NAC Appliance design question

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Aug 16th, 2008
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I have a customer with a central site and two branch office. Routing is configured on the WAN to connect all three locations. All servers and internet access are on the central site.


Customer wants to install NAC appliance. Do I need a NAC apliance at each location? Or do I just install it at the central location and use that NAC appliance for access control to the two remote sites as well.


Also how does NAC appliance apply access control to users coming into the network via Citrix or Cisco VPN Clients?


Thanks



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NAC Appliance (CAM & CAS = Clean Access Manager/Server) can be used in a Layer 3 Out Of Band design. This will provide you with centralized control.


It works by placing all unauthenticated switch ports into a unathentication VLAN. When a switch port goes up/up, the NAC CAS follows a set of rules you have established on the CAM to make decisions about the computer and user. It then will place that switch port into a VLAN 'dynamically' as dictated by the rules. Your switches must support these features (IOS level) and only Cisco products work with the CAM/CAS (well some others might, but it's a short list). When the port goes down/down the CAS senses this and returns the port to the unauthenticated VLAN.


For instance, if a user is a vendor, only requiring Internet access, you will have a VLAN for this purpose on all your switches and routed/trunked to your Internet Point of Presence. The CAS will see the switch port he/she jacks into come up/up. It will query the user and the computer and based upon the rules in the CAM, dynamically assign the wire port to the VLAN from the go-no-where unauthenticated VLAN.


If it were a company user, you could set it to check Anti-virus, levels of service packs, etc. before they were allowed on the network. It could also be set up to allow the person access to only the 'Finance' VLAN (for example) based upon their role in the company. It can do this remotely.


If you were to remediate VPN users, you could not do this in a dynamic, Out of Band fashion. You would need a second CAS (but not CAM) to operate In Band. This would then allow users in one Interface, traverse the CAS on out another interface on the appropriate VLAN. This is because it's impossible to apply multiple rules to a single port shared by multiple users. You would need a means to make decision on what VLAN the users accesses at the concentrator and move them off dynamically at the virtual interface. It's not supported.


Remember, NAC is performed at the switch port level. Citrix users would be regarded as local users. You could perform certain rule checking to allow them only onto your Citrix VLAN.


There is a Cisco Chalk Talk series on the NAC, use the URL below. It will teach you as much as you can absorb on the NAC appliances, how to use them and recommend their purchase to your clients.


http://www.cisco.com/en/US/prod/collateral/vpndevc/ps5707/ps8418/ps6128/prod_presentation0900aecd80549168.html

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