ipv6 question!

[Markus Schönhaber]

Michael Casey:

> If I would have an IPv6 address [home pc, behind a router - supporting ipv6
> e.g.: openwrt, ISP gives ipv6], then I can see an IPv6 address with
> ifconfig, on the PC e.g.: "Z"
> So that's my "very unique address". - "Z"

Generally, your ISP won't assign you "a" IPv6 address but an IPv6
prefix, i. e. an (*really* big) IPv6 subnet for you to use.

> Can that be "seen on the internet", the "Z" address? so anyone can ping me
> from outside, or do an nmap?

Depends on what your router does with the assigned prefix.

> Or are there private addresses what the router gives to my pc.: eg.: with
> ipv4 a router could give 192.168.1.10... and that IP couldn't be
> pinged/nmapped from outside (More Secure???)
> Because I heard that there will be no NAT with IPv6?

There are ranges of IPv6 addresses the one could call "private", the
link local addresses. On an Ubuntu default installation, your network
devices will already have link local IPv6 addresses assigned - whether
or not your ISP supports IPv6 connectivity to the world.
Look, for example, at the output of
ifconfig
and you'll see lines looking like this
|          inet6 addr: fe80:...
These addresses are only reachable in your local subnet. If you want to
make a machine in your local net accessible to the world via IPv6,
you'll have to take additional measures like setting up a router
advertisment or a DHCPv6 daemon that hands out global IPv6 addresses to
your devices (stemming from the IPv6 prefix your ISP assigned to you).

BTW: Additionally there are (or have been) site local IPv6 addresses
(fec0::/10) which were intended to replace local IPv4 addresses like
192.168.0.0/24. Their use is now deprecated, though.

-- 
Regards
  mks