DHCP Server Callout DLL for MAC Address based filtering – MAC Address List File Format

Looking at the problem in configuring Mac Address List File while configuring callout DLL for Mac Address based filtering, here are some detailed tips which will help you in verifying your configuration with one below…

·         File should contain action followed by MAC address list as show in below format. There is stringent check on the format and hence it needs to be strictly followed including braces etc.






      ·         First line in the file should specify the action. Action can be either ALLOW or DENY. Please note the braces around action.

o   When action is specified as ALLOW, all requests from MAC address present in this list will be served by dhcp servers. All requests originating from MAC address not present in this list will be ignored.

o   When action is specified as DENY, all request from MAC address present in the list will be ignored by dhcp servers. All requests from MAC addresses not present in this list will be severed by dhcp server.

o   Only one action out of ALLOW or DENY can be specified in MAC Address List File

·         MAC address should be specified in format XXXXXXXXXXXX (where X can be hex digit 0 – F).There should not any delimiter such as -,  : in MAC address.  Each MAC address should be specified in separate line.

·         If there is any error in MAC Address List File, it will be logged into CalloutErrorLogFile or default error log file.  Following is expected behavior of dll in cases of errors

o   If the action is not specified correctly, then dhcp server will function as if there is no callout dll i.e. none of the requests will be ignored. Error for the same will be logged in error log file.

o   If one or more MAC addresses are not specified correctly, then in this case those MAC address entries will be ignored. Error for the same will be logged in error log file.


Govind [MSFT]


Comments (23)

  1. teamdhcp says:

    Hi Will,

    DHCP server in Windows Server 2008 R2 has builtin support for MAC address based filtering.

    Wild cards are allowed as suffixes in the specified MAC address filter.

    See blogs.technet.com/…/how-to-configure-link-layer-based-filtering.aspx



    Team DHCP

  2. teamdhcp says:

    Hey Bruno,

    Currently there is no option in this callout dll to insert comments.


    Raunak Pandya

    DHCP Server Team

  3. teamdhcp says:

    Yes you do, MACList.txt is read at the time of service startup only.


    Arun, Dhcp Team

  4. teamdhcp says:

    Hey Jim,

    The tool works in two modes, ALLOW/DENY depending on the first line in the MACList.txt file. If its working in ALLOW mode, the MAC addresses in the MACList.txt file will be allowed and rest denied. Similarly if in DENY mode, MAC Addresses in MACList.txt will be denied and rest all will be allowed.

    Raunak Pandya

    DHCP Server Team

  5. Anonymous says:

    Has support for Server 2003 x64 been added yet?  If not, I will have to use another DHCP server as the functionality provided by the callout DLL is required for my application.  Thanks!

    Matthew Monacelli

  6. teamdhcp says:


    You can move the SetupDHCPMacFilter.rtf file anywhere. However You shouldn’t be moving the location of the MacFilterCallout.dll from the location which you have specified in the registry while configuring the callout dll.


    Raunak Pandya

    DHCP Server Team

  7. teamdhcp says:


      We will be releasing the x64 version, in a few weeks.     Stay tuned via the blog.



    Team DHCP

  8. teamdhcp says:


      You will require a different DLL (currently in testing) that supports 64 bit OSs.

      You can contact me at msnetworkteam_AT_live_DOT_com for an early version of this dll.


  9. teamdhcp says:

    Michael VanDusen,

      The DHCP Server does not specifically allow or deny based on the Operating system of the client.    Check that the MAC address of the client is in the filter file.


    Team DHCP

  10. Anonymous says:

    should i leave the MacFilterCallout.dll and SetupDHCPMacFilter.rtf in the default folder are should i move them to the folder i create on the root of my C drive

  11. Michael VanDusen says:

    I noticed that the machines that I am trying to get a ip from the DHCP server are Vista Buisness.  Is there anything going on with this not working on Vista Business

  12. Anonymous says:

    This addon is great, I would love to see wildcard support though – so I could stop the random students iPhone from hitting us 🙂

  13. teamdhcp says:


    If you are using the MAC Addree filtering Callout DLL you do need to restart DHCP Server service everytime you make any change in the MACList.txt file irrespective of the OS (WS03 or WS08).

    You are correct. You cannot have both Allow and Deny at the same time. However, DHCP Server in WS08R2 does support MAC Address filtering in an advanced way. For more information refer to the blogpost, blogs.technet.com/…/link-layer-based-filtering.aspx


    Raunak Pandya

  14. Bruno Leal says:

    I need insert comments on my file MAClist.txt where stay all of my mac address.

    I want to do this for identify all of my MACs.



    000a0c0d1254         ‘machine01

    000d0c4a6723         ‘machine02

    Is there any option to do this?

  15. Jim Malay says:

    Do you have to also enter DHCP addresses you wich to ALLOW or just the ones you want to DENY.

  16. Shadab1 says:

    this dll setting is neither working nor generating any error on my windows server 2003 64 bit platform while i have checked all the settings

  17. Jonathan Notice says:

    I just installed this tool, and I am really happy that this tool. Will post more when the user start using in the am.


  18. coco says:

    this tool works great with one exception.  We have it set to a allow list of MAC addresses.  The problem that we have comes with wireless access points (LinkSys Routers). The MAC for the laptops are in the allow list but the DHCP will not assign an ip address.  I have even inserted the MAC for the wireless access router but still no luck.  Any suggestions? (I know the wireless SSID and key are correct because when a static ip is assigned in the wireless connection config the computer connects to the network)

  19. Bob Hyatt says:

    Is there a version of this DLL for server2008?

  20. Will Turner says:

    This tool is excellent.  I love the ability to block MAC addresses as I see fit.  In the next revision I would love to see wildcard characters supported as well.  Any idea if this is in the works or even possible?  Thanks for your hard work!

  21. TW says:


    Do we need to restart server every time there's a change in the MAC Address list? Thanks

  22. TW says:


    If it's for Windows Server 2008, do we also need to restart server every time there's a change in the MAC Address list or this procedure only for Windows Server 2003?

    For the MAC Address list, means that we can't have both allow and deny list in the same MAClist file (or even create 2 MAClists file to split the action cause looks from the registry it only read one file) like this below, right?


    # MAC Addresses allowed to get IP




    # MAC Addresses denied to get IP




  23. RoelvanSchilt says:

    Hi All,

    I found an option to add a description with the MAC-Address, you need to work with the # sign,

    For Example:


    000a0c0d1254 # Machine01

    000a0c0d1234 # Machine02

    000a0c0d1355 # Machine03

    So adding a description ain't that hard 😉


    Roel van Schilt