How do You Find the IP Address of a Second Computer Directly Connected to the First One by Ethernet? | Dramel Notes

A broadcast IP ping might work. Not all systems answer to it, but some do when in 169.254 mode. Try ping 169.254.255.255 (needs -b on Linux), or ping ff02::1 (needs ping6 on Linux).

Directly sending a name lookup (using nbtstat -a) might work (if it runs Windows and if you know the computer’s name).

The 169.254 auto-configuration involves sending some ARP probes with the host’s own address (you can see those in Wireshark).

“Ethernet ping” exists, but only works at the Ethernet level. It will not tell you anything about the IP (It is sometimes implemented in the NIC itself, but mostly not implemented at all).

“Reverse ARP” also exists, but is almost never actually implemented either. Its primary use was superseded by BOOTP and later DHCP.