[ILUG] Promiscuous mode

[Dave Wilson]

So I'm playing with VMware - very neat indeed - and notice that it sets
promiscuous mode, presumably so it can listen on whatever IP address that you
assign to the virtual machine without having to mess too much with the host
OS. But while this appears in /var/log/messages, I notice it doesn't turn up
in /sbin/ifconfig

If I su to root and issue /sbin/ifconfig eth0 +promisc, I notice that PROMIC
appears in amongst the other details in the output of /sbin/ifconfig eth0.
But if I issue a /sbin/ifconfig eth0 -promisc while VMware's running, I see is
/var/log/messages:

Nov  9 12:05:24 olethros kernel: device eth0 left promiscuous mode
Nov  9 12:05:24 olethros kernel: bridge-eth0: lost IFF_PROMISC
Nov  9 12:05:24 olethros kernel: eth0: Setting promiscuous mode.

Not a packet was lost while pinging the virtual machine's address, but
PROMISC no longer appears in the description given by /sbin/ifconfig eth0.

Is there a sure fire way to tell whether an ethernet interface is in
promiscuous mode or not? Something in /proc maybe?

Cheers,
Dave

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