[alyrik]

Adding SOCKS to NAT boxes and to client devices is easier than IPv6, I warrant; SOCKS is a dead simple protocol, and the client can be slid into the sockets library without the app having to care.

And that's it. There's no need for ISPs to route you IPv6, or to set up tunnels. No need for dual stacks and AAAA records. No need for service providers to provide IPv6 access to their servers.

SOCKS is less restrictive than NAT - the client can know about it and find their external IP/port, it allows incoming connections, it lets the gateway device authenticate users and give them differing quality of service, etc.

[throwaway32]

as stated above, with an approach like 6in4 there is no need for your ISP to route ipv6, or even be aware of its existence.

[alyrik]

Yeah, but what benefit is there as opposed to just sticking with NATv4 or SOCKS?

The real issue here is running out of IPv4s.

We don't really need more IPs for clients - NAT fixes that problem (I just argue that SOCKS could be a better solution, that can work alongside NAT).

We need more IPs for servers. The IPv6 solution is to move clients and servers to IPv6. 6in4 gets around needing to migrate the ISP as well, which is good, but it's still a heap of work that has to be done by people who don't get any material benefit out of it for years, at best. So it won't happen.

[throwaway32]

The benefit is real end to end connectivity without the need for co-operation of everyone along the chain (this is an extremely serious issue, often even one layer of NAT makes trying to get port forwarding a nightmare, imagine 2 or 3) . Its also much more scalable than both. In the long run supporting some kind of gargantuan NAT/SOCKS translation layer for millions of customers is going to be much more expensive than ipv6 support, because IP is fundamentally stateless and designed to scale massively, NAT and SOCKS are not. This becomes a serious concern at larger scales.

[alyrik]

SOCKS gets you end to end (though it's arguably not "real"!) by letting you have listening sockets (which NAT doesn't).

There is indeed a scaling issue with NAT/SOCKS as both need connection state on the gateway device - but, I suspect, the dropping cost of hardware versus the rising cost of IPv4s will favour more hardware. The real question is how it'll stack up against the cost of dropping IPv4 for IPv6 (not the cost of adding IPv6 support alongside IPv4, which isn't that hard).