Cisco line vty 0 - 4 Explanation and Configuration

cisco-line-vty-0-4-configuration-and-explanation

In this article, we will discuss the meaning of the Cisco line vty command. While working on Cisco Routers or Switches you may come across line vty configuration. So, In this article will explain the “line vty 0 4” and further, we will configure the line vty on Cisco Router. Let’s start!

Understanding line vty 0 4 configurations in Cisco Router/Switch

VTY stands for Virtual Teletype. I’m sure you already know the virtual interfaces, so the “vty” is a kind of virtual interface that is used to get CLI access to a Cisco Router or Switch over Telnet/SSH. All the connections are remotely over the network, so there is no hardware associated with it.

The command, line vty 0 4, will open 5 virtual interfaces, i.e. (0,1,2,3,4) for remote access. That means, 5 different administrators/connections can access the Cisco Router/Switch simultaneously using Telnet or SSH. Cisco hardware supports a maximum of 16 line virtual interfaces, i.e. (0,1,2,3,…,15).

line vty 0 4 configurations on Cisco Router / Switch

In this session, we will configure the line vty 0 4 configurations on Cisco Router. You must have proper privileges to access the device in configuration mode to configure the line vty configuration. Below configuration is the simple example of line vty configuration:

[simterm]GNS3_R1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
GNS3_R1(config)#line vty 0 4
GNS3_R1(config-line)#password cisco@123
GNS3_R1(config-line)#login
GNS3_R1(config-line)#exit[/simterm]

Note: You need to set enable password to get priviladed mode access!

At this point, I would like to explain one more command related to the remote access of the Cisco Router or Switch. This command is alternate to the line vty, but it will do the same task. That means, if you run the below command, it will open the line vty virtual port for you to gain access over the telnet or ssh. Below is a simple example of this configuration.

[simterm]GNS3_R1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
GNS3_R1(config)#aaa new-model[/simterm]

Here, the triple time a, i.e. AAA, stands for Authentication, Authorization, and Accounting. That means the default method of remote access is AAA. So, you will be not able to configure the line vty configuration further. If you want to switch back to the line vty configuration, you must remove the aaa configuration first. Below is the command to remove the aaa configuration.

[simterm]GNS3_R1(config)#no aaa new-model
Changing configuration back to no aaa new-model is not supported.
Continue?[confirm]
GNS3_R1(config)#[/simterm]

Once, you run the above command, it will remove all aaa-related configurations.

Summary

In this article, we discuss the command “live vty” and related configuration. vty stands for Virtual Teletype and is used to configure a virtual port to get the telnet or ssh access of the Cisco Router/Switch. Cisco hardware support up to 16 virtual port, i.e. (0,1,2,….15), on which administrators can telnet/ssh to gain remote access simultaneously. The command, line vty 0 4, will open 5 virtual ports, i.e. (0,1,2,..,5), which means only 5 administrators can log in to the device simultaneously.

The command, aaa new-model, will override the line vty configuration, and switch the remote authentication to the AAA.

I hope you like this article. I you have any challenge during the configuration, please comment in the comment box! Also, please share this article on social platforms to help us, it’s fee.