If you want to be part of the global address space and you are
behind a NAT box, get a PPP account outside your NAT box and
connect to it with TCP or SSH or SSL or UDP or HTTP or whatever
(see for example the use of PPP over telnet, in the www.ora.com
Turtle PPP book.)
What IPv4 NAT issue doesn't that solve, if any?
And for those of you who will claim it is inefficient, just how
inefficient is it, in terms of measurable quantities?
Whether it costs more than IPv6 over UDP, I don't know, but I
strongly suspect that in a vast majority of real-life cases it
does not.
Cheers,
James