Which technology is used to create a secure connection over an unsecured network?

A Virtual Private Network (VPN) is a technology specifically designed to create a secure connection over an unsecured network, such as the internet. VPNs accomplish this by encrypting the data transmitted between the user's device and the VPN server, ensuring that sensitive information remains private and protected from eavesdropping or interception by unauthorized parties. This secure tunnel allows users to send and receive data as if they were directly connected to a private network, even when using a public or unsecured connection.

While Secure Socket Layer (SSL) is also associated with securing communications, it primarily operates at the level of specific applications (like web browsers), whereas a VPN establishes a broader secure environment for all internet traffic from the user's device. Firewalls serve as a barrier to control incoming and outgoing network traffic but do not create a secure tunnel for data transmission. Network Address Translation (NAT) is used for mapping private IP addresses to a public IP address, which aids in route networking but does not provide encryption or security for data over an unsecured network. Thus, the most fitting answer for creating a secure connection over an unsecured network is a VPN.