The "LAND attack" is a network attack dating from 1997 using IP address spoofing to exploit a flaw on some TCP/IP protocol implementations in systems. The name of this attack comes from the name given to the first distributed source code (called "exploit") that made it possible to implement this attack: land.c.
The LAND attack therefore involves sending a packet with the same IP address and the same port number in the source and destination fields of IP packets.
Directed against vulnerable systems, this attack caused systems to lock up or become unstable.
Recent systems are no longer vulnerable to this type of attack.