Programming interface MAC filter without enabling PROMISC on
an interface from user space.
Bruce M. Simpson
bms at FreeBSD.org
Mon Jan 14 09:13:17 PST 2008
Tom Judge wrote:
> Thanks for the response. I have a quick grep of the src tree to find
> an example of this being used and only found the following from
> wpa_supplicant and I have a few questions:
> * I am presuming that this will do what I want, am I correct?
Yes, it will attempt to add the given link layer multicast group to the
ifnet's underlying device driver.
> * If I was only ever to add the address to an interface an never
> delete it would this cause any problems? I.e. when lldpd ends, or is
> restarted and tries to add the address again?
SIOCADDMULTI is very low level, no resource tracking is performed; I
changed its semantics to only allow one userland opener so that
in-kernel refcounting would work, as there is no per-process or
per-client resource tracking -- so it's a really good idea to clean up
> * Alternatively is there a way to query the filter to ask what
> addresses it is currently programmed for?
Nope, there is no userland or kernel API for that unless you hack up the
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