Getting/setting eth frame interface for raw socket

Hi

I've written a network monitoring app for linux that displays information about
ethernet frames it receives. It creates the socket as follows:

sock = socket(PF_PACKET,SOCK_RAW,htons(ETH_P_ALL))

My 1st question is , is there a simple way to get the interface name the
frame arrived on or would I have to issue an ioctl SIOCGIFCONF call
and loop through the list of interfaces comparing the MAC addresses?

My 2nd related question is - how can I specify what interface to send an
outgoing frame on when I update the code to write to the socket?

Thanks for any help.

B2003

On Wed, 30 Sep 2009 06:34:22 -0500
(E-Mail Removed) (Gordon Burditt) wrote:
>I'm not sure you can *TELL* the interface name the frame arrived
>on by looping through the list of interfaces comparing MAC addresses.

You can if it has arrived from an ethernet interface.

>Localhost doesn't have a MAC address.
>Lots of virtual interfaces like 'gif' don't either.
>Neither do some of the packets removed from the system, then re-injected
>into it (say, by a userland NATD daemon).
>What about broadcast packets?

None of the above work, which is why I was hoping that there was a way
of obtaining the packets interface directly but I suspect not.

B2003