Check-Mac-Address

These scenarios show how the check-mac-address feature works for the DHCP server

../../../_images/check-mac-address.svg

Test Check MAC Address

Description

The check-mac-address option filters packets if there are differences between the MAC address found at the ethernet header and the MAC address found in the DHCP packet. To check this option, you should send packets with these differences and enable this option to see if warnings appear in your logs. Also, this test checks how the server behaves under normal conditions.

Scenario

Step 1: Set the following configuration in DUT0:

set interfaces ethernet eth0 address 10.0.0.1/24
set service dhcp-server shared-network dhcp subnet 10.0.0.0/24 start 10.0.0.5 stop 10.0.0.5
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'

Step 2: Run command system journal show | tail at DUT0 and check if output contains the following tokens:

DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Show output
May 11 23:21:50.186606 osdx OSDxCLI[232834]: User 'admin' added a new cfg line: 'show working'.
May 11 23:21:50.371674 osdx kernel: 8021q: adding VLAN 0 to HW filter on device eth0
May 11 23:21:50.624330 osdx systemd[1]: Started dhcpd@main.service - "DHCP Server Service instance main".
May 11 23:21:50.627102 osdx cfgd[1244]: [232834]Completed change to active configuration
May 11 23:21:50.628718 osdx dhcpd[237870]: Wrote 0 leases to leases file.
May 11 23:21:50.668105 osdx OSDxCLI[232834]: User 'admin' committed the configuration.
May 11 23:21:50.695820 osdx dhcpd[237870]: Server starting service.
May 11 23:21:50.713044 osdx OSDxCLI[232834]: User 'admin' left the configuration menu.
May 11 23:21:50.893750 osdx OSDxCLI[232834]: User 'admin' executed a new command: 'system journal show | tail'.
May 11 23:21:51.539351 osdx dhcpd[237870]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0

Step 3: Modify the following configuration lines in DUT0:

set service dhcp-server check-mac-address

Step 4: Run command system journal clear at DUT0.

Step 5: Run command system journal show | tail at DUT0 and check if output does not contain the following tokens:

DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Show output
May 11 23:21:52.992864 osdx systemd-journald[118835]: Runtime Journal (/run/log/journal/f55f446d40464b198e70fbabb9c21674) is 2.2M, max 15.3M, 13.0M free.
May 11 23:21:52.995781 osdx systemd-journald[118835]: Received client request to rotate journal, rotating.
May 11 23:21:52.995886 osdx systemd-journald[118835]: Vacuuming done, freed 0B of archived journals from /run/log/journal/f55f446d40464b198e70fbabb9c21674.
May 11 23:21:53.013000 osdx OSDxCLI[232834]: User 'admin' executed a new command: 'system journal clear'.

Step 6: Run command system journal show | tail at DUT0 and check if output contains the following tokens:

MAC received in DHCP packet (10:00:00:00:00:02) is different than source MAC in ethernet header (10:00:00:00:00:01)
Show output
May 11 23:21:52.992864 osdx systemd-journald[118835]: Runtime Journal (/run/log/journal/f55f446d40464b198e70fbabb9c21674) is 2.2M, max 15.3M, 13.0M free.
May 11 23:21:52.995781 osdx systemd-journald[118835]: Received client request to rotate journal, rotating.
May 11 23:21:52.995886 osdx systemd-journald[118835]: Vacuuming done, freed 0B of archived journals from /run/log/journal/f55f446d40464b198e70fbabb9c21674.
May 11 23:21:53.013000 osdx OSDxCLI[232834]: User 'admin' executed a new command: 'system journal clear'.
May 11 23:21:53.116696 osdx OSDxCLI[232834]: User 'admin' executed a new command: 'system journal show | tail'.
May 11 23:21:53.244785 osdx OSDxCLI[232834]: User 'admin' executed a new command: 'system journal show | tail'.
May 11 23:21:53.639344 osdx dhcpd[237915]: MAC received in DHCP packet (10:00:00:00:00:02) is different than source MAC in ethernet header (10:00:00:00:00:01)

Step 7: Set the following configuration in DUT1:

set interfaces ethernet eth0 mac '10:00:00:00:00:05'
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'

Step 8: Modify the following configuration lines in DUT1:

set interfaces ethernet eth0 address dhcp

Step 9: Run command interfaces ethernet eth0 show at DUT1 and check if output contains the following tokens:

10.0.0.5
Show output
-----------------------------------------------------------------
Name           IP Address           Admin  Oper  Vrf  Description
-----------------------------------------------------------------
eth0  10.0.0.5/24                   up     up
      fe80::dcad:beff:feef:6c10/64

Step 10: Run command service dhcp-server show leases main | grep 10.0.0.5 at DUT0 and check if output contains the following tokens:

10:00:00:00:00:05
Show output
10.0.0.5   10:00:00:00:00:05  2025/05/11 23:21:56  2025/05/12 11:21:56  2025/05/11 23:21:56

Test Check MAC Address VRF

Description

This scenario configures a DHCP server with VRF instead of regular interfaces and checks the check-mac-address option. To check this option, you will need to send packets with differences in the Source MAC for the link layer and the client MAC from the application layer.

Scenario

Step 1: Set the following configuration in DUT0:

set interfaces ethernet eth0 address 10.0.0.1/24
set interfaces ethernet eth0 vrf VRF0
set service dhcp-server shared-network dhcp local-vrf VRF0
set service dhcp-server shared-network dhcp subnet 10.0.0.0/24 start 10.0.0.5 stop 10.0.0.6
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'
set system vrf VRF0

Step 2: Run command system journal show | tail at DUT0 and check if output contains the following tokens:

DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Show output
May 11 23:22:06.638741 osdx (udev-worker)[238114]: Network interface NamePolicy= disabled on kernel command line.
May 11 23:22:06.661456 osdx kernel: 8021q: adding VLAN 0 to HW filter on device eth0
May 11 23:22:06.777464 osdx kernel: 8021q: adding VLAN 0 to HW filter on device eth0
May 11 23:22:06.906332 osdx systemd[1]: Started dhcpd@VRF0.service - "DHCP Server Service instance VRF0".
May 11 23:22:06.909120 osdx cfgd[1244]: [232834]Completed change to active configuration
May 11 23:22:06.910061 osdx dhcpd[238193]: Wrote 0 leases to leases file.
May 11 23:22:06.965354 osdx OSDxCLI[232834]: User 'admin' committed the configuration.
May 11 23:22:06.973704 osdx dhcpd[238193]: Server starting service.
May 11 23:22:07.009968 osdx OSDxCLI[232834]: User 'admin' left the configuration menu.
May 11 23:22:07.077407 osdx dhcpd[238193]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0

Step 3: Modify the following configuration lines in DUT0:

set service dhcp-server check-mac-address

Step 4: Run command system journal clear at DUT0.

Step 5: Run command system journal show | tail at DUT0 and check if output does not contain the following tokens:

DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Show output
May 11 23:22:08.071456 osdx systemd-journald[118835]: Runtime Journal (/run/log/journal/f55f446d40464b198e70fbabb9c21674) is 2.0M, max 15.3M, 13.3M free.
May 11 23:22:08.073464 osdx systemd-journald[118835]: Received client request to rotate journal, rotating.
May 11 23:22:08.073545 osdx systemd-journald[118835]: Vacuuming done, freed 0B of archived journals from /run/log/journal/f55f446d40464b198e70fbabb9c21674.
May 11 23:22:08.088424 osdx OSDxCLI[232834]: User 'admin' executed a new command: 'system journal clear'.
May 11 23:22:08.121149 osdx dhcpd[238235]: MAC received in DHCP packet (10:00:00:00:00:02) is different than source MAC in ethernet header (10:00:00:00:00:01)

Step 6: Run command system journal show | tail at DUT0 and check if output contains the following tokens:

MAC received in DHCP packet (10:00:00:00:00:02) is different than source MAC in ethernet header (10:00:00:00:00:01)
Show output
May 11 23:22:08.071456 osdx systemd-journald[118835]: Runtime Journal (/run/log/journal/f55f446d40464b198e70fbabb9c21674) is 2.0M, max 15.3M, 13.3M free.
May 11 23:22:08.073464 osdx systemd-journald[118835]: Received client request to rotate journal, rotating.
May 11 23:22:08.073545 osdx systemd-journald[118835]: Vacuuming done, freed 0B of archived journals from /run/log/journal/f55f446d40464b198e70fbabb9c21674.
May 11 23:22:08.088424 osdx OSDxCLI[232834]: User 'admin' executed a new command: 'system journal clear'.
May 11 23:22:08.121149 osdx dhcpd[238235]: MAC received in DHCP packet (10:00:00:00:00:02) is different than source MAC in ethernet header (10:00:00:00:00:01)
May 11 23:22:08.184333 osdx OSDxCLI[232834]: User 'admin' executed a new command: 'system journal show | tail'.

Step 7: Set the following configuration in DUT1:

set interfaces ethernet eth0 mac '10:00:00:00:00:05'
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'

Step 8: Modify the following configuration lines in DUT1:

set interfaces ethernet eth0 address dhcp

Step 9: Run command interfaces ethernet eth0 show at DUT1 and check if output contains the following tokens:

10.0.0.5
Show output
-----------------------------------------------------------------
Name           IP Address           Admin  Oper  Vrf  Description
-----------------------------------------------------------------
eth0  10.0.0.5/24                   up     up
      fe80::dcad:beff:feef:6c10/64

Step 10: Run command service dhcp-server show leases VRF0 | grep 10.0.0.5 at DUT0 and check if output contains the following tokens:

10:00:00:00:00:05
Show output
10.0.0.5   10:00:00:00:00:05  2025/05/11 23:22:10  2025/05/12 11:22:10  2025/05/11 23:22:10