Cisco CLI

There are various types of Cisco Networking devices used to connect different Networks using Cisco OS & CLI.

• Just like Windows OS which is the brain of the device where it is installed, Cisco's Operating System (OS) is 'Internet Operating System (IOS) which controls the Logic & Functions of Networking devices.

• And Just like Windows OS provides Command Prompt (CMD) which is a text based Interface where a user types the command & upon pressing the enter key it commands the Logic of that device which tells the device what to do, Command Line Interface (CLI) also does the same work.

• In return the Networking devices send a reply messages in CLI displaying the results.

• Cisco CLI can be accessed in 3 ways:

  1. Console Port,

  2. Telnet Access,

  3. SSH Access.

• Accessed CLI can be used in Three CLI Modes:

  1. User EXEC Mode/User Mode, 2. Enable Mode/Privileged Mode/Privileged EXEC mode, 3. Configure Terminal Mode.

• CLI's different Modes can be secured in Two ways:

  1. Using password only

  2. Using Username & Password

  3. Using External Authentication Servers

Reference:

CCNA 200-301 OCG, Volume 1, Pg. 87-88 - Wendell Odom.