IPv6, in a way, takes the concept of a MAC address and puts it on steroids. This became evident to me when I learned about EUI-64 addresses. And then my brain melted when I learned that any interface can be assigned an arbitrary number of unique addresses with varying purposes or contexts because the address space is truly *that big*.

When I consider that quality of IPv6’s design, it communicates to me an old and ideal vision of what we thought the internet would and should be - a hyper-connected, shared infrastructure where [Layer 3] identity is universally unique such that connectivity between any two arbitrary nodes is possible (which obviously isn’t true for NAT w/ overload).

I’m just a lowly SysAdmin who finally decided to get his CCNA - so I’m a nobody - but as I worked through the material I felt like I was paging through a history book or biography of how the Internet’s life came to be and all the mistakes made along the way. Most features felt like patches for design considerations that were overlooked. Examples: DHCP Snooping, STP’s various * Guards, and the mere fact that Layer 2 and Layer 3 addresses are distinct concepts.

I don’t think there’s any disagreement that NAT was co-opted as a security feature. I never hear that said in a positive way, either. I think if we were to start over, with IPv6 as the default assumption, the tools we’d develop for network security would look very different, but not at all impossible or any more difficult.

But again - I’m a nobody. Just thinking out loud here.

When I want to debug reachability concerns, it's a shame that I can only use ping/traceroute between the non-NAT peers, and then have to SSH to my reverse proxy to do yet another ping to the backend. Similar for tcpdump.

This is the cost to splitting your routing between layer 3 and 4.

I'm now IPv6 everywhere, and so I get to just use ping. Much simpler.

Further, protecting IPv6 services is simpler, because I can terminate (m)TLS on the backend. With a reverse proxy on another host, I have to have yet another means of securing the proxy-backend path. Yet more complexity!

> And the fact that consumers can't just directly connect to each other is a feature.

Consumers should be protected by firewalls. That's independent of routing.

P2P communication is also a feature, which an entire class of applications would love to make use of. Instead, we need to spawn (and PAY for) TURN and STUN servers

Reverse proxies work because they're not behind restrictive NATs, and having a few central servers that are not behind Symmetric NAT is a surefire way to establish an ISP-granted monopoly. Even if that somehow worked, this completely breaks P2P for consumers (which I think you intend) as well as torrenting without, again, a central NAT-punching TURN-like server. So yeah, address exhaustion is done but so is the Internet as we know it.

Easier just to say it's a thing, like a force of nature.

New network growth (mobile, Africa, Asia) uses it, old growth stays on v4 and will eventually roll over. People with address space usually don't need much more, but the IPv6 space better reflects how connected the world is - we're gonna need a bigger address space than v4, that's for sure.

New protocols shipped quickly on rough consensus and working code and weren't perfect - some left all kinds of undefined behavior, or lacked clear advantages over predecessors and competing protocols.

ipv6 is a window for every buttock. I don't see this as a good thing.