Hi:
	I'm confused about the comment "set the filter in assembly
language" (?) The BPF header file defines a number of C macros that are
used to set up the BPF structures to do the filtering that you require.
In your other posting, you indicate that you can send and receive the
ethernet packets but I guess that the problem is that you don't have the
filtering set up?

If you take a look here
http://www.gsp.com/cgi-bin/man.cgi?section=4&topic=bpf 
you will see some examples at the end, one of which is how to filter to
accept reverse ARP requests.  You can see how the first thing it does is
filter on the Reverse ARP filter type and this is followed by a filter
on the request field.  You should just be able to remove the check for
the arp request, leaving only the ethertype filter in there.

	Robert.



-----Original Message-----
From: Beniz VB [mailto:community-noreply@qnx.com] 
Sent: Wednesday, February 04, 2009 2:40 AM
To: ionetmig-networking
Subject: Re: RE: How to set filters for capturing ethernet raw packets
in BPF?


Hi Robert,

            Thanks for your reply. I have gone through the links that
you have sent to me. But I couldn't implement the filter in my program.
I have a doubt whether I should set the filter in assembly level. Can
you please send me one example C code which can filter raw ethernet
messages from the network (in QNX 6.4).

           In my sender program I'll send an ethernet frame (destination
hardware (MAC) address [6bytes] + source hardware (MAC) address [6
bytes]  + etherl type [2 bytes]  + payload [46 - 1500 bytes] +FCS [4
bytes].)

          In my ethernet frame, I'll put ethertype as 0x9999, inorder to
identify it as my frame while receiving. So in BPF receiver, I should
capture frames which contain ethertype = 0x9999 only. Can u please tell
me how to write a bpf filter program in C for capturing my frame (QNX
6.4).


Thanks & Regads,
Beniz V B

_______________________________________________
io-net migration
http://community.qnx.com/sf/go/post21380