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Prevent IP Address Assignment via MAC Addr


I found this 12 year old thread,

 Block certain mac address to get ip from dhcp pool 

and would like to know if it is now possible to prevent the assignment of IP addresses to specific MAC addresses.


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  • Toggling Clients with static mappings only in the UTM dhcp server setting

    Great suggestion, thank you! I will give this a try.

    more detail with respect to why you're trying to block these clients?

    The hosts are unknown. I'm hoping that blocking them will cause them to cease functioning, revealing which hosts they are, AND to prevent the unnecessary use of my 50 IP address allocation.

  • tThe static mappings option will work then.  In testing, if no other dhcp server (you can have *multiple dhcp servers for the same interface so long as their ip assignments don't overlap) exists for the given interface then the device is not assigned any ip at all and defaults to a which goes nowhere.

    I'm using this arrangement to assign specific ip's to known devices, and other ip's within the same subnet to unknown devices.

    For known devices:

    For unknown devices:

    Why?  Unknown devices get different web filtering settings applied than known devices.

    Note! The above will not work for ipv6 if using slaac/stateless assignment. Some mechanism of setting vlan will need to be used to block them so the device requests never reach UTM in the first place.

    I'm looking forward to reading how  implements the mac quarantine scheme.

  • Great suggestion, thank you! I will give this a try.

    Woo-hoo, it worked!