Firewall: A firewall is a device or software that controls access to a network by blocking unauthorized traffic.
VPN (Virtual Private Network): A VPN is a system that allows users to securely access a network over the Internet.
Encryption: Encryption is the process of converting plaintext into ciphertext to protect the confidentiality of data.
Access control: Access control is the process of controlling access to network resources based on user credentials.
Intrusion detection and prevention: Intrusion detection and prevention systems are used to detect and prevent unauthorized access to a network.