On Windows, how do you stop the monitoring host from generating packets?

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I want to capture the traffic between a device and a router. I have placed a hub between the two to which I can attach the monitoring host. Wireshark is installed on an XP computer to do the monitoring.

My problem is that as soon as I attach the XP computer it generates lots of packets that are interfering with the device I'm trying to monitor. I know I can filter all the XP packets, but I want to do the monitoring without generating them in the first place.

How can I configure the XP host / Wireshark to monitor without generating its own packets?