If you want to know how to find out someone's IP address, you can use the Facebook messenger/chat program to do so. You must first connect with the person; this connection should be open; thus, using Facebook's built-in chat feature is the ideal choice. After starting a chat session, keep it open while you launch the Command Prompt program or Utility tool. Enter netstat -an after starting this tool and pressing Enter. After a little delay, the end user's IP address should appear if you are still communicating with them.