Security Configuration Guide, Cisco IOS XE Release 3SE (Cisco WLC 5700 Series)
Controlling Switch Access with Passwords and Privilege Levels
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Controlling Switch Access with Passwords and Privilege Levels

Contents

Controlling Switch Access with Passwords and Privilege Levels

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

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Restrictions for Controlling Switch Access with Passwords and Privileges

The following are the restrictions for controlling switch access with passwords and privileges:

  • Disabling password recovery will not work if you have set the switch to boot up manually by using the boot manual global configuration command. This command produces the boot loader prompt (switch:) after the switch is power cycled.
Related Concepts

Information About Passwords and Privilege Levels

Default Password and Privilege Level Configuration

A simple way of providing terminal access control in your network is to use passwords and assign privilege levels. Password protection restricts access to a network or network device. Privilege levels define what commands users can enter after they have logged into a network device.

This table shows the default password and privilege level configuration.

Table 1 Default Password and Privilege Levels

Feature

Default Setting

Enable password and privilege level

No password is defined. The default is level 15 (privileged EXEC level). The password is not encrypted in the configuration file.

Enable secret password and privilege level

No password is defined. The default is level 15 (privileged EXEC level). The password is encrypted before it is written to the configuration file.

Line password

No password is defined.

Additional Password Security

To provide an additional layer of security, particularly for passwords that cross the network or that are stored on a Trivial File Transfer Protocol (TFTP) server, you can use either the enable password or enable secret global configuration commands. Both commands accomplish the same thing; that is, you can establish an encrypted password that users must enter to access privileged EXEC mode (the default) or any privilege level you specify.

We recommend that you use the enable secret command because it uses an improved encryption algorithm.

If you configure the enable secret command, it takes precedence over the enable password command; the two commands cannot be in effect simultaneously.

If you enable password encryption, it applies to all passwords including username passwords, authentication key passwords, the privileged command password, and console and virtual terminal line passwords.

Password Recovery

By default, any end user with physical access to the switch can recover from a lost password by interrupting the boot process while the switch is powering on and then by entering a new password.

The password-recovery disable feature protects access to the switch password by disabling part of this functionality. When this feature is enabled, the end user can interrupt the boot process only by agreeing to set the system back to the default configuration. With password recovery disabled, you can still interrupt the boot process and change the password, but the configuration file (config.text) and the VLAN database file (vlan.dat) are deleted.

If you disable password recovery, we recommend that you keep a backup copy of the configuration file on a secure server in case the end user interrupts the boot process and sets the system back to default values. Do not keep a backup copy of the configuration file on the switch. If the switch is operating in VTP transparent mode, we recommend that you also keep a backup copy of the VLAN database file on a secure server. When the switch is returned to the default system configuration, you can download the saved files to the switch by using the Xmodem protocol.

To re-enable password recovery, use the service password-recovery global configuration command.

Terminal Line Telnet Configuration

When you power-up your switch for the first time, an automatic setup program runs to assign IP information and to create a default configuration for continued use. The setup program also prompts you to configure your switch for Telnet access through a password. If you did not configure this password during the setup program, you can configure it when you set a Telnet password for a terminal line. For more information on doing this, see Related Topics.

Username and Password Pairs

You can configure username and password pairs, which are locally stored on the switch. These pairs are assigned to lines or ports and authenticate each user before that user can access the switch. If you have defined privilege levels, you can also assign a specific privilege level (with associated rights and privileges) to each username and password pair.

Privilege Levels

Cisco switches (and other devices) use privilege levels to provide password security for different levels of switch operation. By default, the Cisco IOS software operates in two modes (privilege levels) of password security: user EXEC (Level 1) and privileged EXEC (Level 15). You can configure up to 16 hierarchical levels of commands for each mode. By configuring multiple passwords, you can allow different sets of users to have access to specified commands.

Privilege Levels on Lines

Users can override the privilege level you set using the privilege level line configuration command by logging in to the line and enabling a different privilege level. They can lower the privilege level by using the disable command. If users know the password to a higher privilege level, they can use that password to enable the higher privilege level. You might specify a high level or privilege level for your console line to restrict line usage.

For example, if you want many users to have access to the clear line command, you can assign it level 2 security and distribute the level 2 password fairly widely. But if you want more restricted access to the configure command, you can assign it level 3 security and distribute that password to a more restricted group of users.

Command Privilege Levels

When you set a command to a privilege level, all commands whose syntax is a subset of that command are also set to that level. For example, if you set the show ip traffic command to level 15, the show commands and show ip commands are automatically set to privilege level 15 unless you set them individually to different levels.

How to Control Switch Access with Passwords and Privilege Levels

Setting or Changing a Static Enable Password

The enable password controls access to the privileged EXEC mode. Beginning in privileged EXEC mode, follow these steps to set or change a static enable password:

SUMMARY STEPS

    1.    configure terminal

    2.    enable password password

    3.    end


DETAILED STEPS
     Command or ActionPurpose
    Step 1configure terminal


    Example:
    
    Controller# configure terminal
    
    
     

    Enters the global configuration mode.

     
    Step 2enable password password


    Example:
    Controller(config)# enable password secret321
    
    
     

    Defines a new password or changes an existing password for access to privileged EXEC mode.

    By default, no password is defined.

    For password, specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. It can contain the question mark (?) character if you precede the question mark with the key combination Crtl-v when you create the password; for example, to create the password abc?123, do this:

    Enter abc.

    Enter Crtl-v.

    Enter ?123.

    When the system prompts you to enter the enable password, you need not precede the question mark with the Ctrl-v; you can simply enter abc?123 at the password prompt.

     
    Step 3end


    Example:
    
    Controller(config)# end
    
    
     

    Returns to privileged EXEC mode.

     

    Protecting Enable and Enable Secret Passwords with Encryption

    Beginning in privileged EXEC mode, follow these steps to establish an encrypted password that users must enter to access privileged EXEC mode (the default) or any privilege level you specify:

    SUMMARY STEPS

      1.    configure terminal

      2.    Use one of the following:

      • enable password [ level level ] { password | encryption-type encrypted-password }
      • enable secret [ level level ] { password | encryption-type encrypted-password }

      3.    service password-encryption

      4.    end


    DETAILED STEPS
       Command or ActionPurpose
      Step 1configure terminal


      Example:
      
      Controller# configure terminal
      
      
       

      Enters the global configuration mode.

       
      Step 2Use one of the following:
      • enable password [ level level ] { password | encryption-type encrypted-password }
      • enable secret [ level level ] { password | encryption-type encrypted-password }


      Example:
      Controller(config)# enable password example102
      
      

      or

      Controller(config)# enable secret level 1 password secret123sample
      
      
       
      • Defines a new password or changes an existing password for access to privileged EXEC mode.
      • Defines a secret password, which is saved using a nonreversible encryption method.
        • (Optional) For level, the range is from 0 to 15. Level 1 is normal user EXEC mode privileges. The default level is 15 (privileged EXEC mode privileges).
        • For password, specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. By default, no password is defined.
        • (Optional) For encryption-type, only type 5, a Cisco proprietary encryption algorithm, is available. If you specify an encryption type, you must provide an encrypted password—an encrypted password that you copy from another switch configuration.
        Note   

        If you specify an encryption type and then enter a clear text password, you can not re-enter privileged EXEC mode. You cannot recover a lost encrypted password by any method.

       
      Step 3service password-encryption


      Example:
      Controller(config)# service password-encryption
      
      
      
       

      (Optional) Encrypts the password when the password is defined or when the configuration is written.

      Encryption prevents the password from being readable in the configuration file.

       
      Step 4end


      Example:
      
      Controller(config)# end
      
      
       

      Returns to privileged EXEC mode.

       

      Disabling Password Recovery

      Beginning in privileged EXEC mode, follow these steps to disable password recovery to protect the security of your switch:

      Before You Begin

      If you disable password recovery, we recommend that you keep a backup copy of the configuration file on a secure server in case the end user interrupts the boot process and sets the system back to default values. Do not keep a backup copy of the configuration file on the switch. If the switch is operating in VTP transparent mode, we recommend that you also keep a backup copy of the VLAN database file on a secure server. When the switch is returned to the default system configuration, you can download the saved files to the switch by using the Xmodem protocol.

      SUMMARY STEPS

        1.    configure terminal

        2.    no service password-recovery

        3.    end


      DETAILED STEPS
         Command or ActionPurpose
        Step 1configure terminal


        Example:
        
        Controller# configure terminal
        
        
         

        Enters the global configuration mode.

         
        Step 2no service password-recovery


        Example:
        Controller(config)# no service password-recovery
        
        
         

        Disables password recovery.

        This setting is saved in an area of the flash memory that is accessible by the boot loader and the Cisco IOS image, but it is not part of the file system and is not accessible by any user.

         
        Step 3end


        Example:
        
        Controller(config)# end
        
        
         

        Returns to privileged EXEC mode.

         
        What to Do Next

        To re-enable password recovery, use the service password-recovery global configuration command.

        Related Concepts

        Setting a Telnet Password for a Terminal Line

        Beginning in user EXEC mode, follow these steps to set a Telnet password for the connected terminal line:

        Before You Begin

        Attach a PC or workstation with emulation software to the switch console port, or attach a PC to the Ethernet management port.

        The default data characteristics of the console port are 9600, 8, 1, no parity. You might need to press the Return key several times to see the command-line prompt.

        SUMMARY STEPS

          1.    enable

          2.    configure terminal

          3.    line vty 0 15

          4.    password password

          5.    end


        DETAILED STEPS
           Command or ActionPurpose
          Step 1enable


          Example:
          Controller> enable
          
          
           
          Note   

          If a password is required for access to privileged EXEC mode, you will be prompted for it.

          Enters privileged EXEC mode.

           
          Step 2configure terminal


          Example:
          Controller# configure terminal
          
          
           

          Enters global configuration mode.

           
          Step 3line vty 0 15


          Example:
          Controller(config)# line vty 0 15
          
          
           

          Configures the number of Telnet sessions (lines), and enters line configuration mode.

          There are 16 possible sessions on a command-capable switch. The 0 and 15 mean that you are configuring all 16 possible Telnet sessions.

           
          Step 4password password


          Example:
          Controller(config-line)# password abcxyz543
          
          
           

          Sets a Telnet password for the line or lines.

          For password, specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. By default, no password is defined.

           
          Step 5end


          Example:
          Controller(config-line)# end
          
          
           

          Returns to privileged EXEC mode.

           

          Configuring Username and Password Pairs

          Beginning in privileged EXEC mode, follow these steps to configure username and password pairs:

          SUMMARY STEPS

            1.    configure terminal

            2.    username name [privilege level] {password encryption-type password}

            3.    Use one of the following:

            • line console 0
            • line vty 0 15

            4.    login local

            5.    end


          DETAILED STEPS
             Command or ActionPurpose
            Step 1configure terminal


            Example:
            
            Controller# configure terminal
            
            
             

            Enters the global configuration mode.

             
            Step 2username name [privilege level] {password encryption-type password}


            Example:
            Controller(config)# username adamsample privilege 1 password secret456
            
            
            Controller(config)# username 111111111111 mac attribute
             

            Sets the username, privilege level, and password for each user.

            • For name, specify the user ID as one word or the MAC address. Spaces and quotation marks are not allowed.
            • You can configure a maximum of 12000 clients each, for both username and MAC filter.
            • (Optional) For level, specify the privilege level the user has after gaining access. The range is 0 to 15. Level 15 gives privileged EXEC mode access. Level 1 gives user EXEC mode access.
            • For encryption-type, enter 0 to specify that an unencrypted password will follow. Enter 7 to specify that a hidden password will follow.
            • For password, specify the password the user must enter to gain access to the switch. The password must be from 1 to 25 characters, can contain embedded spaces, and must be the last option specified in the username command.
             
            Step 3Use one of the following:
            • line console 0
            • line vty 0 15


            Example:
            Controller(config)# line console 0
            
            

            or

            Controller(config)# line vty 15
            
             

            Enters line configuration mode, and configures the console port (line 0) or the VTY lines (line 0 to 15).

             
            Step 4login local


            Example:
            Controller(config-line)# login local
            
            
             

            Enables local password checking at login time. Authentication is based on the username specified in Step 2.

             
            Step 5end


            Example:
            
            Controller(config)# end
            
            
             

            Returns to privileged EXEC mode.

             

            Setting the Privilege Level for a Command

            Beginning in privileged EXEC mode, follow these steps to set the privilege level for a command:

            SUMMARY STEPS

              1.    configure terminal

              2.    privilege mode level level command

              3.    enable password level level password

              4.    end


            DETAILED STEPS
               Command or ActionPurpose
              Step 1configure terminal


              Example:
              
              Controller# configure terminal
              
              
               

              Enters the global configuration mode.

               
              Step 2privilege mode level level command


              Example:
              Controller(config)# privilege exec level 14 configure
              
              
               

              Sets the privilege level for a command.

              • For mode, enter configure for global configuration mode, exec for EXEC mode, interface for interface configuration mode, or line for line configuration mode.
              • For level, the range is from 0 to 15. Level 1 is for normal user EXEC mode privileges. Level 15 is the level of access permitted by the enable password.
              • For command, specify the command to which you want to restrict access.
               
              Step 3enable password level level password


              Example:
              Controller(config)# enable password level 14 SecretPswd14
              
              
               

              Specifies the password to enable the privilege level.

              • For level, the range is from 0 to 15. Level 1 is for normal user EXEC mode privileges.
              • For password, specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. By default, no password is defined.
               
              Step 4end


              Example:
              
              Controller(config)# end
              
              
               

              Returns to privileged EXEC mode.

               
              Related Information

              Changing the Default Privilege Level for Lines

              Beginning in privileged EXEC mode, follow these steps to change the default privilege level for the specified line:

              SUMMARY STEPS

                1.    configure terminal

                2.    line vty line

                3.    privilege level level

                4.    end


              DETAILED STEPS
                 Command or ActionPurpose
                Step 1configure terminal


                Example:
                
                Controller# configure terminal
                
                
                 

                Enters the global configuration mode.

                 
                Step 2line vty line


                Example:
                Controller(config)# line vty 10
                
                
                 

                Selects the virtual terminal line on which to restrict access.

                 
                Step 3privilege level level


                Example:
                Controller(config)# privilege level 15
                
                
                 

                Changes the default privilege level for the line.

                For level, the range is from 0 to 15. Level 1 is for normal user EXEC mode privileges. Level 15 is the level of access permitted by the enable password.

                 
                Step 4end


                Example:
                
                Controller(config)# end
                
                
                 

                Returns to privileged EXEC mode.

                 
                What to Do Next

                Users can override the privilege level you set using the privilege level line configuration command by logging in to the line and enabling a different privilege level. They can lower the privilege level by using the disable command. If users know the password to a higher privilege level, they can use that password to enable the higher privilege level. You might specify a high level or privilege level for your console line to restrict line usage.

                Related Information

                Logging into and Exiting a Privilege Level

                Beginning in user EXEC mode, follow these steps to log into a specified privilege level and exit a specified privilege level.

                SUMMARY STEPS

                  1.    enable level

                  2.    disable level


                DETAILED STEPS
                   Command or ActionPurpose
                  Step 1enable level


                  Example:
                  Controller> enable 15
                  
                  
                   

                  Logs in to a specified privilege level.

                  Following the example, Level 15 is privileged EXEC mode.

                  For level, the range is 0 to 15.

                   
                  Step 2disable level


                  Example:
                  Controller# disable 1
                  
                  
                   

                  Exits to a specified privilege level.

                  Following the example, Level 1 is user EXEC mode.

                  For level, the range is 0 to 15.

                   
                  Related Information

                  Monitoring Switch Access

                  Table 2 Commands for Displaying DHCP Information
                     

                  show privilege

                  Displays the privilege level configuration.

                  Configuration Examples for Setting Passwords and Privilege Levels

                  Example: Setting or Changing a Static Enable Password

                  This example shows how to change the enable password to l1u2c3k4y5. The password is not encrypted and provides access to level 15 (traditional privileged EXEC mode access):

                  Controller(config)# enable password l1u2c3k4y5
                  
                  

                  Example: Protecting Enable and Enable Secret Passwords with Encryption

                  This example shows how to configure the encrypted password $1$FaD0$Xyti5Rkls3LoyxzS8 for privilege level 2:

                  Controller(config)# enable secret level 2 5 $1$FaD0$Xyti5Rkls3LoyxzS8
                  
                  

                  Example: Setting a Telnet Password for a Terminal Line

                  This example shows how to set the Telnet password to let45me67in89:

                  Controller(config)# line vty 10
                  Controller(config-line)# password let45me67in89
                  
                  

                  Example: Setting the Privilege Level for a Command

                  This example shows how to set the configure command to privilege level 14 and define SecretPswd14 as the password users must enter to use level 14 commands:

                  Controller(config)# privilege exec level 14 configure
                  Controller(config)# enable password level 14 SecretPswd14
                  
                  
                  Related Information

                  Additional References

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