IPv6 autoconf addresses with changing RAs...

[Barry Bouwsma]

> > What I want to happen, is that when the new IPv6 address is autoconf'ed,
> > the old one should disappear from the interface.  (I've been too impatient

> Does the following behavior of rtadvd(8) help you?

Yes, thank you, Jinmei-san!  Excellent!  Except,

> At least rtadvd contained in FreeBSD 4.8R seem to support this
> behavior.

which explains why the man page I have says nothing about it, nor would
it work like that for me.  Because I still have most of a FreeBSD 4.5
userland, although a recent 4.9-RC kernel.  :-P

But now I have compiled a RELENG_4 version of `rtadvd' and installed
it on the router, changed the addresses, and seen exactly what the
man page described:
  On the host, seen after changing an address on the router:
ed0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        [snip]
        inet6 2002:d507:7774:0:200:c0ff:fefc:19aa prefixlen 64 deprecated autoconf
        inet6 2002:d570:7774:0:200:c0ff:fefc:19aa prefixlen 64 autoconf
[I'm offline, but these are the leftover IPv4-based addresses from
 earlier, and a change to test this feature...]
        [snip]
[17:46:50]root at NOSPAM.spam.NOSPAM.spam.NOSPAM.dyndns.dk:/usr/src/usr.sbin/rtadvd{1490}# ping6 2002:d570:7774:0:220:afff:fed4:dbcb
PING6(56=40+8+8 bytes) 2002:d570:7774:0:200:c0ff:fefc:19aa --> 2002:d570:7774:0:220:afff:fed4:dbcb
16 bytes from 2002:d570:7774:0:220:afff:fed4:dbcb, icmp_seq=0 hlim=64 time=607.904 ms

This works perfectly, and I think I no longer need to poke `rtadvd' with
`rtsol' when I assign the IPv6 address(es) each time.

The only thing it seems I must still do by hand, is for the host to
determine its IP is changed, and notify the dynamic DNS server of this
address, and for that I believe I must still use the cron job which I
had hacked to delete the old IPv6 address after detecting a change.


That might teach me to update my whole machine, rather than only the
parts which break with a new kernel...  Or maybe not, I am lazy...

Many thanks again!

Barry Bouwsma
(above e-mail works for IPv6; dropping the hostname part only may make
 it work on IPv4 or not; dropping it entirely won't hurt either)