Firewall is a network security system, roughly divided into hardware firewall and software firewall, designed to monitor and control network traffic, according to predefined security rules to decide whether to allow the transmission of data packets. Its main function is to protect the internal network from external threats, prevent unauthorized access, and create a security barrier between the corporate network and the Internet. ‌ By filtering traffic, preventing malicious attacks, and recording network activities, firewalls improve network security and stability. As the first line of defense for network security, firewalls play a key role in the network environment of enterprises, institutions and individual users.