Maybe just set promiscuous mode?
Xircom PCMCIA Ethernet Adapter Issues
CBEM56G sleeps 'til a little nudge thru tcpdump(?!) (Kai Krebber)
Date: 1999, Nov 30
From: David Hinds <email@example.com>
Try doing "ifconfig eth0 promisc".
I think there's still something broken in how the driver sets up the
chip's address filtering.
This works on RBEM100-56G by Chris Hanson, 1999, Dec 10
try ifconfig too by Richard, 1999, Dec 11
to: "Maybe just set promiscuous mode?"