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La question
Lecteur superutilisateur Melebius souhaite savoir comment trouver l'adresse IP d'un deuxième ordinateur directement connecté au premier par un câble Ethernet:
I have connected my primary computer to another one using a direct Ethernet cable connection. The second computer has no peripherals attached and I want to access it using RDP and SMB. The IP addresses are auto-configured, so it registers something in the range of 169.254.x.x.
I can wait until Windows recognizes the other computer or scan IP addresses, but both actions take a long and unpredictable amount of time. Is there a faster way to recognize the second computer at the other end of the Ethernet cable connection? I have considered making a broadcast “Ethernet ping” and reverse ARP, but I have been unable to find any instructions for this technique.
Comment trouvez-vous l'adresse IP d'un deuxième ordinateur directement connecté au premier par un câble Ethernet?
La réponse
Grawity, contributeur au superutilisateur, a la solution pour nous:
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 Its primary use was superseded by BOOTP and later DHCP.
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