What port does the sshd daemon listen on by default for incoming SSH connections?

The Secure Shell (SSH) daemon, commonly referred to as sshd, is designed to provide a secure channel over an unsecured network for remote administration and file transfers. By default, sshd listens for incoming connections on port 22. This port has been designated for SSH in the Internet Assigned Numbers Authority (IANA) Service Name and Transport Protocol Port Number Registry.

Using port 22 allows clients to securely connect to servers running sshd without needing to specify a different port number, simplifying the connection process. This standardization across deployments promotes better interoperability and consistency among different systems and SSH clients.

The other options represent ports allocated for different protocols: port 21 is used for FTP (File Transfer Protocol), port 23 is associated with Telnet (an older protocol for unencrypted communication), and port 80 is the standard port for HTTP (Hypertext Transfer Protocol) traffic on the web. Thus, selecting port 22 recognizes its special role as the default port for SSH connections.