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multiple mac-addresses on mac-auth port not seen on client

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  • 1.  multiple mac-addresses on mac-auth port not seen on client

    Posted May 03, 2023 08:59 AM

    Hello

    Does anyone have seen this behaviour and found the source of it? Not sure if it is switch or clearpass related, but it uses up Access Licenses and pushes the total license count of our customer above the maximum licenses they bought...

    They have a ClearPass setup with Aruba A-OS and OS-CX switches and see following behaviour on both switches:

    When a Windows 10/11 domain client with USB-C docking station is connected, sometimes the switchport sees multiple (random?) mac-addresses and triggers authentication. The client is directly connected to the switch and authenticates correct with dot1x. Whe don't see the mac-addresses that the switch sees on the windows clients.

    With "sometimes", I meen this behaviour is not always present for all clients and sometimes gone after a client reboot (port shut/no shut).

    I have tried replicating this and was first thinking the USB-C Dockings are the root cause, but the issues is seen onmultiple vendors/types of dockings.

    This is an example of the mac-addresses seen alongside the dot1x authentication:

    # show port-access clients 16

     Port Access Client Status

      Port  Client Name   MAC Address   IP Address      User Role         Type  VLAN
      ----- ------------- ------------- --------------- ----------------- ----- -------------------------------------------------------
      16                  000000-17df02 n/a                               8021X
      16                  000000-180de9 n/a                               8021X
      16                  000000-1828e5 n/a                               8021X
      16                  203230-30204f n/a                               8021X
      16                  400001-000000 n/a                               8021X
      16                  4297ef-7ed70f n/a                               8021X
      16    Kristel.Ae... 84a93e-235389 n/a                               8021X 3
      16                  9c004c-002f0c n/a                               8021X
      16    00000017df02  000000-17df02 n/a                               MAC
      16    000000180de9  000000-180de9 n/a                               MAC
      16    0000001828e5  000000-1828e5 n/a                               MAC
      16    02313007696e  023130-07696e n/a                               MAC   22
      16    0a030a2f0088  0a030a-2f0088 n/a                               MAC   22
      16    400001000000  400001-000000 n/a                               MAC
      16    4297ef7ed70f  4297ef-7ed70f n/a                               MAC
      16    447754754562  447754-754562 n/a                               MAC   22
      16    9c004c002f0c  9c004c-002f0c n/a                               MAC
      16    d66b73c6ae57  d66b73-c6ae57 n/a                               MAC   22
      16    fc0303c62575  fc0303-c62575 n/a                               MAC   22


    This is the port config on the A-OS switch:

    interface 16
       name "1.9.08 - BH -"
       tagged vlan 40
       untagged vlan 254
       lldp enable-notification
       aaa port-access authenticator
       aaa port-access authenticator max-requests 1
       aaa port-access authenticator client-limit 2
       aaa port-access mac-based
       aaa port-access mac-based addr-limit 5
       aaa port-access mac-based logoff-period 28800
       aaa port-access mac-based unauth-vid 22
       spanning-tree bpdu-protection
       exit

    and this is the config on the OS-CX switch:

    interface 2/1/18
        description LAN_Clients
        no shutdown
        no routing
        vlan access 254
        rate-limit broadcast 300 pps
        spanning-tree bpdu-guard
        aaa authentication port-access client-limit 2
        aaa authentication port-access critical-role GUEST-VLAN
        aaa authentication port-access dot1x authenticator
            max-eapol-requests 3
            max-retries 1
            enable
        aaa authentication port-access mac-auth
            reauth-period 28800
            enable
        loop-protect
        exit

    Kind regards

    Wouter



  • 2.  RE: multiple mac-addresses on mac-auth port not seen on client

    Posted May 03, 2023 11:49 AM

    No unmanaged layer2 switch here right?  Any VMs on this endpoint?  I have also seen some video conference applications doing this.  Updated drivers on the USB dongle?




  • 3.  RE: multiple mac-addresses on mac-auth port not seen on client

    Posted May 04, 2023 10:26 AM

    no unmanaged switch for sure and no vms on the endpoints.

    Did not check USB docking drivers yet, but sinse multimple make/models are infected, I doubt this will be the issue. Although, we will check this to be sure.

    The conference applications will be checked, thanks for the tip!




  • 4.  RE: multiple mac-addresses on mac-auth port not seen on client

    Posted May 04, 2023 01:35 PM

    Hi Wouter,

    as it looks, incoming and outgoing packets are authenticated on the A-OS switch. By default direction-mode both is enabled.

    You need to change this, use the command "aaa port-access 16 controlled-direction in".  This will only authenticate packets that the client sends into the switch.

    Check the config with "sh port-access config".
    In my example, ports 1,2,3 and 8 are set to direction "in". Ports 4-7 and 9-10 are set to direction "both".

    SW01# sh port-access config

     Port Access Status Summary

      Port-access authenticator activated [No] : Yes
      Allow RADIUS-assigned dynamic (GVRP) VLANs [No] : No
      Use LLDP data to authenticate [No] : No
      Dot1X EAP Identifier Compliance [Disabled] : Disabled
      Allow incremental EAP identifier only [Disabled] : Disabled

            802.1X  802.1X   Web      Mac      LMA   Cntrl Mixed    Speed
      Port  Supp    Auth     Auth     Auth     Auth  Dir   Mode     VSA   MBV
      ----- ------- -------- -------- -------- ----- ----- -------- ----- ---
      1     No      No       No       No       No    in    No       No    Yes
      2     No      Yes      No       Yes      No    in    No       No    Yes
      3     No      No       No       No       No    in    No       No    Yes
      4     No      No       No       No       No    both  No       No    Yes
      5     No      No       No       No       No    both  No       No    Yes
      6     No      No       No       No       No    both  No       No    Yes
      7     No      No       No       No       No    both  No       No    Yes
      8     No      No       No       No       No    in    No       No    Yes
      9     No      No       No       No       No    both  No       No    Yes
      10    No      No       No       No       No    both  No       No    Yes



    ------------------------------
    Regards,

    Waldemar
    ACCX # 1377, ACEP, ACA - Network Security
    If you find my answer useful, consider giving kudos and/or mark as solution
    ------------------------------



  • 5.  RE: multiple mac-addresses on mac-auth port not seen on client

    Posted May 09, 2023 05:58 AM

    Hi Lord

    I don't think you understand the functionality of the command "aaa port-access <int> controlled-direction in", this only allows egress traffic to the client without the client being authenticated.

    The authentication of the MAC-address is done because the switch sees this mac-addresses as connected to this port. unless this would be a bug, but since we see this on both A-OS and OS-CX switches, I don't think that is the case.




  • 6.  RE: multiple mac-addresses on mac-auth port not seen on client

    Posted May 10, 2023 07:41 AM

    Hi Wouter,
    you are right, I did not use the command for a while. 
    I looked in the guide and tried it in the lab, the command behaves as you describe.

    The question is what is causing the problem. If there is a bug, the problem would occur on aos switches or cx switches, but not on both models at the same time.

    Do you see the mac addresses on the switch on other ports as well? Or on the windows pc in the arp cache or with wireshark?



    ------------------------------
    Regards,

    Waldemar
    ACCX # 1377, ACEP, ACA - Network Security
    If you find my answer useful, consider giving kudos and/or mark as solution
    ------------------------------