Telnet
Telnet is a network protocol used for bidirectional interactive text-oriented communication over a TCP/IP network, typically on port 23. It allows users to remotely access and control another computer or network device through a command-line interface, enabling tasks like configuration, file transfer, and system administration. However, it transmits data in plaintext, making it insecure for modern use without additional security measures.
Developers should learn Telnet for legacy system maintenance, network troubleshooting, and understanding foundational remote access concepts, as it is still used in some embedded systems, routers, and older infrastructure. It is valuable for testing network services (e.g., SMTP, HTTP) by manually sending commands, but should be replaced with secure alternatives like SSH in production environments due to its lack of encryption.