Cisco Networking/CCENT/IOS Basics

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This lesson covers basic router and switch configuration using IOS commands.

Objectives and Skills[edit]

Objectives and skills for the IOS basics portion of Cisco CCENT certification include:[1]

  • Configure and verify utilizing the CLI to set basic Router configuration
    • Hostname
    • banner
    • motd
    • Local user & password
    • Enable secret password
    • Console logins
    • exec-timeout
    • service password encryption
    • copy run start

Readings[edit]

  1. Wikipedia: Cisco IOS
  2. Cisco: IOS and Configuration Basics
  3. Cisco: Using the Command-Line Interface in Cisco IOS Software
  4. Cisco: Telnet, Console and AUX Port Passwords on Cisco Routers Configuration Example

Multimedia[edit]

  1. YouTube: Cisco IOS CLI for Beginners - Part 1
  2. YouTube: Cisco IOS CLI for Beginners - Part 2
  3. YouTube: Cisco IOS CLI for Beginners - Part 3
  4. YouTube: Cisco IOS CLI for Beginners - Part 4
  5. YouTube: Cisco Router IOS - Command Line basics

Examples[edit]

Global Configuration[edit]

enable[edit]

To enter privileged EXEC mode, or any other security level set by a system administrator, use the enable EXEC command.[2]

enable

disable[edit]

To exit privileged EXEC mode and return to user EXEC mode, or to exit to a lower privilege level, enter the disable EXEC command.[3]

disable

configure terminal[edit]

To enter global configuration mode, use the configure terminal command in privileged EXEC mode.[4]

configure terminal

exit[edit]

To exit any configuration mode to the next highest mode in the CLI mode hierarchy, use the exit command in any configuration mode. To close an active terminal session by logging off the router, use the exit command in EXEC mode.[5][6]

exit

hostname[edit]

To specify or modify the hostname for the network server, use the hostname command in global configuration mode.[7]

hostname <name>

ip domain-name[edit]

To configure the domain name server (DNS) domain name, use the ip domain-name command in global configuration mode.[8]

ip domain-name <domain-name>

[edit]

To define and enable a customized banner to be displayed before the username and password login prompts, use the banner login global configuration command.[9]

banner login #<message>#

[edit]

To define and enable a message-of-the-day (MOTD) banner, use the banner motd global configuration command.[10]

banner motd #<message>#

Command Sequence[edit]

A global configuration command sequence to enable privileged EXEC mode, enter global configuration mode, specify a hostname and banner messages, exit global configuration mode, disable privileged EXEC mode, and log off the router is:

enable
configure terminal
hostname router
ip domain-name example.com
banner login #Authorized users only!#
banner motd #System maintenance will occur on Friday!#
exit
disable
exit

Password Configuration[edit]

line[edit]

To identify a specific line for configuration and enter line configuration collection mode, use the line command in global configuration mode.[11]

line console 0

password[edit]

To specify a password on a line, use the password command in line configuration mode.[12]

password <password>

login[edit]

To enable password checking at login, use the login command in line configuration mode.[13]

login

username[edit]

To establish a username-based authentication system, use the username command in global configuration mode.[14]

username <name> password <password>

login local[edit]

To enable username and password checking at login, use the login local command in line configuration mode.[15]

login local

exec-timeout[edit]

To set the interval that the EXEC command interpreter waits until user input is detected, use the exec-timeout line configuration command.[16]

exec-timeout <minutes>

enable password[edit]

To set a local clear-text password to control access to various privilege levels, use the enable password command in global configuration mode.[17]

enable password <password>

enable secret[edit]

To specify an additional layer of security over the enable password command, use the enable secret command in global configuration mode.[18]

enable secret <password>

service password-encryption[edit]

To encrypt passwords, use the service password-encryption command in global configuration mode.[19]

service password-encryption

Command Sequence[edit]

A command sequence to configure passwords might be similar to the following.

enable
configure terminal

line console 0
password letmein
login
exit

enable secret cisco
service password-encryption
exit

show running-config
exit

A command sequence to configure usernames and passwords might be similar to the following.

enable
configure terminal

username admin1 password secret1
username admin2 password secret2

line console 0
login local
exit

enable secret cisco
service password-encryption
exit

show running-config
exit

Configuration Management[edit]

show running-config[edit]

To display the contents of the current running configuration file or the configuration for a specific module, Layer 2 VLAN, class map, interface, map class, policy map, or virtual circuit (VC) class, use the show running-config command in privileged EXEC mode.[20]

show running-config
show run

show startup-config[edit]

The show startup-config command displays the startup configuration file contained in NVRAM or specified by the CONFIG_FILE environment variable.[21]

show startup-config
show start

copy[edit]

To copy any file from a source to a destination, use the copy command in privileged EXEC or diagnostic mode.[22]

copy <source> <destination>
copy running-config startup-config
copy run start

erase[edit]

To erase a file system or all files available on a file system, use the erase command in privileged EXEC or diagnostic mode.[23]

erase {/all nvram: | file-system: | startup-config}
erase startup-config

reload[edit]

To reload the operating system, use the reload command in privileged EXEC or diagnostic mode.[24]

reload

Command Sequence[edit]

A command sequence to manage device configuration might be similar to the following.

enable
show run
copy run start
show start
reload

Activities[edit]

  1. Connect to a Cisco router and practice using IOS commands.
    Cisco CCENT Router.png
    1. Review TechRepublic: 10 Commands You Should Master When Working with the Cisco IOS.
    2. Add a router to a new GNS3 project and start the device.
    3. Open the console for the router and practice using the following commands.
      • ?
      • show running-config
      • show interface
      • show ip interface
      • show ip interface brief
      • show ip route
      • show version
  2. Configure a router hostname, banner login, and banner motd messages.
    Cisco CCENT Router.png
    1. Add a router to a new GNS3 project and start the device.
    2. Open the console for the router and practice using the following commands.
      • enable
      • configure terminal
      • hostname
      • banner login
      • banner motd
      • exit
    3. Exit the router console session and open the console again to test the configuration.
  3. Configure router console password security.
    Cisco CCENT Router.png
    1. Add a router to a new GNS3 project and start the device.
    2. Open the console for the router and practice using the following commands.
      • enable
      • configure terminal
      • line console 0
      • password
      • login
      • exec-timeout
      • enable secret
      • service password-encryption
      • exit
    3. Verify the configuration using the following command.
      • show running-config
    4. Exit the router console session and open the console again to test the configuration.
  4. Configure router console username and password security.
    Cisco CCENT Router.png
    1. Add a router to a new GNS3 project and start the device.
    2. Open the console for the router and practice using the following commands.
      • enable
      • configure terminal
      • username
      • line console 0
      • login local
      • exec-timeout
      • enable secret
      • service password-encryption
      • exit
    3. Verify the configuration using the following command.
      • show running-config
    4. Exit the router console session and open the console again to test the configuration.
  5. Manage router configuration.
    Cisco CCENT Router.png
    1. Use one or more of the router configurations above and manage the configuration using the following commands.
      • enable
      • show running-config
      • copy running-config startup-config
      • show startup-config
      • reload
    2. After restarting the router, verify the configuration using the following command.
      • show running-config
    3. Clear the router configuration using the following commands.
      • erase startup-config
      • reload
    4. After restarting the router, verify the configuration using the following command.
      • show running-config

Lesson Summary[edit]

  • Cisco IOS (originally Internetwork Operating System) is software used on most Cisco Systems routers and network switches.[25]
  • IOS is a package of routing, switching, internetworking and telecommunications functions integrated into a multitasking operating system.[26]
  • Cisco IOS command modes determine the commands and privilege level of the current user.[27]
  • User EXEC mode allows connection to remote devices, changing terminal settings on a temporary basis, performing basic tests, and listing system information. User EXEC mode is indicated by a Router> prompt.[28]
  • Privileged EXEC mode allows all EXEC commands available on the system. Privileged EXEC mode is indicated by a Router# prompt.[29]
  • Global Configuration mode commands allow configuration of the system as a whole, and access to specific configuration modes and submodes. Global Configuration mode is indicated by a Router(config)# prompt.[30]
  • ROM Monitor mode is used for system diagnostics or when a valid system image is not found. ROM Monitor mode is indicated by a rommon1> prompt.[31]
  • Setup mode is an interactive sequence that allows first-time configuration of devices.[32]
  • More than 100 detail configuration modes and submodes are available for different interfaces and protocols.[33]
  • Almost every configuration command also has a no form used to disable the feature or function.[34]
  • Context-sensitive help is available by entering ? in any command mode.[35]
  • To enter privileged EXEC mode, or any other security level set by a system administrator, use the enable EXEC command.[36]
  • To exit privileged EXEC mode and return to user EXEC mode, or to exit to a lower privilege level, enter the disable EXEC command.[37]
  • To enter global configuration mode, use the configure terminal command in privileged EXEC mode.[38]
  • To exit any configuration mode to the next highest mode in the CLI mode hierarchy, use the exit command in any configuration mode.[39]
  • To close an active terminal session by logging off the router, use the exit command in EXEC mode.[40]
  • To specify or modify the hostname for the network server, use the hostname command in global configuration mode.[41]
  • To configure the domain name server (DNS) domain name, use the ip domain-name command in global configuration mode.[42]
  • To define and enable a customized banner to be displayed before the username and password login prompts, use the banner login global configuration command.[43]
  • To define and enable a message-of-the-day (MOTD) banner, use the banner motd global configuration command.[44]
  • To identify a specific line for configuration and enter line configuration collection mode, use the line command in global configuration mode.[45]
  • To specify a password on a line, use the password command in line configuration mode.[46]
  • To enable password checking at login, use the login command in line configuration mode.[47]
  • To establish a username-based authentication system, use the username command in global configuration mode.[48]
  • To enable username and password checking at login, use the login local command in line configuration mode.[49]
  • To set the interval that the EXEC command interpreter waits until user input is detected, use the exec-timeout line configuration command.[50]
  • To set a local clear-text password to control access to various privilege levels, use the enable password command in global configuration mode.[51]
  • To specify an additional layer of security over the enable password command, use the enable secret command in global configuration mode.[52]
  • To encrypt passwords, use the service password-encryption command in global configuration mode.[53]
  • To display the contents of the current running configuration file or the configuration for a specific module, Layer 2 VLAN, class map, interface, map class, policy map, or virtual circuit (VC) class, use the show running-config command in privileged EXEC mode.[54]
  • The show startup-config command displays the startup configuration file contained in NVRAM or specified by the CONFIG_FILE environment variable.[55]
  • To copy any file from a source to a destination, use the copy command in privileged EXEC or diagnostic mode.[56]
  • To erase a file system or all files available on a file system, use the erase command in privileged EXEC or diagnostic mode.[57]
  • To reload the operating system, use the reload command in privileged EXEC or diagnostic mode.[58]

Key Terms[edit]

command-line interface (CLI)
A means of interacting with a computer program where the user issues commands to the program in the form of successive lines of text.[59]
configuration mode
Allows commands that apply to the system as a whole, accessed using the configure command.[60]
console
The text entry and display interface for system administration messages.[61]
enable mode
Privileged EXEC mode, accessed using the enable command.[62]
host name
A label assigned to a device connected to a computer network and used to identify the device in various forms of electronic communication.[63]
IOS image
A Cisco system software file used to run Cisco routers and switches.[64]
local username
Usernames and passwords stored on the local device using the login local and username commands.[65]
running config file
The current system configuration, stored in RAM.[66]
startup config file
The current system boot configuration, stored in NVRAM.[67]
user mode
User EXEC mode, accessed by logging into a device.[68]

Review Questions[edit]

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Click on a question to see the answer.
  1. Cisco IOS (originally _____) is _____.
    Cisco IOS (originally Internetwork Operating System) is software used on most Cisco Systems routers and network switches.
  2. IOS is _____.
    IOS is a package of routing, switching, internetworking and telecommunications functions integrated into a multitasking operating system.
  3. Cisco IOS command modes _____.
    Cisco IOS command modes determine the commands and privilege level of the current user.
  4. User EXEC mode _____.
    User EXEC mode allows connection to remote devices, changing terminal settings on a temporary basis, performing basic tests, and listing system information.
  5. User EXEC mode is indicated by _____.
    User EXEC mode is indicated by a Router> prompt.
  6. Privileged EXEC mode _____.
    Privileged EXEC mode allows all EXEC commands available on the system.
  7. Privileged EXEC mode is indicated by _____.
    Privileged EXEC mode is indicated by a Router# prompt.
  8. Global Configuration mode commands _____.
    Global Configuration mode commands allow configuration of the system as a whole, and access to specific configuration modes and submodes.
  9. Global Configuration mode is indicated by _____.
    Global Configuration mode is indicated by a Router(config)# prompt.
  10. ROM Monitor mode is used for _____.
    ROM Monitor mode is used for system diagnostics or when a valid system image is not found.
  11. ROM Monitor mode is indicated by _____.
    ROM Monitor mode is indicated by a rommon1> prompt.
  12. Setup mode is _____.
    Setup mode is an interactive sequence that allows first-time configuration of devices.
  13. More than 100 detail configuration modes and submodes are available for _____.
    More than 100 detail configuration modes and submodes are available for different interfaces and protocols.
  14. Almost every configuration command also has _____ used to disable the feature or function.
    Almost every configuration command also has a no form used to disable the feature or function.
  15. Context-sensitive help is available by _____.
    Context-sensitive help is available by entering ? in any command mode.
  16. To enter privileged EXEC mode, or any other security level set by a system administrator, use _____.
    To enter privileged EXEC mode, or any other security level set by a system administrator, use the enable EXEC command.
  17. To exit privileged EXEC mode and return to user EXEC mode, or to exit to a lower privilege level, use _____.
    To exit privileged EXEC mode and return to user EXEC mode, or to exit to a lower privilege level, use the disable EXEC command.
  18. To enter global configuration mode, use _____.
    To enter global configuration mode, use the configure terminal command in privileged EXEC mode.
  19. To exit any configuration mode to the next highest mode in the CLI mode hierarchy, use _____.
    To exit any configuration mode to the next highest mode in the CLI mode hierarchy, use the exit command in any configuration mode.
  20. To close an active terminal session by logging off the router, use _____.
    To close an active terminal session by logging off the router, use the exit command in EXEC mode.
  21. To specify or modify the hostname for the network server, use _____.
    To specify or modify the hostname for the network server, use the hostname command in global configuration mode.
  22. To configure the domain name server (DNS) domain name, use _____.
    To configure the domain name server (DNS) domain name, use the ip domain-name command in global configuration mode.
  23. To define and enable a customized banner to be displayed before the username and password login prompts, use _____.
    To define and enable a customized banner to be displayed before the username and password login prompts, use the banner login global configuration command.
  24. To define and enable a message-of-the-day (MOTD) banner, use _____.
    To define and enable a message-of-the-day (MOTD) banner, use the banner motd global configuration command.
  25. To identify a specific line for configuration and enter line configuration collection mode, use _____.
    To identify a specific line for configuration and enter line configuration collection mode, use the line command in global configuration mode.
  26. To specify a password on a line, use _____.
    To specify a password on a line, use the password command in line configuration mode.
  27. To enable password checking at login, use _____.
    To enable password checking at login, use the login command in line configuration mode.
  28. To establish a username-based authentication system, use _____.
    To establish a username-based authentication system, use the username command in global configuration mode.
  29. To enable username and password checking at login, use _____.
    To enable username and password checking at login, use the login local command in line configuration mode.
  30. To set the interval that the EXEC command interpreter waits until user input is detected, use _____.
    To set the interval that the EXEC command interpreter waits until user input is detected, use the exec-timeout line configuration command.
  31. To set a local clear-text password to control access to various privilege levels, use _____.
    To set a local clear-text password to control access to various privilege levels, use the enable password command in global configuration mode.
  32. To specify an additional layer of security over the enable password command, use _____.
    To specify an additional layer of security over the enable password command, use the enable secret command in global configuration mode.
  33. To encrypt passwords, use _____.
    To encrypt passwords, use the service password-encryption command in global configuration mode.
  34. To display the contents of the current running configuration file or the configuration for a specific module, Layer 2 VLAN, class map, interface, map class, policy map, or virtual circuit (VC) class, use _____.
    To display the contents of the current running configuration file or the configuration for a specific module, Layer 2 VLAN, class map, interface, map class, policy map, or virtual circuit (VC) class, use the show running-config command in privileged EXEC mode.
  35. The show startup-config command _____.
    The show startup-config command displays the startup configuration file contained in NVRAM or specified by the CONFIG_FILE environment variable.
  36. To copy any file from a source to a destination, use _____.
    To copy any file from a source to a destination, use the copy command in privileged EXEC or diagnostic mode.
  37. To erase a file system or all files available on a file system, use _____.
    To erase a file system or all files available on a file system, use the erase command in privileged EXEC or diagnostic mode.
  38. To reload the operating system, use _____.
    To reload the operating system, use the reload command in privileged EXEC or diagnostic mode.

Assessments[edit]

See Also[edit]

References[edit]

Progress-1000.svg Completion status: this resource is considered to be complete.
  1. Cisco: ICND1 Exam Topics
  2. Cisco: Basic Command-Line Interface Commands
  3. Cisco: Basic Command-Line Interface Commands
  4. Cisco: IOS Configuration Fundamentals Command Reference
  5. Cisco: IOS Configuration Fundamentals Command Reference
  6. Cisco: IOS Configuration Fundamentals Command Reference
  7. Cisco: IOS Configuration Fundamentals Command Reference
  8. Cisco: Unity Express 2.0 Command Reference
  9. Cisco: IOS Configuration Fundamentals Command Reference
  10. Cisco: IOS Configuration Fundamentals Command Reference
  11. Cisco: Cisco IOS Terminal Services Command Reference
  12. Cisco: Passwords and Privileges
  13. Cisco IOS Terminal Services Command Reference
  14. Cisco: Passwords and Privileges Commands
  15. Cisco: Telnet, Console and AUX Port Passwords on Cisco Routers Configuration Example
  16. Cisco: IOS Configuration Fundamentals Command Reference
  17. Cisco: Passwords and Privileges Commands
  18. Cisco: Passwords and Privileges Commands
  19. Cisco: Passwords and Privileges Commands
  20. Cisco: IOS Configuration Fundamentals Command Reference
  21. Cisco: IOS Configuration Fundamentals Command Reference
  22. Cisco: IOS Configuration Fundamentals Command Reference
  23. Cisco: IOS Configuration Fundamentals Command Reference
  24. Cisco: IOS Configuration Fundamentals Command Reference
  25. Wikipedia: Cisco IOS
  26. Wikipedia: Cisco IOS
  27. Wikipedia: Cisco IOS
  28. Cisco: IOS Command Modes
  29. Cisco: IOS Command Modes
  30. Cisco: IOS Command Modes
  31. Cisco: IOS Command Modes
  32. Cisco: IOS Command Modes
  33. Cisco: IOS Command Modes
  34. Cisco: IOS and Configuration Basics
  35. Cisco: IOS and Configuration Basics
  36. Cisco: Basic Command-Line Interface Commands
  37. Cisco: Basic Command-Line Interface Commands
  38. Cisco: IOS Configuration Fundamentals Command Reference
  39. Cisco: IOS Configuration Fundamentals Command Reference
  40. Cisco: IOS Configuration Fundamentals Command Reference
  41. Cisco: IOS Configuration Fundamentals Command Reference
  42. Cisco: Unity Express 2.0 Command Reference
  43. Cisco: IOS Configuration Fundamentals Command Reference
  44. Cisco: IOS Configuration Fundamentals Command Reference
  45. Cisco: Cisco IOS Terminal Services Command Reference
  46. Cisco: Passwords and Privileges
  47. Cisco IOS Terminal Services Command Reference
  48. Cisco: Passwords and Privileges Commands
  49. Cisco: Telnet, Console and AUX Port Passwords on Cisco Routers Configuration Example
  50. Cisco: IOS Configuration Fundamentals Command Reference
  51. Cisco: Passwords and Privileges Commands
  52. Cisco: Passwords and Privileges Commands
  53. Cisco: Passwords and Privileges Commands
  54. Cisco: IOS Configuration Fundamentals Command Reference
  55. Cisco: IOS Configuration Fundamentals Command Reference
  56. Cisco: IOS Configuration Fundamentals Command Reference
  57. Cisco: IOS Configuration Fundamentals Command Reference
  58. Cisco: IOS Configuration Fundamentals Command Reference
  59. Wikipedia: Command-line interface
  60. Cisco: IOS Command Reference
  61. Wikipedia: System console
  62. Cisco: IOS Command Reference
  63. Wikipedia: Hostname
  64. Wikipedia: Cisco IOS
  65. Cisco: Telnet, Console and AUX Port Passwords on Cisco Routers Configuration Example
  66. Cisco: IOS and Configuration Basics
  67. Cisco: IOS and Configuration Basics
  68. Cisco: IOS and Configuration Basics