Firewalls act as security gates that control incoming and outgoing network traffic based on predetermined security rules. Logic gates are fundamental in designing these security rules. For example:

• AND Gate: A firewall might use an AND gate to allow traffic only if both conditions are met: the traffic is from a trusted IP address AND it matches an allowed port number1.

• OR Gate: An OR gate can be used to allow traffic if it meets at least one of several conditions, such as traffic from a trusted IP address OR traffic that matches a specific protocol1.

allowed_Ports = 80, 443, 22

IF packet.source IN IP_List AND packet.port IN allowed_ports THEN

ALLOW traffic

Logic gates enable the ALU to complete binary arithmetic and logical operations.

For example, the diagram above shows that when either pressure OR temperature exceed certain limits, the OR gate triggers a shutdown of the system to prevent malfunction.