Cisco IOS CLI

CLI vs GUI

• CLI (Command-Line Interface) – used to configure switches, routers, firewalls
• GUI (Graphical User Interface) – graphical configuration interface

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Connecting via Console Port

• There are 2 console ports on Catalyst 2960:
  • RJ45
  • USB Mini-B
• Rollover cable: RJ45 ↔ DB9 (serial port), called “rollover” because of the pinout:
  Pins: 1–8, 2–7, 3–6, 4–5, 5–4, 6–3, 7–2, 8–1
• Terminal emulator: e.g. PuTTY
  • Connection type: Serial
  • Should be connected to CLI
• Configure the serial line:
  • Speed (baud rate): 9600
  • Data bits: 8
  • Stop bits: 1
  • Parity: None
  • Flow control: None

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CLI Modes

• User EXEC Mode
  • Prompt: Router>
  • Very limited, cannot change configuration
  • “User mode” – usually not used for administrative tasks
• Privileged EXEC Mode
  • Prompt: Router#
  • Can view configuration, restart device
  • Not used to change configuration
• Global Configuration Mode
  • Prompt: Router(config)#
  • Used to make configuration changes

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Configuration Files

Two types:

• running-config – current, active configuration (can be edited via CLI)
• startup-config – will be loaded upon device restart

To save configuration:

write write memory copy running-config startup-config

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Password Encryption

Use enable secret instead of enable password (more secure)

service password-encryption

• Encrypts current and future passwords
• Does not affect the enable secret (already MD5-encrypted)

no service password-encryption

• Current and future passwords will not be encrypted
• enable secret remains unaffected

enable secret 5 xxx # Type 5: MD5 encryption enable password 7 xxx # Type 7: Cisco proprietary encryption

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Common CLI Commands

Router> enable //Enter privileged EXEC mode
Router# configure terminal //Enter global configuration mode
Router(config)# enable password //Set password for privileged EXEC mode
Router(config)# service password-encryption //Encrypt enable password
Router(config)# enable secret //Configure a secure, always-encrypted password
Router(config)# do show running-config //View current configuration
Router(config)# do show startup-config //View saved configuration
Router(config)# write //Save current configuration
Router(config)# no //Remove a command or setting
Router(config)# exit //Exit configuration mode

📌 These are personal study notes. Please read the full disclaimer for more information.