Access Control Concepts

 

Network Access Control Technologies

 

 

N o t e

In “Endpoint Integrity” on page 1-36,you will learn about solutions that test

 

endpoints for compliance with security policies. A network that enforces

 

endpoint integrity might include additional VLANs:

 

Test VLANs—The VLANs in which endpoints are placed after they

 

connect to the network but before they are tested by the network access

 

controller. A test VLAN can the same as the quarantine VLAN (described

 

below) or its own VLAN. In either case, the VLAN should be rather

 

restrictive.

 

Quarantine VLANs—The VLANs for endpoints that fail to comply with

 

the network’s security policies. A quarantine VLAN typically allows access

 

only to resources necessary for bringing endpoints into compliance.

 

Infected VLANs—The VLANs for endpoints on which the NAC 800

 

detects viruses, trojans, or other malware. While you can place infected

 

and quarantined endpoints in the same VLAN, you may want to separate

 

them. Then infected endpoints do not spread malware to the not-yet-

 

infected, but insecure quarantined endpoints.

 

These VLANs would be assigned to endpoints dynamically as part of the

 

policies sent out the RADIUS server (which, if you are using the ProCurve

 

NAC 800 could be the network access controller itself). Note, however, that

 

some network access controllers use different methods to quarantine end-

 

points—methods that do not rely on VLAN assignments at all.

 

ACLs

 

 

A VLAN assignment ensures that a user receives an IP address in the correct

 

subnet. ACLs control communications between subnets so that users in a

 

particular VLAN receive access to the correct resources.

An ACL is a series of rules, or access control entries (ACEs) to which a network device compares every packet that arrives. Although ACLs can operate either at Layer 2 or Layer 3/4, this design guide focuses on Layer 3/4 ACLs. An ACE in such an ACL controls traffic according to a variety of fields in the IP header:

Protocol (TCP, UDP, Internet Group Management Protocol [IGMP], and so forth)

IP source address

Source port

IP destination address

Destination port (for example, UDP 67 to allow DHCP traffic or 80 to allow Web traffic)

1-35