet. That's millions of devices that would need to be replaced to fix the issue.

Related comment from another thread

https://news.ycombinator.com/item?id=49454785

> 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.

That tracks. I briefly looked into the Tailscale website and I thought maybe I was wrong, maybe it's not a NAT/ddns toolchain, maybe it's something more complex that I'm too dumb to understand. But if my thesis that it's NATware is right, it makes sense to market it as a security product, it fooled me for one, but it also passes as a quality product for an organization, and they feel they are getting a security product when they are actually signing the purchase request of a developer that is applying networking techniques they learned from managing a videogame server.

I'm still not convinced that IPv6 is a good thing. I think that we should have doubled down on sharing IP addresses. Both for consumbers (NAT) and for servers (NAT, TLS/HTTP reverse-proxying). It just solves all problems with IP address exhaustion. And the fact that consumers can't just directly connect to each other is a feature.