A LAND Attack (Local Area Network Denial) is a type of Denial of Service (DoS) attack. In this attack, the attacker sends a specially crafted TCP SYN packet where the source and destination IP addresses and ports are set to be identical. This causes the target machine to repeatedly process the same packet, leading to a loop that can crash or freeze the system.
Example of a LAND Attack:
1. Attacker: Creates a TCP SYN packet with the source IP address and port set to the same values as the destination IP address and port.
2. Transmission: Sends this packet to the target machine.
3. Loop: The target machine receives the packet and attempts to reply to itself, entering an infinite loop.
4. Impact: The system’s resources are consumed, leading to a crash or freeze.
How a Firewall Protects Against LAND Attacks?
Firewalls can be configured to detect and block LAND attack packets. They do this by:
1. Packet Inspection: Analyzing incoming packets to check if the source and destination IP addresses and ports are the same.
2. Filtering: Dropping packets that match the criteria of a LAND attack, preventing them from reaching the target system.
3. Logging and Alerts: Recording instances of such packets and alerting administrators to potential attack attempts.
By implementing these measures, firewalls help protect networks from the disruptive effects of LAND attacks.