Cisco IOS CLI

CLI (Command-Line Interface) – used to configure switches, routers, and firewalls
GUI (Graphical User Interface)

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Connecting via Console Port

• There are 2 type of console ports: RJ45 and USB Mini-B
• Rollover cable: RJ45 <–> DB9 (serial port), called “rollover” because of pin mapping
• Pin mapping: 1–8, 2–7, 3–6, 4–5, 5–4, 6–3, 7–2, 8–1
• Terminal emulator: PuTTY (connection type: Serial → connects to CLI)
• Serial line configuration:
  • Speed (baud rate): 9600
  • Data bits: 8
  • Stop bits: 1
  • Parity: None
  • Flow control: None

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Modes

• Router> – User EXEC Mode (sign > ; Router is the hostname of the device), very limited (cannot change configuration), “user mode”, usually not used for tasks
• Router# – Privileged EXEC Mode (sign #), allows viewing configuration, restarting the device, saving config, but not editing it
• Router(config)# – Global Configuration Mode, used to change device configuration

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Apply Password

• enable password xxx → Type 7 (Cisco proprietary encryption)
• enable secret xxx → Type 5 (MD5 encryption)

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Password Encryption

• service password-encryption
  • Encrypts current and future passwords
  • Does not affect enable secret (already MD5)
• no service password-encryption
  • Leaves current and future passwords unencrypted
  • Does not affect enable secret

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Configuration Files

• running-config → current active configuration (editable in CLI)
• startup-config → loaded when the device restarts

Save Configuration:

• write == write memory == copy running-config startup-config
• Always use enable secret instead of enable password (more secure)

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Commands

Router> enable                       // enter Privileged EXEC mode
Router# configure terminal           // enter Global Configuration mode
Router(config)# enable password xxx  // set password for Privileged EXEC mode
Router(config)# service password-encryption // encrypts plain-text passwords
Router(config)# enable secret xxx    // set secure, always-encrypted password
Router(config)# do sh run            // executes a Privileged EXEC command from config mode
Router(config)# no <command>         // remove a command
Router(config)# do show running-config   // show current (running) config
Router(config)# do show startup-config   // show saved (startup) config
Router(config)# write                // save running-config to startup-config
Router(config)# exit                 // exit to previous mode

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