Re: bin/53705: dhcpcd spams syslogd

[Roy Marples <roy%marples.name@localhost>]

On 10/04/2019 16:08, Joerg Sonnenberger wrote:
> On Wed, Apr 10, 2019 at 01:15:01PM +0000, Roy Marples wrote:
> >   Please create a new PR for it because there really is no right way of
> >   solving this.
>
> "Ignore the DHCPv6 bit for RAs from the following address" would allow
> to avoid the problem, wouldn't it?

No, the issue Robert is seeing here is that the RA says "I'm a default 
router, get an address via DHCPv6" and the DHCPv6 server says "I have no 
address for you".

Thus he just ends up with a default inet6 route, no addresses other than 
the default link local address and as such gets timeouts when something 
wants to use inet6 - such as a cvs up.

This is noted in RFC7084:
https://tools.ietf.org/html/rfc7084#section-3.2.1
   At the time of this writing, several host implementations do not
   handle the case where they have an IPv6 address configured and no
   IPv6 connectivity, either because the address itself has a limited
   topological reachability (e.g., ULA) or because the IPv6 CE router is
   not connected to the IPv6 network on its WAN interface.  To support
   host implementations that do not handle multihoming in a multi-prefix
   environment [MULTIHOMING-WITHOUT-NAT], the IPv6 CE router should not,
   as detailed in the requirements below, advertise itself as a default
   router on the LAN interface(s) when it does not have IPv6
   connectivity on the WAN interface or when it is not provisioned with
   IPv6 addresses.  For local IPv6 communication, the mechanisms
   specified in [RFC4191] are used.

https://tools.ietf.org/html/rfc7084#section-4.3
   ULA-5:  An IPv6 CE router MUST NOT advertise itself as a default
           router with a Router Lifetime greater than zero whenever all
           of its configured and delegated prefixes are ULA prefixes.

The other issue is that we don't do anything with ICMP unreachable which 
the router should have sent back anyway.

Roy