Definition of VTY (2024)

FAQs

What does VTY mean? ›

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.

TTY is a physically connected one, via the serial/console port. VTY is a virtually connected one, via telnet or SSH.

vty is the virtual terminal, or telnet. There are 16 total vty sessions available. The numbers represent each session, so vty 5 15 means you are configuring vty sessions 5 through 15.

VTY is solely used for inbound connections to the device. These connections are all virtual with no hardware associated with them. Here's a breakdown of key points related to “line vty”: Purpose: It allows network administrators to connect to and manage Cisco devices remotely.

The virtual terminal or “VTY” lines are virtual lines that allow connecting to the device using telnet or Secure Shell (SSH). Cisco devices can have up to 16 VTY lines. You can determine how many VTY lines you have by issuing “line vty 0 ?” from global configuration mode.

Passwords on VTY lines are used to control access to the router itself. By default, it only provides non-privileged access, so you can't change any configuration.

Second, by default Telnet is associated with the VTY lines. Telnet uses TCP port number 23 and is one of the most commonly used protocols for remote access. However, telnet doesn't have any type of confidentiality. In other words, it has no encryption mechanism.

It defines how many VTY's that are active on the device and essentially how many simultaneous remote connections you want to allow/support. In case of "line vty 0 4", you can have five simultaneous connections.

console 0 is the physical console port on the switch/router you plug into. line vty is when you remote into the switch/router via telnet or ssh. the config-line is letting you know you are currently in configuration mode for that specific line. Some commands are also different in relation to them.

If you use telnet or SSH to access the switch they are accessing the vty lines and use the password configured on the vty. You need 2 passwords because there are 2 different ways to access the switch. While it is common to use the same password for both console and vty there is no requirement that they be the same.

How many VTY lines are on a router? ›

By default all routers have 5 vty lines (factory defaults). Unless you configure the remaining available lines, there is no need for them to be protected.

VTY lines are usually used for creating out-of-band management sessions to devices. If a password is not supplied on a vty line, that line cannot be used for managing the device. In some cases administrators may decide to let junior staff to use lines 0 - 4 and senior staff to use lines 5 - 15.

A VTY line is used for SSH and Telnet access to the device. Here you configure login parameters and password. A VLAN interface is in simplest terms the Layer 3 interface for a VLAN, allowing you to configure an IP address on it.

vty: Specifies the VTY line. first-number2: Specifies the relative number of the first user line. The value range is 0 to 7 for AUX lines and 0 to 63 for VTY lines.

The Virtual Type Terminal (VTY) manages and monitors users who log in to the device using VTY user interfaces. When a user's terminal connects to the device using Telnet or Secure Shell (SSH), a VTY is set up.

Virtual terminals are logical connections from the network to the router; these are typically telnet or rlogin connections. When a user telnets to a router from the network, as in Figure 4-2, the router starts an EXEC process to handle this connection.