[clug] IPv6 in Canberra

[Bob Edwards]

On 25/06/17 16:46, Scott Ferguson via linux wrote:
 > ...
> Note for others - "ip a" will show network details, if you have IPV6
> enabled you'll see an IPV6 address e.g.:-
> 3: wlp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP
> group default qlen 1000
>     link/ether 00:22:fb:c4:6d:04 brd ff:ff:ff:ff:ff:ff
>     inet 192.168.1.122/24 brd 192.168.1.255 scope global dynamic wlp2s0
>        valid_lft 2532sec preferred_lft 2532sec
>     inet6 fe80::f93:8ed:dbd6:813c/64 scope link
>        valid_lft forever preferred_lft forever
>
>
> In this case the inet6 address starts with "fe", which means it does
> *not* support IPV6 internet (nor do addresses starting with "::", "fc",
> or "fd")

Or, if you don't want to remember "fe80" etc. the "link" flag in the
output on the IPv6 line tells you that it is a "link-local" address
(has "link" scope) which means it won't be routed. So it will exchange
IPv6 datagrams with other hosts on the same link-layer, but not to
nodes outside your LAN.

Repeating this exercise on one of the machines I administer at ANU
gives:

3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast 
state UP group default qlen 1000
     link/ether 68:05:ca:1a:c4:51 brd ff:ff:ff:ff:ff:ff
     inet 150.203.164.18/24 brd 150.203.164.255 scope global eth1
        valid_lft forever preferred_lft forever
     inet6 2001:388:1034:2900::12/64 scope global
        valid_lft forever preferred_lft forever
     inet6 fe80::6a05:caff:fe1a:c451/64 scope link
        valid_lft forever preferred_lft forever

there are two IPv6 addresses: a "link-local" address and a "global"
address. Alas, the ANU DNS servers don't seem to want to reverse the
global IPv6 address (although you can do a reverse lookup of the IPv4
address, and then do a forward lookup on that DNS name to see the
global IPv6 address in the DNS).

cheers,

Bob Edwards.

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> Kind regards
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