Answer:
Firewall.
Step-by-step explanation:
Firewall can be defined as a network security device that monitors incoming and outgoing network traffic and decides whether to allow or block specific traffic based on a defined set of security rules.
Simply stated, a firewall is a network security protocol that monitors and controls inbound and outbound traffic based on set aside security rules.
A firewall is used to control access to a computer or network, as it creates a barrier between a computer or a network and the internet in order to protect against unauthorized access.
Basically, it is a network security device or security system pre-installed on most computers to essentially inspect data being transmitted to or from a computer.
Hence, firewalls are typically bidirectional, it checks all sent and received data and only allow authorized traffic through.