014.06.16.3. How does TELNET differentiate between local and remote logins, and what are the implications of each for system security and resource access?
Whenever a user logs in into a local timesharing system, it is referred to as local login, whereas when the user wants to access the resources or utilities on the remote machine, it is referred to as remote login. There are no impilication for sytem security and access on TELNET.
Local log-in: When a user logs into a local system and inputs their credentials at the terminal, the terminal driver forwards the characters to the operating system. The operating system interprets the character sequence and then invokes the application program.
Remote log-in: When a user logs into a remote system using TELNET and enters credentials at their local terminal, the local operating system does not interpret the characters. Instead, the characters are transmitted as-is to the TELNET client running on the user's local machine. This TELNET client is responsible for translating the characters into the universal character set known as Network Virtual Terminal (NVT) characters. Subsequently, the NVT-formatted text travels through the internet, reaching the TCP/IP protocol stack on the remote machine. The characters are then forwarded to the TELNET server on the remote system, which ultimately converts them into corresponding characters, verifies credentials, and grants access.
