Virtual teletype definition

Virtual teletype

(also VTY)

Virtual teletype (VTY) is a command line interface that gives users access to a device’s control plane, most often in network devices like routers and switches. By using it, administrators can configure, manage, and monitor the device remotely.

VTY lines are logical interfaces of a device. It means they don’t correspond to a physical port but are created in the device’s software. When a user connects to a device using a remote protocol, for example, SSH or Telnet, the device allocates a VTY line to that session. Each VTY line can accommodate one remote session at a time.

See also: command-line interface

Advantages of using VTY lines

VTY allows for remote configuration and monitoring of devices, so you don’t need physical access for management tasks.
Network devices support multiple VTY lines, which allows several administrators to manage the device simultaneously.
VTY sessions can be secured using authentication and encryption, especially when using protocols like SSH.

Disadvantages of using VTY lines

The number of VTY lines is finite. Once all lines are occupied, new sessions have to wait.
If not secured correctly, VTY can be an entry point for cybercriminals. This is a major concern when using older protocols like Telnet, which don’t encrypt data.
For beginners, CLI and VTY might have a steep learning curve compared to graphical interfaces.