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DHCP restrictions with User Class

Posted on 2009-04-02
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Last Modified: 2012-06-27
We do have similar question to restrict non-Domain Computers to lease IP address.

Although if we add a new User class we can restrict a machine not to have available options.
i.e. Router address, DNS and WINS etc. but still the machine can have the IP address. good thing is that machine cannot cross the router, hence narrowing down the vunlnerability impact.

what if the requirment is to restrict the IP address Lease for the Machine which is not authorized either by means of Domain, User or Vendor Class or any ohter way.

Focus is to restrict any un authorized Machine to connects to production Network.
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Question by:Ovais60
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by:KCTS
ID: 24047934
Since the IP is issued before authentication can take place, then unless you impliment a 802.1x pre-authentication solution you have done just about everything you can do (its been made much simpler in Windows 2008).
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bluntTony earned 500 total points
ID: 24048482
Agree with KCTS - DHCP is a low level protocol which occurs without authentication.
You can, however, install a DLL which allows you to apply a MAC address filter in a text file. Set up a list of 'allowed' and/or 'denied' MAC addresses (which could be a pain depending on the size of your network)
See here: http://blogs.technet.com/teamdhcp/archive/2007/10/03/dhcp-server-callout-dll-for-mac-address-based-filtering.aspx
I have to say that while I am aware of this, I have never used it myself.
Maybe it is of interest to you....
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Author Comment

by:Ovais60
ID: 24057181
Thanks for your comments and assistance.

MAC address base filter option i have already in queue, but we are stuck to gather MAC addresses for 5000 + clients.

have you check the Symantec Network Access Control -> DHCP enforcer.

Seems its also use the User Class for the isolation.
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by:bluntTony
ID: 24067975
The Symantec DHCP enforcer runs on the DHCP server and requires that all hosts have the enforcer client service running on them before handing out valid IP addresses.
A host performing a DHCP discovery is given a 'quarantine' configuration so that the DHCP enforcer can authenticate it. Like you say, it uses a User class to provide the quarantine configuration. If the client is authenticated it is then given the correct IP config - if it fails, it remains with the quarantine config.
For this you would have to deploy the client out to all machines on your network. Have a look at this for a bit of reference  : ftp://ftp.symantec.com/public/japanese/products/symantec_network_access_control/51/manuals/SSEP_5_1_Integrated_Enforcer_for_Microsoft_DHCP_Servers.pdf
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Author Closing Comment

by:Ovais60
ID: 31565702
to Authenticate & Authorise DHCP requests is to use DHCP server Call out DLL. it can help you out to keep your network free from un-authorise requests! Thanks.
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