We had some on-premise hosting, and I figured the easiest thing would be to keep the existing network LAN addressing. Each LAN had a different IP range, so it would be no problem for them to share the same ethernet network, as long as only one of the three LANs provided DHCP for the PCs.

We already had a Cisco router for internet access. That should be able to provide routing between our three LANs, right?

That was a terrible idea, as local traffic was bottlenecked on this small router that wasn't designed for the job. Transfers between LANs were as slow as they'd been when we in different physical locations.

I spent an hour or two consolidating the LAN onto a single IP subnet, and everything worked as you'd expect.

Technically it's not NAT64 today. Different prefix for one, but it's also not translated at the IP layer (yet). For TCP, we terminate the TCP in tailscaled and make a new TCP connection out and switch them together, so packets are not 1:1 end-to-end.

We also had grander plans for the 32 "site-id" bits in the middle there. Instead of just a 8-bit (now 16-bit) "site ID" number in there, you could actually put the 32-bit CGNAT IPv4 address of any peer of yours, and then access its IPv4 space relative to that node, without any configuration.

Say you have an Apple TV plugged in at home.

Then you're at a coffee shop and want to access something on your LAN and don't have a subnet router set up.

You should be able to `ssh 10-0-0-5-via-appletv.foo-bar.ts.net` and have MagicDNS map that "appletv" as the "Site ID" and put its 32-bit CGNAT address in, and then parse out the 10.0.0.5 as the lower 32-bits, and then have Tailscale route your packets via your home Apple TV node.

All subject to ACLs, of course, but we could make it a default or easy-to-enable recommended default that you could do such things as an admin for your self-owned devices.

So why it's called "4via6"? That was just kinda a temporary internal name that ended up leaking out to docs/KB and now a blog post, apparently. :)

Not a single purely negative comment here as of the time i'm writing this. Maybe a criticism or two, but no one has a "dislike".

Thanks and I apologize in advance for imposing on you.

As a bonus, my family can call the ISP's tech support if anything dysfunction while I'm traveling: my self-hosting crap is perfectly independent from the ISP's standard service. And wait, there's more - I can add services anywhere, such as a backup server at my parent's, regardless of their configuration and with no impact.

So yes, Tailscale all the things... I'm nostalgic for the IPv6 flat end-to-end dream but, in our world of ubiquitous IPv4 NAT horrors, Tailscale functionally surpasses it.

    > Honest question- Would a full IPv6 implementation across the board, hurt Tailscale's M.O. and bottom line, assuming all routing worked properly (a big assumption, to be sure)?

Maybe, but even asking the question is kind of conspiratorial. Companies like Cisco, Google, and Apple have been pushing IPv6. A small startup can't somehow hold back IPv6 "world domination" even if they tried.

The key thing it gives you is the ability to define policies about who can talk to what, irrespective of where the endpoints actually are, while also cryptographically protecting your traffic.

On the other hand, if you never ever use anything but HTTPS, then you probably don’t need it and you could do away with it today.

But I haven’t the foggiest what the next question is.

Many network technologies/services exist to manage suboptimal circumstances, which would not be needed in better circumstances.