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Backwards compatibility can not work. You can not answer an IPv6 packet with IPv4. There is no room in the header for the much bigger source/return address. Yo

by okket 9y ago

Backwards compatibility can not work. You can not answer an IPv6 packet with IPv4. There is no room in the header for the much bigger source/return address. You can try to do hacks like NAT (like you probably do in your home IPv4 network, which breaks/stops any peer-2-peer protocol). The IPv6 version is called DNS64/NAT64, and it breaks even more things, e.g. DNSSEC. Because it not only requires network address translation (lying about your IP), but also rewriting DNS records (lying about signed DNS records). The only sane way forward is get rid of IPv4 as fast as possible (even if 'fast' means a decade or two).

mSparks43 9y ago
IPv4 + NAT is much more sane than IPv6 IMHO. Seriously, it should not be the default that every single device on your network is visible to the great wide world. Therein be demons. Especially not all these internet of things devices that any script kiddy can make surrender all its secrets. Plus, have you ever actually even tried a setup of an IPv6 local network? You try typing 2001:0db8:85a3:0000:0000:8a2e:0370:7334 into the address bar 50 times in a week to tweek router settings and see how enamoured you are with the protocol. Furthermore, you know whats easier to type in? rrcc5uuudhh4oz3c.onion
anilgulecha 9y ago
I don't mean it that way. Yes, on-the-wire format would have changed, maybe there would have been a required transition from v4 to v4.1, which could then have been backward compatible to v6. To be fair, I don't think the authors of v6 at the time realized how much friction an alternative IP stack would cause.
- pas 9y ago
  That .1 change has __all__ of the same (and maybe a bit more) problems as the move to v6. (Because it makes things even more complicated, now you'll have not two incompatible but about three things.) And of course the problem is/was of economics. No incentive to change, v4 is good enough for now, for the incumbents. And even if large companies with new users were running out of v4, they can afford trading netblocks and/or carrier grade NAT devices, both are cheaper than telling others to upgrade (and you'd lose customers/subscribers otherwise).
djrogers 9y ago
> You can try to do hacks like NAT (like you probably do in your home IPv4 network, which breaks/stops any peer-2-peer protocol). That’s demonstrably untrue. Sure p2p protocols and NAT devices need to account for NAT, but to imply that they’re impossible to use with NAT is just silly. Many p2p protocols work via NAT all the time...
- okket 9y ago
  Sure, you can add another layer of hacks like UPnP or NAT-PMP to work around the breakage a bit. Or try to use side effects like NAT boxes waiting UDP responses when they forward such a packet. And you can spend the rest of day telling yourself this is totally fine, because it works most of the times. Or could step back and see that this a terminally ill protocol on life support.

by okket 9y ago

mSparks43 9y ago

IPv4 + NAT is much more sane than IPv6 IMHO. Seriously, it should not be the default that every single device on your network is visible to the great wide world. Therein be demons. Especially not all these internet of things devices that any script kiddy can make surrender all its secrets. Plus, have you ever actually even tried a setup of an IPv6 local network? You try typing 2001:0db8:85a3:0000:0000:8a2e:0370:7334 into the address bar 50 times in a week to tweek router settings and see how enamoured you are with the protocol. Furthermore, you know whats easier to type in? rrcc5uuudhh4oz3c.onion

anilgulecha 9y ago

I don't mean it that way. Yes, on-the-wire format would have changed, maybe there would have been a required transition from v4 to v4.1, which could then have been backward compatible to v6. To be fair, I don't think the authors of v6 at the time realized how much friction an alternative IP stack would cause.

pas 9y ago
That .1 change has __all__ of the same (and maybe a bit more) problems as the move to v6. (Because it makes things even more complicated, now you'll have not two incompatible but about three things.) And of course the problem is/was of economics. No incentive to change, v4 is good enough for now, for the incumbents. And even if large companies with new users were running out of v4, they can afford trading netblocks and/or carrier grade NAT devices, both are cheaper than telling others to upgrade (and you'd lose customers/subscribers otherwise).

djrogers 9y ago

> You can try to do hacks like NAT (like you probably do in your home IPv4 network, which breaks/stops any peer-2-peer protocol). That’s demonstrably untrue. Sure p2p protocols and NAT devices need to account for NAT, but to imply that they’re impossible to use with NAT is just silly. Many p2p protocols work via NAT all the time...

okket 9y ago
Sure, you can add another layer of hacks like UPnP or NAT-PMP to work around the breakage a bit. Or try to use side effects like NAT boxes waiting UDP responses when they forward such a packet. And you can spend the rest of day telling yourself this is totally fine, because it works most of the times. Or could step back and see that this a terminally ill protocol on life support.