Is is possible to make a passive network tap using only three jacks, with only one jack and one NIC used for the tap itself?   I am accustomed to making these with 4 jacks, with 2 being used for the tap.  With 4 jacks, each of the taps gets a half duplex signal in a full duplex config.  This forces you to bridge your two NICS if you want to sniff both directions of traffic.  I am just wondering if there is a more efficient tap. 

Ketchup

As I understand it, there are two reasons for doing 4 ports instead of 3. One is to keep the system from being discovered by talking on the line. The second is you're trying to receive on all 4 wires in the cable.

If you could modify a nic to use all 4 wires as receive, and configure the os to handle that kind of nic, then I think it might be possible.

But I'm still just a noob.