Ethereal-users: Re: [Ethereal-users] Trying to use Ethereal in promiscuous mode with 3C905c-tx N

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From: Guy Harris <guy@xxxxxxxxxx>
Date: Wed, 21 Feb 2001 16:53:58 -0800 (PST)
> I am running RED HAT 7.0 (kernel 2.2.16-22) and Ethereal 0.8.15 with
> 3COM NIC (3c905c-TX) and the spec sheet said that the NIC supports
> promiscuous mode but I can only see my own traffic.
> 
> I have check to make sure I am attached to a hub and not a Ethernet
> switch.

...and presumably have also checked to make sure the hub isn't a
switching hub.  (I think there are some devices called "hubs" that are
really switches.)

If so, perhaps the Linux driver doesn't put the card into promiscuous
mode, or something.  Try running tcpdump; if it also sees only traffic
sent to or from the machine on which it's running (plus broadcast and
multicast traffic), ask Red Hat why promiscuous mode isn't working.

(NOTE: the tcpdump that comes with Red Hat 6.1 and later does *not* do
promiscuous mode by default; you have to specify an interface with the
"-i" flag and turn promiscuous mode on with the "-p" flag.  This is a
function of tcpdump, not libpcap, so that particular tcpdump
"improvement" doesn't affect Ethereal.)