Re: bin/53705: dhcpcd spams syslogd

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

The following reply was made to PR bin/53705; it has been noted by GNATS.

From: Roy Marples <roy%marples.name@localhost>
To: Joerg Sonnenberger <joerg%bec.de@localhost>, gnats-bugs%netbsd.org@localhost
Cc: roy%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost,
 kre%munnari.OZ.AU@localhost
Subject: Re: bin/53705: dhcpcd spams syslogd
Date: Wed, 10 Apr 2019 18:08:16 +0100

 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