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
Dec 17 19:43:09.508458 osdx cfgd[1460]: [341299]Completed change to active configuration
Dec 17 19:43:09.509287 osdx dhcpd[343135]: Wrote 0 leases to leases file.
Dec 17 19:43:09.520665 osdx OSDxCLI[341299]: User 'admin' committed the configuration.
Dec 17 19:43:09.549709 osdx OSDxCLI[341299]: User 'admin' left the configuration menu.
Dec 17 19:43:09.550664 osdx dhcpd[343135]: Server starting service.
Dec 17 19:43:09.698420 osdx OSDxCLI[341299]: User 'admin' executed a new command: 'system journal show | tail'.
Dec 17 19:43:10.408273 osdx dhcpd[343135]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Dec 17 19:43:11.408640 osdx dhcpd[343135]: DHCPOFFER on 10.0.0.5 to 10:00:00:00:00:02 via eth0
Dec 17 19:43:11.468240 osdx dhcpd[343135]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Dec 17 19:43:11.468274 osdx dhcpd[343135]: 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
Dec 17 19:43:12.579713 osdx systemd-journald[123332]: Runtime Journal (/run/log/journal/a189e667ab9f46898dbfc92a68a94f73) is 1.8M, max 13.8M, 11.9M free.
Dec 17 19:43:12.582536 osdx systemd-journald[123332]: Received client request to rotate journal, rotating.
Dec 17 19:43:12.582618 osdx systemd-journald[123332]: Vacuuming done, freed 0B of archived journals from /run/log/journal/a189e667ab9f46898dbfc92a68a94f73.
Dec 17 19:43:12.593685 osdx OSDxCLI[341299]: 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
Dec 17 19:43:12.579713 osdx systemd-journald[123332]: Runtime Journal (/run/log/journal/a189e667ab9f46898dbfc92a68a94f73) is 1.8M, max 13.8M, 11.9M free.
Dec 17 19:43:12.582536 osdx systemd-journald[123332]: Received client request to rotate journal, rotating.
Dec 17 19:43:12.582618 osdx systemd-journald[123332]: Vacuuming done, freed 0B of archived journals from /run/log/journal/a189e667ab9f46898dbfc92a68a94f73.
Dec 17 19:43:12.593685 osdx OSDxCLI[341299]: User 'admin' executed a new command: 'system journal clear'.
Dec 17 19:43:12.670621 osdx OSDxCLI[341299]: User 'admin' executed a new command: 'system journal show | tail'.
Dec 17 19:43:12.754815 osdx OSDxCLI[341299]: User 'admin' executed a new command: 'system journal show | tail'.
Dec 17 19:43:13.632292 osdx dhcpd[343191]: 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)
Dec 17 19:43:14.688289 osdx dhcpd[343191]: 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  2025/12/17 19:43:17  2025/12/18 07:43:17  2025/12/17 19:43:17

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
Dec 17 19:43:24.785834 osdx cfgd[1460]: [341299]Completed change to active configuration
Dec 17 19:43:24.787128 osdx dhcpd[343547]: Wrote 0 leases to leases file.
Dec 17 19:43:24.799390 osdx OSDxCLI[341299]: User 'admin' committed the configuration.
Dec 17 19:43:24.814824 osdx OSDxCLI[341299]: User 'admin' left the configuration menu.
Dec 17 19:43:24.820048 osdx dhcpd[343547]: Server starting service.
Dec 17 19:43:24.954664 osdx OSDxCLI[341299]: User 'admin' executed a new command: 'system journal show | tail'.
Dec 17 19:43:25.324999 osdx dhcpd[343547]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Dec 17 19:43:26.325967 osdx dhcpd[343547]: DHCPOFFER on 10.0.0.5 to 10:00:00:00:00:02 via eth0
Dec 17 19:43:26.372907 osdx dhcpd[343547]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Dec 17 19:43:26.372938 osdx dhcpd[343547]: 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
Dec 17 19:43:27.691930 osdx systemd-journald[123332]: Runtime Journal (/run/log/journal/a189e667ab9f46898dbfc92a68a94f73) is 1.8M, max 13.8M, 11.9M free.
Dec 17 19:43:27.695856 osdx systemd-journald[123332]: Received client request to rotate journal, rotating.
Dec 17 19:43:27.695942 osdx systemd-journald[123332]: Vacuuming done, freed 0B of archived journals from /run/log/journal/a189e667ab9f46898dbfc92a68a94f73.
Dec 17 19:43:27.702952 osdx OSDxCLI[341299]: 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
Dec 17 19:43:27.691930 osdx systemd-journald[123332]: Runtime Journal (/run/log/journal/a189e667ab9f46898dbfc92a68a94f73) is 1.8M, max 13.8M, 11.9M free.
Dec 17 19:43:27.695856 osdx systemd-journald[123332]: Received client request to rotate journal, rotating.
Dec 17 19:43:27.695942 osdx systemd-journald[123332]: Vacuuming done, freed 0B of archived journals from /run/log/journal/a189e667ab9f46898dbfc92a68a94f73.
Dec 17 19:43:27.702952 osdx OSDxCLI[341299]: User 'admin' executed a new command: 'system journal clear'.
Dec 17 19:43:27.778131 osdx OSDxCLI[341299]: User 'admin' executed a new command: 'system journal show | tail'.
Dec 17 19:43:27.851929 osdx OSDxCLI[341299]: User 'admin' executed a new command: 'system journal show | tail'.
Dec 17 19:43:28.521069 osdx dhcpd[343603]: 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)
Dec 17 19:43:29.592780 osdx dhcpd[343603]: 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  2025/12/17 19:43:32  2025/12/18 07:43:32  2025/12/17 19:43:32