Which of the following protocols is a tunnel encryption used as a secure alternative to telnet?
Answer Description
Secure Shell, is a tunnel encryption using port 22. It is commonly used as a secure alternative to telnet. SSH can also be used to encrypt just about any plain-text protocol, for example FTP over SSH. Secure Socket Layer (SSL) and Transport Security Layer (TLS) are very similar to SSH but are most commonly used in HTTPS. Blowfish is an older, but still common symmetric-key block cipher.
Wikipedia
Secure Shell (SSH) is a cryptographic network protocol for operating network services securely over an unsecured network. Typical applications include remote command-line, login, and remote command execution, but any network service can be secured with SSH.
SSH provides a secure channel over an unsecured network in a client–server architecture, connecting an SSH client application with an SSH server. The protocol specification distinguishes between two major versions, referred to as SSH-1 and SSH-2. The standard TCP port …
Secure Shell - Wikipedia, the free encyclopedia