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
Mar 23 08:52:43.335682 osdx cfgd[1828]: [14779]Completed change to active configuration
Mar 23 08:52:43.348063 osdx OSDxCLI[14779]: User 'admin' committed the configuration.
Mar 23 08:52:43.365892 osdx OSDxCLI[14779]: User 'admin' left the configuration menu.
Mar 23 08:52:43.393842 osdx dhcpd[36305]: Wrote 0 leases to leases file.
Mar 23 08:52:43.453612 osdx dhcpd[36305]: Server starting service.
Mar 23 08:52:43.508416 osdx OSDxCLI[14779]: User 'admin' executed a new command: 'system journal show | tail'.
Mar 23 08:52:44.271104 osdx dhcpd[36305]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Mar 23 08:52:45.271495 osdx dhcpd[36305]: DHCPOFFER on 10.0.0.5 to 10:00:00:00:00:02 via eth0
Mar 23 08:52:45.330989 osdx dhcpd[36305]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Mar 23 08:52:45.331013 osdx dhcpd[36305]: DHCPOFFER on 10.0.0.5 to 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
Mar 23 08:52:46.270966 osdx systemd-journald[2086]: Runtime Journal (/run/log/journal/6b3b4e4818aa404284bc644df40f6904) is 1.8M, max 13.8M, 11.9M free.
Mar 23 08:52:46.273399 osdx systemd-journald[2086]: Received client request to rotate journal, rotating.
Mar 23 08:52:46.273481 osdx systemd-journald[2086]: Vacuuming done, freed 0B of archived journals from /run/log/journal/6b3b4e4818aa404284bc644df40f6904.
Mar 23 08:52:46.283746 osdx OSDxCLI[14779]: 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
Mar 23 08:52:46.270966 osdx systemd-journald[2086]: Runtime Journal (/run/log/journal/6b3b4e4818aa404284bc644df40f6904) is 1.8M, max 13.8M, 11.9M free.
Mar 23 08:52:46.273399 osdx systemd-journald[2086]: Received client request to rotate journal, rotating.
Mar 23 08:52:46.273481 osdx systemd-journald[2086]: Vacuuming done, freed 0B of archived journals from /run/log/journal/6b3b4e4818aa404284bc644df40f6904.
Mar 23 08:52:46.283746 osdx OSDxCLI[14779]: User 'admin' executed a new command: 'system journal clear'.
Mar 23 08:52:46.349055 osdx OSDxCLI[14779]: User 'admin' executed a new command: 'system journal show | tail'.
Mar 23 08:52:46.383122 osdx dhcpd[36362]: 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  2026/03/23 08:52:48  2026/03/23 20:52:48  2026/03/23 08:52:48

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
Mar 23 08:52:55.634507 osdx cfgd[1828]: [14779]Completed change to active configuration
Mar 23 08:52:55.635487 osdx dhcpd[36735]: Wrote 0 leases to leases file.
Mar 23 08:52:55.645983 osdx OSDxCLI[14779]: User 'admin' committed the configuration.
Mar 23 08:52:55.669883 osdx OSDxCLI[14779]: User 'admin' left the configuration menu.
Mar 23 08:52:55.676834 osdx dhcpd[36735]: Server starting service.
Mar 23 08:52:55.810494 osdx OSDxCLI[14779]: User 'admin' executed a new command: 'system journal show | tail'.
Mar 23 08:52:56.237860 osdx dhcpd[36735]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Mar 23 08:52:57.238783 osdx dhcpd[36735]: DHCPOFFER on 10.0.0.5 to 10:00:00:00:00:02 via eth0
Mar 23 08:52:57.297949 osdx dhcpd[36735]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Mar 23 08:52:57.297978 osdx dhcpd[36735]: DHCPOFFER on 10.0.0.5 to 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
Mar 23 08:52:58.504915 osdx systemd-journald[2086]: Runtime Journal (/run/log/journal/6b3b4e4818aa404284bc644df40f6904) is 1.8M, max 13.8M, 11.9M free.
Mar 23 08:52:58.508663 osdx systemd-journald[2086]: Received client request to rotate journal, rotating.
Mar 23 08:52:58.508725 osdx systemd-journald[2086]: Vacuuming done, freed 0B of archived journals from /run/log/journal/6b3b4e4818aa404284bc644df40f6904.
Mar 23 08:52:58.515783 osdx OSDxCLI[14779]: 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
Mar 23 08:52:58.504915 osdx systemd-journald[2086]: Runtime Journal (/run/log/journal/6b3b4e4818aa404284bc644df40f6904) is 1.8M, max 13.8M, 11.9M free.
Mar 23 08:52:58.508663 osdx systemd-journald[2086]: Received client request to rotate journal, rotating.
Mar 23 08:52:58.508725 osdx systemd-journald[2086]: Vacuuming done, freed 0B of archived journals from /run/log/journal/6b3b4e4818aa404284bc644df40f6904.
Mar 23 08:52:58.515783 osdx OSDxCLI[14779]: User 'admin' executed a new command: 'system journal clear'.
Mar 23 08:52:58.625713 osdx OSDxCLI[14779]: User 'admin' executed a new command: 'system journal show | tail'.
Mar 23 08:52:58.752008 osdx OSDxCLI[14779]: User 'admin' executed a new command: 'system journal show | tail'.
Mar 23 08:52:59.402147 osdx dhcpd[36792]: 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)
Mar 23 08:53:00.453691 osdx dhcpd[36792]: 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 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  2026/03/23 08:53:03  2026/03/23 20:53:03  2026/03/23 08:53:03