Which of the following is a secure way to connect to a device?

RSH (Remote Shell) transmits all data, including usernames and passwords, in cleartext over the network, making it vulnerable to packet sniffing and credential theft.

TFTP (Trivial File Transfer Protocol) provides no user authentication and no encryption whatsoever, transmitting all data in plaintext on UDP port 69.

SNMPv2 uses community strings (essentially plaintext passwords) for authentication and does not encrypt traffic, leaving management data and credentials exposed - SNMPv3 added security features like authentication and encryption.

SFTP (SSH File Transfer Protocol) runs over the SSH (Secure Shell) protocol, encrypting both the authentication credentials and all transferred data end-to-end. This encryption protects against eavesdropping and man-in-the-middle attacks, making it the accepted standard for secure file transfer.