I've been trying to use Wireshark (Ethereal) on a Linux box to sniff packets to/from other PCs plugged into the same bank of 4 LAN ports on the back of WRT54GL. I can only see packets to/from the Linux box itself, or broadcasts. I am aware of the need to run the Wireshark software in promiscuous mode to make this work, and I am doing that (supposedly). It occurred to me, could it be that the 4 LAN ports on the WRT54GL router are NOT equivalent to an unswitched hub, which would an explanation why this isn't working. The router is running DD-WRT but I don't think that is relevant.