FreeBSD does not reply to IPv6 Neighbor Solicitations

[Victor Sudakov]

Paul Mather wrote:
> >>>> Why could it be that a FreeBSD 12.2 host does not reply to ICMPv6
> >>>> Neighbor Solicitations from the router?

[dd]

> > 
> > $ ifconfig re1
> > re1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
> >        options=8209b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC,LINKSTATE>
> >        ether c4:12:f5:33:c9:7c
> >        inet 192.168.170.5/24 broadcast 192.168.170.255
> >        inet6 fe80::c612:f5ff:fe33:c97c%re1/64 scopeid 0x2
> >        inet6 2001:470:ecba:3::5/64
> >        media: Ethernet autoselect (1000baseT <full-duplex>)
> >        status: active
> >        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
> 
> 
> I notice your nd6 options do not include ACCEPT_RTADV.  Perhaps this
> is a reason why your interface is ignoring routing messages?  

Well, Neighbor Solicitations (ICMPv6 type 135) and Neighbor
Advertisements (ICMPv6 type 136) are not exactly routing messages, they
are the equivalent of the ARP protocol in IPv6, and AFAIK should work
between any two IPv6 nodes to map L3 addresses to L2 addresses, even if
there are no routers on the segment. Correct me if I'm wrong.

You may be right but then it is certainly a bug. Unfortunately I cannot
reproduce the problem with any reliability, this thing works more often
than not.

> My interface ifconfig shows "nd6
> options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>"

> 
> I also use a statically-defined[*] IPv6 address, but include "accept_rtadv" in the interface definition in /etc/rc.conf.  Furthermore, I also set rtsold_enable="YES" to send router solicitation messages on the interface.

This would add one or two autoconfigured global IPv6 addresses to your
interface. There is no harm in that, I agree, but it's important to
understand if this is a bug and can be reproduced and reported.

> 
> [*] As well as a static IPv6 address I also enable SLAAC to get autoconfigured and privacy addresses on the interface.
> 

I see your point, this makes sense, but I would like to try and isolate
the problem.

-- 
Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
2:5005/49 at fidonet http://vas.tomsk.ru/
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