@bonifartius @p @slashb Taking the bait part 2:

>why? not being routed is what firewalls are made for.

That assumes that everything that runs on IPv6 at home has properly functional firewalls. Spoiler alert: It doesn't and never will. Especially when the router acts only as a gateway without proper firewall which is almost always because UPnP exists and somehow is always enabled by default

>not being routable by default is a side effect of NAT, not a feature.

No this is a feature. LAN as the name says is _local_. The idea that a machine on my _local_ network gets a routable address everywhere by default as envisioned when the protocol was made is insane and there's no questioning about that. Especially if it is done automatically like now.

>if you don't have a router set up to announce the route for slaac or dhcpv6 your devices don't get routable addresses.

How this works is that ISP announces your assigned range and that's it. The fact that the specific address isn't announced like "Hey, I exist" changes almost nothing. It will still get routed to your home by the ISP. You can also knock in the ranges rather easily, or just look at DHT from BitTorrent and now you have an actual address. This knocking is already a common thing in botnet router exploitation.

>there is an v4 version of this when there is no dhcp around, 169.* subnet or something.

Yes, and only Windows uses that. It's called APIPA.

>link local addresses aren't routed.

They are locally and nothing asks you if you want that.

>i don't really see what's the use of a connected networked device but without the right settings to actually work?

To-be-assigned static addresses, general testing, temporarily putting the machine out of the network for whatever reason and more.

>the last 64 bit are the interface address. the first 64 bits for the network already are 32 bit more than the whole address space of v4. i'd have used longer prefixes, but in reality it's not that relevant imo.

The whole point of IPv6 was that we would hopefully never run out of addresses, then ff a decade and we are throwing /64 subnets that describe _one_ machine on the Internet. Does that make sense? The point of v6 was also that we would make P2P networking actually usable with the routable addresses on your local network, which is a good idea on paper, but terribly executed. It never should have been automatic.