http://zqktlwk5ilgohy63eyrptyb4mc76bunfmxcnstkmveyjnskxkpq3b5yd.onion/wiki/Network_Attributes_Of_Your_Computer
Also, as part of the DHCP standard, all operating systems will provide their most recent IP address to the DHCP server. Usually this is harmless, since it is typically just an internal IP address, but if you use your laptop to DHCP directly to your ISP, it is possible it may then hand this IP to an open access point you associate to.