Using an IPv6-only internal network in a real-world environment

Problem: Not all servers which are available on the IPv4 Internet have IPv6-connectivity

Step 1: allowing a client application to talk to an IPv4 host through IPv6 packets

We will try to allow a IPv6-aware program, such as lynx, on setzer to talk to an IPv4-only machine on the internet, such as http://www.google.com.

To do this, the OS on mintzer would somehow have to process these addresses and translate them to IPv4-connections. I collected some links:

http://www.cs.washington.edu/homes/mef/research/napt/reports/usenix98/ (local copy)
http://www.kfu.com/~nsayer/6to4/noipv4.html, discussing the topic informally (local copy)
draft-ietf-ipngwg-addr-arch-v3-11 describes "IPv4-mapped IPv6 addresses" of the from '::ffff:131.174.122.207', but not how they are used.
RFC 2766: Network Address Translation - Protocol Translation, describing a solution (NAT-PT)
RFC 3142: An IPv6-to-IPv4 Transport Relay Translator, describing a solution (TRT)
this document describes the differences between TRT and NAT-PT (local copy)
http://www.ipv6.or.kr/english/natpt-overview.htm is a rather old implementation of NAT-PT for linux from British Telecom
pTRTd is a TRT implementation for linux written by the same guy who wrote radvd for linux, Nathan Lutchansky.

I chose pTRTd. It's experimental software, but oh well. By default it doesn't use the '::ffff:131.174.122.207'-addresses, but the site-local addresses, like fec0::ffff:0:0:131.174.122.207. I decided to stick to that.

So I added the TUN/TAP modules on mintzer, installed pTRTd. It pretty much worked right away, I could lynx to fec0:0:0:ffff::216.239.39.101. I added the following record to the bzzt.net-zone on the DNS on mintzer:

google  IN      AAAA    fec0:0:0:ffff::216.239.39.101

and - surprise, surprise - it couldn't lynx to google.bzzt.net. I couldn't even ping. 'dig -t aaaa google.bzzt.net' worked, 'ping6 fec0:0:0:ffff::216.239.39.101' worked, 'ping6 google.bzzt.net' didn't. However, when I added a line to /etc/hosts, it worked fine. The next day, it also worked without the line in /etc/hosts.