Enterasys Networks 9034385 manual Identify the Strategic Point for End-System Authorization

Survey the Network

authenticated to the network and interact with Enterasys NAC for authentication, assessment, authorization, and remediation. Note however, that this configuration may not be possible if trusted users are also being MAC authenticated to the network in the same Security Domain. In this case, MAC or user overrides would need to be configured for the trusted users, and the default NAC configuration of the Security Domain would specify the NAC implementation for guest users.

•If guest access is implemented with web‐based authentication using the guest networking feature on Enterasys policy‐capable switches (supplying default credentials in the web login page for guest users), the guest networking feature must be configured to send the default credentials to a backend RADIUS server and not locally authenticate them. This is because in the out‐of‐band NAC configuration, the NAC Gateway must receive the authentication attempt via RADIUS in order to detect the connecting end‐systems. A RADIUS server with the guest networking credentials must be deployed on the network so the NAC Gateway can proxy the RADIUS requests to the upstream RADIUS server. If a RADIUS Filter‐ID or VLAN Tunnel attribute is not configured for the guest networking credentials on the upstream RADIUS server, Enterasys NAC can be configured to include a Filter‐ID or VLAN Tunnel attribute in the RADIUS Access‐Accept packet returned to the switch by implementing a user override for the guest networking username.

3.Identify the Strategic Point for End-System Authorization

In this step, you will identify the strategic point in the network where end‐system authorization should be implemented.

The most secure place for implementing authorization is directly at the point of connection at the edge of the network, as supported by Enterasys policy‐capable switches. In this configuration, the implementation of out‐of‐band NAC using the NAC Gateway appliance leverages policy on Enterasys switches to securely authorize connecting end‐systems.

RFC 3580‐capable switches can be used for authentication and authorization by assigning end‐ systems to particular VLANs based on the authentication and assessment results. However, this is not as secure as using Enterasys policy‐capable switches, for the two following reasons:

•VLANs authorize end‐systems by placing them into the same container, with the traffic enforcement point implemented at the ingress/egress point to the VLAN on the VLANʹs routed interface. Because authorization is not implemented between end‐systems within the same VLAN, an end‐system in a VLAN is open to launch attacks or be attacked by other devices within the same VLAN. For example, if end‐system A with virus X and end‐system B with virus Y are quarantined into the same VLAN, then end‐system A and B may become infected with virus X and Y. Enterasys policy uniquely authorizes connecting end‐systems independent of their VLAN assignment by permitting, denying, and prioritizing traffic on ingress to the network at the port level.

•Because RFC 3580‐capable switches implement the traffic enforcement point for a VLAN at the VLAN’s routed interface, malicious traffic is allowed onto the network and may consume bandwidth, memory, and CPU cycles on infrastructure devices before being discarded possibly several hops deep within the network. This is especially detrimental to the operation of the network if a single inter‐switch link connecting the access layer to distribution layer is used to transmit traffic from both the quarantine VLAN and the production VLAN (such as an 802.1Q VLAN trunked link). Traffic from quarantined end‐systems (for example, worms scanning for vulnerable hosts) can consume the entire bandwidth available on the inter‐switch link and affect network connectivity for end‐systems on the production VLAN. In contrast, since the traffic enforcement point for Enterasys policy is at the port of connection, malicious traffic never ingresses the network to cause any disruption to network connectivity.

4-8 Design Planning