A LAND (local area network denial) is a denial-of-service attack that consists of sending a special poison spoofed packet to a computer, causing it to lock up.
The attack involves sending a spoofed TCP SYN packet (connection initiation) with the target host's IP address to an open port as both source and destination.
Such systems had design flaws that would allow the device to accept request on the wire appearing to be from themselves, causing repeated replies.
Below is a list of vulnerable operating systems:[1] Most firewalls should intercept and discard the poison packet thus protecting the host from this attack.
Some operating systems released updates fixing this security hole.