Security - IOS Usernames and Passwords

On a Cisco IOS device, there are several usernames and passwords that can be configured to provide various levels of access to the device. Here's an overview of the most common types of credentials used:

  1. Local Username and Password:

    • Purpose: These are used for individual user accounts. They allow users to log into the device with a unique username and password.
    • Configuration: They are configured locally on the device itself and are stored in the local username and password database.
    • Usage: When a user tries to access the device, they must enter their unique username and password. This is often used in conjunction with line passwords for VTY (Virtual Terminal Lines) for remote access like Telnet or SSH.
    • Example Command: username [username] privilege [level] secret [password].

  2. Enable Password:

    • Purpose: The enable password is used to grant privileged EXEC mode access from user EXEC mode.
    • Security Level: This is a less secure option as the password is stored in clear text in the device's configuration file.
    • Usage: After logging in, a user would enter the 'enable' command, followed by the enable password to access privileged EXEC mode.
    • Example Command: enable password [password].

  3. Enable Secret:

    • Purpose: Similar to the enable password, but it's a more secure version.
    • Security Level: It's encrypted and stored securely in the device's configuration.
    • Usage: Like the enable password, it's used to access privileged EXEC mode, but it overrides the enable password if both are set.
    • Example Command: enable secret [secret].

  4. Service Password-Encryption:

    • Purpose: Not a password itself, but a command to encrypt all plaintext passwords in the device's configuration.
    • Usage: It's used to add a layer of security to the device by ensuring that passwords are not easily readable in the configuration file.
    • Example Command: service password-encryption.

  5. Console Password:

    • Purpose: Used for securing physical access to the device via the console port.
    • Usage: When a user connects a computer directly to the device's console port, they must enter this password to gain user EXEC mode access.
    • Example Command: line console 0, followed by password [password] and login.
    • Note that if the login local command exists in the console configuration, the credentials from the local user database are used even if a console password is configured.

  6. VTY Passwords:

    • Purpose: Used for securing remote access to the device, such as via Telnet or SSH.
    • Usage: They are required to access the device remotely through a network.
    • Example Command: line vty 0 15, followed by password [password] and login.
    • Note that if the login local command exists in the VTY configuration, the credentials from the local user database are used even if a VTY password is configured.

  7. Auxiliary Password:

    • Purpose: Used for securing the auxiliary line, which is another means of physical access, often used for modem connections.
    • Usage: It's similar to the console password but for the auxiliary port.
    • Example Command: line aux 0, followed by password [password] and login.
    • Note that if the login local command exists in the AUX configuration, the credentials from the local user database are used even if a AUX password is configured.

Each of these passwords and access methods is designed to provide a layered security approach, ensuring that different levels of access are appropriately secured and that only authorized personnel can access specific functions of the Cisco IOS device.

It is possible to use more extensive AAA capabilities to further extend the methodology of gaining access to the CLI of such devices using RADIUS and TACACS+ services.

Links:

https://networklessons.com/cisco/ccna-routing-switching-icnd2-200-105/aaa-authentication-on-cisco-ios

https://forum.networklessons.com/t/aaa-authentication-on-cisco-ios/1558/79?u=lagapidis