IPV6_RECVPKTINFO not working for IPv4-mapped addresses on Linux?

Nick Hilliard nick at foobar.org
Thu Jan 23 11:38:51 CET 2014


On 23/01/2014 00:03, Francis Dupont wrote:
> => recvfrom() returns the peer address, i.e., the source address of
> the request, when you need the local address, i.e., the destination
> address.

I was thinking of recvmsg(), as someone else pointed out.  It's been way
too long since I've looked at any of this.

> => I'd like to say VRRP needs to be fixed but here the reasonable
> solution is to be notified...

it's implementation specific.  There's nothing in the rfc to say that you
can or can't have the virtual ip address configured on a dummy interface on
all vrrp boxes; only that the VIP should not answer to ARP requests on the
backup units.  Some implementations swap the VIP between the primary and
backup devices; others nail it up and do clever arp tricks.

Also the same issue relates to any FHRP, e.g. CARP which is specifically
aimed at service based failover in order to avoid the patent issues
relating to USPTO #5473599, because VRRP does network failover and CARP
does services failover and obviously they're completely different amirite.

Nick




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