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How To Redirect Traffic to NAC Using Proxy DNS

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TitleHow To Redirect Traffic to NAC Using Proxy DNS
This article shows how to configure the NAC  to redirect users for authentication using ProxyDNS
This is the least secure of the  three methods to force user traffic to the NAC because the configuration is done on the  client and out of the control of the network administrator.
  • NAC
  • Captive Portal
1.  Enable the End-System Distributed Cache on both NetSight server and NAC

NAC Manager,
1.  Click Tools> Options> NAC Manager>
2.  Click Advanced Settings
3.  Check “Enable distributed end-system cache”.
4.  Restart the server.

NAC appliance,

1.  Click NAC appliance on the tree
2. Click view in NAC Manager 
3.  Click the Configuration tab in the right pane  . 
4.  Click on Advanced Configuration button
 5.  Check “Enable distributed end-system cache”.
6.  Enforce the NAC appliance

II.  Configure the DHCP server to return 2 DNS server IP’s to clients  
Primary DNS=real DNS Server IP address,
secondary DNS=NAC Gateway’s IP address.

III. enable DNS Proxy on appliance by editing the “/opt/nac/server/config/” file and un-commenting the “DNS_PROXY_ENABLE=true” line.


4.  Restart dnsProxy process on NAC appliance (

/opt/nac/server/ restart)

5. Configure the unregistered policy or ACL to “deny” DNS access to the Primary (real) DNS

server. This is so the client will try the Secondary IP, which is the NAC gateway.

Additional notes
the Allowed URL feature may not work properly in DNS Proxy setup. To fix this problem, enable DNS on the NAC appliance during the NAC appliance install. To enable the DNS during the install, answer these questions:

Type the IP address of the name server 1.  Type the domain name for NAC-Appliance-1 []:

When enabling/disabling MAC Reg and enforce on NAC Manager, it will take a couple of minutes to sync this change to the dnsProxy process. The messages in /var/log/dnsProxy.log will indicate when the synching occurs.




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