Network Virtual Terminal
It is a set of principles describing a very simple virtual terminal interaction. The NVT is needed in the start of a Telnet session. Communication with the TCP/IP machine over the Ethernet network machine can be extended to more operations using Network Virtual Terminal instructions. It can be accessed according to the RFC2217 standard to modify baud rate on remote Virtual Serial Port. The simple NVT control instructions are added in the data packet with the character "FF" used as the instruction prefix. If the "FF" character happens within the normal data packet, it is generally doubled.