Access Method

CLI Access Methods of Networking Devices

All network devices require an operating system (OS). The portion of the OS that allows user to request for specific task is Shell. When using a command-line interface (CLI), the user interacts directly with the system in a text-based environment by entering commands on the keyboard at a command prompt.

A CLI session can be created with a networking device in two ways. One is Physical/Console, and another is Remote (SSH/Telnet).

Physical/Console Method:

To get access to a networking device such as router, you need a console cable (an RJ-45 connector on one end and a DB9 connector on the other to connect it to a computer's serial port or a USB-to-serial adapter.), terminal emulation program (putty, tera-term) installed in a pc.

Next, connect the RJ-45 connect end to the router’s console port (console port is a physical management port), and another end to the pc. Follow the attached picture below-

After that open the putty software> click on connection type serial> click on open as the picture shows below-

This is how a console method is used to access router CLI. This provides out-of-band access. Out-of-band access refers to access via a dedicated management channel that is used for device maintenance purposes only.

Serial Line COM1 is typically the first serial port detected by your system. When you connect a device to your computer using a serial cable the operating system assigns a COM port number to that connection. You can check your connection name from Device Manager of your pc.

Remote (SSH/Telnet) Method:

SSH/Telnet protocol requires to be configured on the router to remote access the router CLI. SSH/Telnet protocol provides an in-band method of remotely establishing a CLI session. The session is established via VTY port which is a virtual interface over the network.

SSH provides a secure connection whereas telnet does not provide a secure, encrypted connection and should only be used in a lab environment. User authentication, passwords, and commands are sent over the network in plaintext. The best practice is to use SSH instead of Telnet.

After configuring SSH open the putty software> click on connection type SSH>Input the IP address of the router> click on open as the picture shows below-