Which protocol is primarily focused on enabling secure network access over the Internet?

The protocol that is primarily focused on enabling secure network access over the Internet is Secure Shell (SSH). SSH is a cryptographic network protocol designed to provide secure access to a computer or network service over an unsecured network. It does this by encrypting the connection to protect against eavesdropping, man-in-the-middle attacks, and other security threats. It is commonly used for secure remote administration of systems and secure file transfers.

While IPSec (the answer you provided) is indeed a protocol that secures Internet Protocol (IP) communications by encrypting and authenticating all packets at the IP layer, its primary use is in creating secure tunnels for VPNs (Virtual Private Networks). It is more about securing the transport of data between two points rather than enabling user-level secure access to a specific system or service.

In contrast, LDAP (Lightweight Directory Access Protocol) is meant for accessing and maintaining distributed directory information services over an Internet Protocol network. FTP (File Transfer Protocol) is used for transferring files but does not provide any inherent security measures. Therefore, SSH is the most suitable choice for secure network access.