Re: IPv6 prefix route lifetime

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

On Friday 05 August 2016 01:11:20 Roy Marples wrote:
> With recent (well a few versions ago) changes to dhcpcd(8), it no longer
> destroys prefix routes if there is no reason to (yay, NFS). However,
> this has introduced a new problem that seems to be present in all BSD
> kernels that a freshly added IPv6 address NOT via in kernel RA will add
> the prefix route to it's internal list:
> https://nxr.netbsd.org/xref/src/sys/netinet6/in6.c#650
> 
> However, subsequent calls to re-add the address OR adjust the address
> lifetimes do not update the prefix route times in nd6_rtr.
> This means that the prefix route will timeout no matter what we do, the
> result being that dhcpcd will add a replacement route, but the kernel
> will then remove it (as according to it, it has expired, which is
> wrong).

The issue can be worked around by first adding addresses with infinite lifetimes 
so the prefix route in the "RA" won't timeout.
We can then safely re-add the address with correct lifetimes.

dhcpcd fix is below if anyone wants to test this before I rush out a new 
release to workaround this problem.

http://roy.marples.name/projects/dhcpcd/info/37ca8a2052507e64

Roy