IPv6: "xxx::x already configured" in logs... why?

[Rui Paulo]

On Wed, 2017-03-29 at 21:46 -0500, Lawrence Stewart wrote:
> [resurrecting an old thread]
> 
> On 19/06/2014 23:08, Hiroki Sato wrote:
> > Larry Rosenman <ler at lerctr.org> wrote
> >   in <20140619140801.GA65420 at thebighonker.lerctr.org>:
> > 
> > le> > le> Ideas? (I may be an idiot, so any criticism welcomed).
> > le> > le>
> > le> > le> if you need the 1841's config, I can supply that as
> > well.  It's using a Hurricane
> > le> > le> electric Tunnel.
> > le> >
> > le> >  How frequent were the log message added into
> > /var/log/messages?  And
> > le> >  when did it start to happen after boot.  Just after lagg0 is
> > le> >  configured?
> > le> >
> > le> > -- Hiroki
> > le> Looks like:
> > le>
> > le> Jun 12 07:00:01 thebighonker kernel: in6_ifadd:
> > 2001:470:1f0f:3ad:223:7dff:fe9e:6e8a is already configured
> > 
> >  Thank you.  Three more questions:
> > 
> >  1. output of "ifconfig lagg0", "ifconfig bce0", and "ifconfig
> > bce1".
> > 
> >  2. output of "netstat -s -i".
> > 
> >  3. output of "ndp -p".
> > 
> >  The cause of the message is that the automatically-configured
> > address
> >  is not recognized as "configured" one and FreeBSD IPv6 stack is
> >  trying to add it every time a Router Advertisement message is
> >  received.  I am still not sure why it happened, but the above
> > three
> >  would help for further investigation.
> 
> I've recently set up a VPS with v6 and am seeing the same "in6_ifadd:
> <v6_addr> is already configured" messages in response to periodically
> received router advertisements every 5-10 mins. The host is a KVM-
> based
> virtual machine with vtnet-based NIC. v6 is fully functional with the
> statically assigned v6 address, but the spam in /var/log/messages is
> annoying.
> 
> 
> FreeBSD revision:
>   FreeBSD lauren 12.0-CURRENT FreeBSD 12.0-CURRENT #0 r315059: Sun
> Mar
> 12 20:44:50 AEDT 2017
> root at builder-head-amd64:/usr/obj/lauren/usr/src/sys/GENERIC-
> NODEBUG  amd64
> 
> 
> Relevant bits from /etc/rc.conf:
>   rtsold_enable="YES"
>   ipv6_activate_all_interfaces="YES"
>   rtsold_flags="-aF"
>   ifconfig_vtnet0_ipv6="inet6 <v6_addr> prefixlen 64"
> 
> 
> Interface:
>   vtnet0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0
> mtu 1500
> 
> options=6c07bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_H
> WCSUM,TSO4,TSO6,LRO,VLAN_HWTSO,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
>         ether <mac>
>         inet <v4_addr> netmask 0xfffffe00 broadcast <v4_bcast>
>         inet6 <v6_linklocal>%vtnet0 prefixlen 64 scopeid 0x1
>         inet6 <v6_addr> prefixlen 64
>         nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
>         media: Ethernet 10Gbase-T <full-duplex>
>         status: active
> 
> 
> I would have thought rtsold should be able to play nice with
> statically
> assigned v6 addresses... any ideas?

Hmm, why would it?  If you setup an IPv6 address and then there's a
router solicitation advertising the same address, the log message makes
sense.

I don't think you should run rtsold if you have a static IPv6 address.

-- 
Rui Paulo