You work in a company that accesses the Internet frequently. This makes the company's files susceptible to attacks from unauthorized access. You want to protect your company's network from external…

Gopher is a legacy document retrieval protocol with no security filtering capability and no role in protecting a network from external threats.

FTP is a file transfer protocol used to move files between systems and provides no mechanism to filter or block unauthorized network access.

HTTP is a stateless application-layer protocol for web communication and has no ability to enforce network perimeter security or block external attack traffic.

A firewall inspects incoming and outgoing network traffic against a configured ruleset, blocking unauthorized connection attempts from external sources such as the Internet - it is the primary perimeter defense mechanism designed specifically to protect internal networks from external attacks by controlling which traffic is allowed or denied.