[GRLUG] Testing a host's IPv6

[Adam Tauno Williams]

On Sat, 2011-01-15 at 15:03 -0500, Michael Mol wrote: 
> On Sat, Jan 15, 2011 at 2:41 PM, Bob Kline <bob.kline at gmail.com> wrote:
> > Someone mentioned that recent distributions
> > come with IPv6 enabled.  How might one verify
> > that it is enabled?
> >     -- Bob
> Actually, I recently blogged how to probe your network for IPv6 hosts,
> but here's a slightly expanded version.
> Drop to a terminal environment.
> Run "ifconfig", to list your operating network interfaces.

ifconfig is officially deprecated; the "ip" command should be used.

> eth0's IPv6 line says that its address is fe80::a800:ff:fedc:e7/64,
> and that the scope (where that address is valid/meaningful) is "Link".
> That means that it's only valid on the local Ethernet segment. (Well,
> technically, that means it's valid on the local 802 network segment,
> which Ethernet and wifi both fall under, along with things like token
> ring and FDDI.)

Actually, the link-local address is valid on any IPv6 link; even
point-to-point links like PPP or HDLC.  This is one of the many beauties
of IPv6 [one quickly realizes how badly IPv4 sucks] in that you just
ignore PtP links and they just magically work - there is no reason for
end-points to be globally routable so no screwy /252 subnets and the
like.  Hosts at each end can exchange routing information and route
traffic over that link to other available subnets (nobody cares about
the PtP link, only what is on the other side).



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