Which port is normally required to be open for secure remote interactive shell access to Linux systems?

Port 443/tcp is used by HTTPS (HTTP Secure) for encrypted web traffic, not for secure remote shell access.

Port 23/tcp is used by Telnet, which provides remote shell access but is considered insecure because it transmits data, including authentication credentials, in plaintext.

Port 22/tcp is the default and well-known port for the Secure Shell (SSH) protocol, which provides encrypted and secure remote command-line access, file transfer, and other network services over an unsecured network to Linux systems.

Port 25/tcp is designated for SMTP (Simple Mail Transfer Protocol), which is used for sending email, not for remote interactive shell access.