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 05 00:04:57.292535 osdx cfgd[1648]: [372728]Completed change to active configuration
May 05 00:04:57.293698 osdx dhcpd[377123]: Wrote 0 leases to leases file.
May 05 00:04:57.304474 osdx OSDxCLI[372728]: User 'admin' committed the configuration.
May 05 00:04:57.341231 osdx OSDxCLI[372728]: User 'admin' left the configuration menu.
May 05 00:04:57.354732 osdx dhcpd[377123]: Server starting service.
May 05 00:04:57.457873 osdx OSDxCLI[372728]: User 'admin' executed a new command: 'system journal show | tail'.
May 05 00:04:58.348286 osdx dhcpd[377123]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
May 05 00:04:59.349033 osdx dhcpd[377123]: DHCPOFFER on 10.0.0.5 to 10:00:00:00:00:02 via eth0
May 05 00:04:59.392287 osdx dhcpd[377123]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
May 05 00:04:59.392315 osdx dhcpd[377123]: 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
May 05 00:05:00.160652 osdx systemd-journald[1908]: Runtime Journal (/run/log/journal/9e2a66651dea45ed982d8152051049c2) is 1.9M, max 13.8M, 11.8M free.
May 05 00:05:00.162574 osdx systemd-journald[1908]: Received client request to rotate journal, rotating.
May 05 00:05:00.162617 osdx systemd-journald[1908]: Vacuuming done, freed 0B of archived journals from /run/log/journal/9e2a66651dea45ed982d8152051049c2.
May 05 00:05:00.170471 osdx OSDxCLI[372728]: 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 05 00:05:00.160652 osdx systemd-journald[1908]: Runtime Journal (/run/log/journal/9e2a66651dea45ed982d8152051049c2) is 1.9M, max 13.8M, 11.8M free.
May 05 00:05:00.162574 osdx systemd-journald[1908]: Received client request to rotate journal, rotating.
May 05 00:05:00.162617 osdx systemd-journald[1908]: Vacuuming done, freed 0B of archived journals from /run/log/journal/9e2a66651dea45ed982d8152051049c2.
May 05 00:05:00.170471 osdx OSDxCLI[372728]: User 'admin' executed a new command: 'system journal clear'.
May 05 00:05:00.242868 osdx OSDxCLI[372728]: User 'admin' executed a new command: 'system journal show | tail'.
May 05 00:05:00.322192 osdx OSDxCLI[372728]: User 'admin' executed a new command: 'system journal show | tail'.
May 05 00:05:00.444253 osdx dhcpd[377180]: 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 05 00:05:01.484156 osdx dhcpd[377180]: 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  2026/05/05 00:05:04  2026/05/05 12:05:04  2026/05/05 00:05:04

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 05 00:05:11.457215 osdx cfgd[1648]: [372728]Completed change to active configuration
May 05 00:05:11.459765 osdx dhcpd[377564]: Wrote 0 leases to leases file.
May 05 00:05:11.471465 osdx OSDxCLI[372728]: User 'admin' committed the configuration.
May 05 00:05:11.486219 osdx OSDxCLI[372728]: User 'admin' left the configuration menu.
May 05 00:05:11.492187 osdx dhcpd[377564]: Server starting service.
May 05 00:05:11.625650 osdx OSDxCLI[372728]: User 'admin' executed a new command: 'system journal show | tail'.
May 05 00:05:12.245575 osdx dhcpd[377564]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
May 05 00:05:13.246547 osdx dhcpd[377564]: DHCPOFFER on 10.0.0.5 to 10:00:00:00:00:02 via eth0
May 05 00:05:13.321561 osdx dhcpd[377564]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
May 05 00:05:13.321605 osdx dhcpd[377564]: 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
May 05 00:05:14.285909 osdx systemd-journald[1908]: Runtime Journal (/run/log/journal/9e2a66651dea45ed982d8152051049c2) is 1.8M, max 13.8M, 11.9M free.
May 05 00:05:14.288086 osdx systemd-journald[1908]: Received client request to rotate journal, rotating.
May 05 00:05:14.288139 osdx systemd-journald[1908]: Vacuuming done, freed 0B of archived journals from /run/log/journal/9e2a66651dea45ed982d8152051049c2.
May 05 00:05:14.296131 osdx OSDxCLI[372728]: 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 05 00:05:14.285909 osdx systemd-journald[1908]: Runtime Journal (/run/log/journal/9e2a66651dea45ed982d8152051049c2) is 1.8M, max 13.8M, 11.9M free.
May 05 00:05:14.288086 osdx systemd-journald[1908]: Received client request to rotate journal, rotating.
May 05 00:05:14.288139 osdx systemd-journald[1908]: Vacuuming done, freed 0B of archived journals from /run/log/journal/9e2a66651dea45ed982d8152051049c2.
May 05 00:05:14.296131 osdx OSDxCLI[372728]: User 'admin' executed a new command: 'system journal clear'.
May 05 00:05:14.356957 osdx OSDxCLI[372728]: User 'admin' executed a new command: 'system journal show | tail'.
May 05 00:05:14.369189 osdx dhcpd[377621]: 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  2026/05/05 00:05:16  2026/05/05 12:05:16  2026/05/05 00:05:16