> RFC3513 says this:
>  o An anycast address must not be used as the source address of
>  an IPv6 packet.
>  o An anycast address must not be assigned to an IPv6 host, that
>  is, it may be assigned to an IPv6 router only.
> And to help ensure this, the kernel denies binding to an address marked
> with the anycast flag (see netinet6/in6_pcb.c).
> This was obsoleted by RFC4291, including this change:
>  o The restrictions on using IPv6 anycast addresses were removed because
>  there is now sufficient experience with the use of anycast addresses,
>  the issues are not specific to IPv6, and the GROW working group is
>  working in this area.
> So I think this restriction can now be removed, at least with this
> change, but more might be needed

Certainly in my case the current OpenBSD situation represents a bit too much 
"nanny knows best".

My use-case is anycast DNS with NSD and Unbound.

Both NSD and unbound provide config parameters that allow distinguishing 
between listen address and source address.

But then again, is there any real reason to use the anycast flag ?  To make NSD 
and unbound work I reconfigured to remove the anycast flag from IPv6 addresses 
and nothing seems broken ?

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