When capturing packets on a PF_PACKET/SOCK_RAW socket bound to all
interfaces, there doesn't appear to be a way for the filter program to
actually find out the underlying hardware type the packet was captured
on, such as is reported by the sll_hatype field of the struct sockaddr_ll
when the packet is sent up to userland.
Unless I've managed to miss a trick somewhere, this would seem to put a
fairly fundamental blocker on actually being able to filter in such
packets. Granted there's the SKF_OFF_NET area to inspect at the e.g. IPv4
level, but this makes it impossible to do anything on e.g. the Ethernet
level.
See attached for a patch to add an SKF_AD_HATYPE field, up among the
other special access fields around SKF_AD_OFF.
--
Paul "LeoNerd" Evans
leonerd@leonerd.org.uk
ICQ# 4135350 | Registered Linux# 179460
http://www.leonerd.org.uk/