Service Manual

A constrained RBAC model provides for separation of duty and as a result, provides greater security than the hierarchical RBAC
model. Essentially, a constrained model puts some limitations around each role’s permissions to allow you to partition of tasks.
However, some inheritance is possible.
Default command permissions are based on CLI mode (such as congure, interface, router), any specic command settings, and the
permissions allowed by the privilege and role commands. The role command allows you to change permissions based on the role. You
can modify the permissions specic to that command and/or command option. For more information, see Modifying Command
Permissions for Roles .
NOTE: When you enter a user role, you have already been authenticated and authorized. You do not need to enter an
enable password because you will be automatically placed in EXEC Priv mode.
For greater security, the ability to view event, audit, and security system log is associated with user roles. For information about
these topics, see Audit and Security Logs.
Privilege-or-Role Mode versus Role-only Mode
By default, the system provides access to commands determined by the user’s role or by the user’s privilege level. The user’s role
takes precedence over a user’s privilege level. If the system is in “privilege or role” mode, then all existing user IDs can continue to
access the switch even if they do not have a user role dened. To change to more secure mode, use role-based AAA authorization.
When role-based only AAA authorization is congured, access to commands is determined only by the user’s role. For more
information, see
Conguring Role-based Only AAA Authorization.
Conguring Role-based Only AAA Authorization
You can congure authorization so that access to commands is determined only by the user’s role. If the user has no user role,
access to the system is denied as the user will not be able to login successfully. When you enable role-based only AAA authorization
using the aaa authorization role-only command in Conguration mode, the Dell Networking OS checks to ensure that you do not
lock yourself out and that the user authentication is available for all terminal lines.
Pre-requisites
Before you enable role-based only AAA authorization:
1. Locally dene a system administrator user role. This will give you access to login with full permissions even if network
connectivity to remote authentication servers is not available.
2. Congure login authentication on the console. This ensures that all users are properly identied through authentication no
matter the access point.
If you do not congure login the authentication on the console, the system displays an error when you attempt to enable role-
based only AAA authorization.
3. Specify an authentication method list (RADIUS, TACACS+, or Local).
You must specify at least local authentication. For consistency, the best practice is to dene the same authentication method
list across all lines, in the same order of comparison; for example VTY and console port.
You could also use the default authentication method to apply to all the LINES (console port, VTY).
NOTE: The authentication method list should be in the same order as the authorization method list. For example, if
you congure the authentication method list in the following order (TACACS+, local), Dell Networking recommends
that authorization method list is congured in the same order (TACACS+, local).
4. Specify authorization method list (RADIUS, TACACS+, or Local). You must at least specify local authorization.
For consistency, the best practice is to dene the same authorization method list across all lines, in the same order of
comparison; for example VTY and console port.
You could also use the default authorization method list to apply to all the LINES (console port, VTY).
Security
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