Configuring User Accounts and RBAC

This chapter contains the following sections:

Information About User Accounts and RBAC

Cisco Nexus Series switches use role-based access control (RBAC) to define the amount of access that each user has when the user logs into the switch.

With RBAC, you define one or more user roles and then specify which management operations each user role is allowed to perform. When you create a user account for the switch, you associate that account with a user role, which then determines what the individual user is allowed to do on the switch.

User Account Configuration Restrictions

The following words are reserved and cannot be used to configure users:

  • adm

  • bin

  • daemon

  • ftp

  • ftpuser

  • games

  • gdm

  • gopher

  • halt

  • lp

  • mail

  • mailnull

  • man

  • mtsuser

  • news

  • nobody

  • shutdown

  • sync

  • sys

  • uucp

  • xfs

User Password Requirements

Cisco Nexus 3000 Series passwords are case sensitive can contain alphanumeric characters only. Special characters, such as the dollar sign ($) or the percent sign (%), are not allowed.

If a password is trivial (such as a short, easy-to-decipher password), the Cisco Nexus 3000 Series switch rejects the password. Be sure to configure a strong password for each user account. A strong password has the following characteristics:

  • At least eight characters long

  • Does not contain many consecutive characters (such as "abcd")

  • Does not contain many repeating characters (such as "aaabbb")

  • Does not contain dictionary words

  • Does not contain proper names

  • Contains both uppercase and lowercase characters

  • Contains numbers

The following are examples of strong passwords:

  • If2CoM18

  • 2009AsdfLkj30

  • Cb1955S21


Note

For security reasons, user passwords do not display in the configuration files.

User Roles

User roles contain rules that define the operations allowed for the user who is assigned the role. Each user role can contain multiple rules and each user can have multiple roles. For example, if role1 allows access only to configuration operations, and role2 allows access only to debug operations, users who belong to both role1 and role2 can access configuration and debug operations. You can also limit access to specific VSANs, VLANs, and interfaces.

The Cisco Nexus 3000 Series switch provides the following default user roles:

  • network-admin (superuser)—Complete read and write access to the entire switch.

  • network-operator—Complete read access to the switch.


Note

If you belong to multiple roles, you can execute a combination of all the commands permitted by these roles. Access to a command takes priority over being denied access to a command. For example, suppose a user has RoleA, which denied access to the configuration commands. However, the user also has RoleB, which has access to the configuration commands. In this case, the user has access to the configuration commands.

Rules

The rule is the basic element of a role. A rule defines what operations the role allows the user to perform. You can apply rules for the following parameters:

  • Command—A command or group of commands defined in a regular expression.

  • Feature—Commands that apply to a function provided by the Cisco Nexus 3000 Series switch.

    • Enter the show role feature command to display the feature names available for this parameter.

  • Feature group—Default or user-defined group of features.

    • Enter the show role feature-group command to display the default feature groups available for this parameter.

These parameters create a hierarchical relationship. The most basic control parameter is the command. The next control parameter is the feature, which represents all commands associated with the feature. The last control parameter is the feature group. The feature group combines related features and allows you to easily manage the rules.

You can configure up to 256 rules for each role. The user-specified rule number determines the order in which the rules are applied. Rules are applied in descending order. For example, if a role has three rules, rule 3 is applied before rule 2, which is applied before rule 1.

User Role Policies

You can define user role policies to limit the switch resources that the user can access. You can define user role policies to limit access to interfaces, VLANs, and VSANs.

User role policies are constrained by the rules defined for the role. For example, if you define an interface policy to permit access to specific interfaces, the user does not have access to the interfaces unless you configure a command rule for the role to permit the interface command.

If a command rule permits access to specific resources (interfaces, VLANs, or VSANs), the user is permitted to access these resources, even if the user is not listed in the user role policies associated with that user.

Guidelines and Limitations for User Accounts

User account and RBAC have the following configuration guidelines and limitations:

  • You can add up to 256 rules to a user role.

  • You can assign a maximum of 64 user roles to a user account.


Note

A user account must have at least one user role.

Configuring User Accounts

You can create a maximum of 256 user accounts on a Cisco Nexus Series switch. User accounts have the following attributes:

  • Username

  • Password

  • Expiry date

  • User roles

User accounts can have a maximum of 64 user roles.


Note

Changes to user account attributes do not take effect until the user logs in and creates a new session.

Procedure
     Command or ActionPurpose
    Step 1 switch(config)# show role
          		(Optional)

    Displays the user roles available. You can configure other user roles, if necessary.

     
    Step 2 switch# configure terminal
     

    Enters configuration mode.

     
    Step 3 switch(config)# username user-id [password password] [expire date] [role role-name]
     

    Configures a user account. The user-id is a case-sensitive, alphanumeric character string with a maximum of 28 characters.

    The default password is undefined.

    Note   

    If you do not specify a password, the user might not be able to log in to the Cisco Nexus 3000 Series switch.

    The expire date option format is YYYY-MM-DD. The default is no expiry date.

     
    Step 4 switch# show user-account
          		(Optional)

    Displays the role configuration.

     
    Step 5 switch# copy running-config startup-config
          		(Optional)

    Copies the running configuration to the startup configuration.

     

    The following example shows how to configure a user account: 

    switch# configure terminal

    switch(config)# username NewUser password 4Ty18Rnt


    switch(config)# exit

    switch# show user-account

    Configuring RBAC

    Creating User Roles and Rules

    Each user role can have up to 256 rules. You can assign a user role to more that one user account.

    The rule number that you specify determines the order in which the rules are applied. Rules are applied in descending order. For example, if a role has three rules, rule 3 is applied before rule 2, which is applied before rule 1.

    Procedure
       Command or ActionPurpose
      Step 1 switch# configure terminal
       

      Enters configuration mode.

       
      Step 2 switch(config)# role name role-name
       

      Specifies a user role and enters role configuration mode. The role-name argument is a case-sensitive, alphanumeric character string with a maximum of 16 characters.

       
      Step 3 switch(config-role)# rule number {deny | permit} command command-string
       

      Configures a command rule.

      The command-string can contain spaces and regular expressions. For example, interface ethernet * includes all Ethernet interfaces.

      Repeat this command for as many rules as needed.

       
      Step 4 switch(config-role)# rule number {deny | permit} {read | read-write}
       

      Configures a read-only or read-and-write rule for all operations.

       
      Step 5 switch(config-role)# rule number {deny | permit} {read | read-write} feature feature-name
       

      Configures a read-only or read-and-write rule for a feature.

      Use the show role feature command to display a list of features.

      Repeat this command for as many rules as needed.

       
      Step 6 switch(config-role)# rule number {deny | permit} {read | read-write} feature-group group-name
       

      Configures a read-only or read-and-write rule for a feature group.

      Use the show role feature-group command to display a list of feature groups.

      Repeat this command for as many rules as needed.

       
      Step 7 switch(config-role)# description text
              		(Optional)

      Configures the role description. You can include spaces in the description.

       
      Step 8 switch# show role
              		(Optional)

      Displays the user role configuration.

       
      Step 9 switch# copy running-config startup-config
              		(Optional)

      Copies the running configuration to the startup configuration.

       

      The following example shows how to create user roles and specify rules: 

      switch# configure terminal

      switch(config)# role name UserA

      switch(config-role)# rule deny command clear users

      switch(config-role)# rule deny read-write

      switch(config-role)# description This role does not allow users to use clear commands

      switch(config-role)# end

      switch(config)# show role

      Creating Feature Groups

      You can create feature groups.

      Procedure
         Command or ActionPurpose
        Step 1 switch# configure terminal
         

        Enters configuration mode.

         
        Step 2 switch(config)# role feature-group group-name
         

        Specifies a user role feature group and enters role feature group configuration mode.

        The group-name is a case-sensitive, alphanumeric character string with a maximum of 32 characters.

         
        Step 3 switch# show role feature-group
                  		(Optional)

        Displays the role feature group configuration.

         
        Step 4 switch# copy running-config startup-config
                  		(Optional)

        Copies the running configuration to the startup configuration.

         

        Changing User Role Interface Policies

        You can change a user role interface policy to limit the interfaces that the user can access.

        Procedure
           Command or ActionPurpose
          Step 1 switch# configure terminal
           

          Enters configuration mode.

           
          Step 2 switch(config)# role name role-name
           

          Specifies a user role and enters role configuration mode.

           
          Step 3 switch(config-role)# interface policy deny
           

          Enters role interface policy configuration mode.

           
          Step 4 switch(config-role-interface)# permit interface interface-list
           

          Specifies a list of interfaces that the role can access.

          Repeat this command for as many interfaces as needed.

          For this command, you can specify Ethernet interfaces, Fibre Channel interfaces, and virtual Fibre Channel interfaces.

           
          Step 5 switch(config-role-interface)# exit
           

          Exits role interface policy configuration mode.

           
          Step 6 switch(config-role)# show role
                      		(Optional)

          Displays the role configuration.

           
          Step 7 switch(config-role)# copy running-config startup-config
                      		(Optional)

          Copies the running configuration to the startup configuration.

           

          The following example shows how to change a user role interface policy to limit the interfaces that the user can access: 

          switch# configure terminal

          switch(config)# role name UserB

          switch(config-role)# interface policy deny

          switch(config-role-interface)# permit interface ethernet 2/1

          switch(config-role-interface)# permit interface fc 3/1

          switch(config-role-interface)# permit interface vfc 30/1

          You can specify a list of interfaces that the role can access. You can specify it for as many interfaces as needed.

          Changing User Role VLAN Policies

          You can change a user role VLAN policy to limit the VLANs that the user can access.

          Procedure
             Command or ActionPurpose
            Step 1 switch# configure terminal
             

            Enters configuration mode.

             
            Step 2 switch(config)# role name role-name
             

            Specifies a user role and enters role configuration mode.

             
            Step 3 switch(config-role)# vlan policy deny
             

            Enters role VLAN policy configuration mode.

             
            Step 4 switch(config-role-vlan)# permit vlan vlan-list
             

            Specifies a range of VLANs that the role can access.

            Repeat this command for as many VLANs as needed.

             
            Step 5 switch# show role
                          		(Optional)

            Displays the role configuration.

             
            Step 6 switch# copy running-config startup-config
                          		(Optional)

            Copies the running configuration to the startup configuration.

             

            Verifying the User Accounts and RBAC Configuration

            To display user account and RBAC configuration information, perform one of the following tasks:

            Command

            Purpose

            show role

            Displays the user role configuration

            show role feature

            Displays the feature list.

            show role feature-group

            Displays the feature group configuration.

            show startup-config security

            Displays the user account configuration in the startup configuration.

            show running-config security [all]

            Displays the user account configuration in the running configuration. The all keyword displays the default values for the user accounts.

            show user-account

            Displays user account information.

            Configuring User Accounts Default Settings for the User Accounts and RBAC

            The following table lists the default settings for user accounts and RBAC parameters.

            Table 1  Default User Accounts and RBAC Parameters

            Parameters

            Default

            User account password

            Undefined.

            User account expiry date

            None.

            Interface policy

            All interfaces are accessible.

            VLAN policy

            All VLANs are accessible.

            VFC policy

            All VFCs are accessible.

            VETH policy

            All VETHs are accessible.