dhcpcd-discuss

Hi

On 15/09/2017 10:31, harald.albrecht wrote:
> Hi,
> 
> is there a configuration option to stop dhcpcd installing IPv6 reject
> routes in the context of prefix delegation?

No.

> In my use case I need to
> request a single /64 prefix from an upstream/delegating router, but I
> don't want to assign it to any interface because this traffic is handled
> by a snooping user daemon. Instead of the reject route I need to install
> a blackhole route, as the traffic gets handled so the Linux kernel must
> not send ICMPv6 unreachables.
> 
> Could this be done in a hook script instead: removing the
> dhcpcd-installed reject route and setting my blackhole route? Are there
> any conflicts to be expected, such as dhcpcd trying to reinstall its
> reject route?

No, because dhcpcd will rebuild the routing table at key points.
Most of the time hook scripts are called, but there are corner cases
where they are not.

> Please note that the Linux kernel doesn't allow a higher priority
> blackhole route to be installed alongside the lower priority reject
> route -- at least that is what I see, but maybe I've missed something
> here and these two routes can be installed simultaneously??

I don't know about Linux, but I'm pretty sure that on NetBSD at least
two routes cannot exist to the same destination and thus the same issue
will occur.

I see no reason why an option to turn the reject into a blackhole cannot
exist.

Roy