Re: Interface promiscuity obscurity in Linux

[Glynn Clements <glynn.clements () virgin net>]

Ricardo Branco wrote:

> Using libpcap to put the interface in promiscuous mode, will cause that
> ifconfig(8) doesn't show it!
>
> libpcap uses setsockopt(..., SOL_PACKET, PACKET_ADD_MEMBERSHIP, ...) with
> PACKET_MR_PROMISC to set the interface in promiscuous mode.
>
> I notified this to the tcpdump-workers mailing list and the problem is
> that the setsockopt() sets the promisc flag in a variable that is not the
> same as the one that the SIOCGIFFLAGS ioctl() reads. I don't have the
> kernel source right now to make this advisory more precise.

This issue was discussed extensively on the linux-net list back in
February, in the thread entitled "IFF_PROMISC bug?":

        http://marc.theaimsgroup.com/?t=101356558000002&r=1&w=2

-- 
Glynn Clements <glynn.clements () virgin net>