The ‘line vty 0 15’ command in Cisco networking is used to configure and manage virtual terminal lines (VTY lines) on Cisco devices. VTY lines are software-based interfaces that allow administrators to establish a terminal session over a network connection to configure and manage the device remotely.
How to Use the ‘line vty 0 15’ Command:
- Enter the privileged EXEC mode on the Cisco device.
- Use the ‘line vty 0 15’ command to configure the VTY lines.
- Specify the range of VTY lines to be configured. In this case, the range is from 0 to 15, where 0 represents the first VTY line and 15 represents the last.
- Configure various parameters for the specified VTY lines, such as login authentication, access control, and terminal settings.
Functions of the ‘line vty 0 15’ Command:
- Login Authentication: The ‘line vty 0 15’ command allows you to configure login authentication methods for VTY lines. You can specify authentication methods such as username/password, TACACS+, or RADIUS.
- Access Control: You can use the ‘line vty 0 15’ command to control access to VTY lines based on various criteria, such as source IP address, username, or privilege level.
- Terminal Settings: The ‘line vty 0 15’ command enables you to configure terminal settings for VTY lines, such as terminal type, line speed, and flow control. These settings determine the characteristics of the terminal session, ensuring compatibility with different types of terminal devices.
Equipment Compatibility:
The ‘line vty 0 15’ command is supported on a wide range of Cisco networking devices, including routers, switches, and firewalls. However, the availability and specific functionality of the command may vary depending on the device model and operating system version. Refer to the Cisco documentation for the specific device you are using to obtain detailed information about the ‘line vty 0 15’ command.
line vty 0 15 Usage Examples
The ‘line vty 0 15’ command has the following examples:
- Changing the Password for Line vty 0 on a Cisco Router
conf t
Router>enable
Router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#line vty 0
Router(config-line)#password cisco123
Router(config-line)#end
Router(config)#
- Restricting Access to VTY Lines by IP Address:
conf t
Router(config)#line vty 0 15
Router(config-line)#login local
Router(config-line)#address 10.1.1.0 0.0.0.255
Router(config-line)#exit
In this example, access to VTY lines 0 through 15 is restricted to hosts with IP addresses in the range 10.1.1.0 to 10.1.1.255.
- Changing the Logging Level for a VTY Line:
Router(config)#line vty 0 4
Router(config-line)#logging synchronous
In this example, the logging level for VTY lines 0 through 4 is changed to synchronous, which means that all messages will be written to the log file immediately.
- Disabling a VTY Line:
Router(config)#line vty 5
Router(config-line)#shutdown
This command will disable VTY line 5, preventing users from accessing the router through that line.
- Changing the Default VTY Line Settings:
Router(config)#line vty
Router(config-line)#exec-timeout 0 0
Router(config-line)#privilege level 15
This command will change the default settings for all VTY lines. The ‘exec-timeout’ command sets the timeout for user inactivity to 0 minutes and 0 seconds, effectively disabling the timeout. The ‘privilege level 15’ command sets the default privilege level for users accessing the router through a VTY line to 15, which is the highest privilege level.
