Design of remote Wake-up Software

Remote Wake-up (Wake-On-Lan, WOL) is a remote control technology that automatically starts the computer from the downtime state by sending specific data packets to the semi-working network card with the support of computer power supply, motherboard, network card and other devices.

The content of the remote wake-up packet is the FFFFFFFFFFFF plus the MAC address of the network card of the computer being awakened 16 times. The remote wake-up software broadcasts the data packet in the local area network using UDP. After the corresponding calculation is received, if the MAC in the packet matches the MAC of the network card, it sends a boot signal to the host.

The ARP protocol obtains the MAC address through IP and uses the SendARP function in C:\ WINDOWS\ SYSTEM32\ iphlpapi.dll (windows xp). Note that the MAC address returned by ARP is different from the actual address (if the returned MAC address is 00-11-22-33-44-55, it is actually 33-22-11-00-55-44).