2. The username and encrypted password are sent over the network to the RADIUS server. 3. The user receives one of the following responses from the RADIUS server: • ACCEPT: The user is authenticated. • REJECT: The user is either not authenticated and is prompted to re-enter the username and password, or access is denied. • CHALLENGE: A challenge requires additional data from the user. • CHALLENGE PASSWORD: A response requests the user to select a new password. The ACCEPT or REJECT response is bundled with additional data that is used for privileged EXEC or network authorization. The additional data included with the ACCEPT or REJECT packets includes these items:
• Telnet, SSH, rlogin, or privileged EXEC services • Connection parameters, including the host or client IP address, access list, and user timeouts RADIUS Change of Authorization The RADIUS Change of Authorization (CoA) provides a mechanism to change the attributes of an authentication, authorization, and accounting (AAA) session after it is authenticated. When a policy changes for a user or user group in AAA, administrators can send RADIUS CoA packets from the AAA server such as a Cisco Secure Access Control Server (ACS) to reinitialize authentication and apply the new policy.
This section provides an overview of the RADIUS interface including available primitives and how they are used during a CoA. • Change-of-Authorization Requests • CoA Request Response Code • CoA Request Commands • Session Reauthentication • Stacking Guidelines for Session Termination A standard RADIUS interface is typically used in a pulled model where the request originates from a network attached device and the response come from the queried servers. Cisco devices support the RADIUS CoA extensions defined in RFC 5176 that are typically used in a pushed model and allow for the dynamic reconfiguring of sessions from external AAA or policy servers.
Cisco devices supports these per-session CoA requests: • Session reauthentication • Session termination • Session termination with port shutdown • Session termination with port bounce This feature is integrated with Cisco Secure Access Control Server (ACS) 5.1. Configuring RADIUS RADIUS Change of Authorization Configuring RADIUS 4