Suppose an attacker connects their computer with an Ethernet cable to a black box computer, which supports both TCP and UDP, over IPv4, over Ethernet. Direct connection, no switches in the loop.
The black box never initiates any communications. Its IP address is fixed.
Is there anything in these communication protocols which allows them to find out what IP address the box has, short of a brute force attack? Some binary equivalent of "Hey, what's your IP address?"? Or something more subtle, but still (ab)usable?