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
Aug 20 10:29:55.696366 osdx cfgd[1656]: [200442]Completed change to active configuration
Aug 20 10:29:55.696676 osdx dhcpd[210760]: Wrote 0 leases to leases file.
Aug 20 10:29:55.711115 osdx OSDxCLI[200442]: User 'admin' committed the configuration.
Aug 20 10:29:55.729405 osdx OSDxCLI[200442]: User 'admin' left the configuration menu.
Aug 20 10:29:55.738126 osdx dhcpd[210760]: Server starting service.
Aug 20 10:29:55.874878 osdx OSDxCLI[200442]: User 'admin' executed a new command: 'system journal show | tail'.
Aug 20 10:29:56.416893 osdx dhcpd[210760]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Aug 20 10:29:57.417904 osdx dhcpd[210760]: DHCPOFFER on 10.0.0.5 to 10:00:00:00:00:02 via eth0
Aug 20 10:29:57.461061 osdx dhcpd[210760]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Aug 20 10:29:57.461098 osdx dhcpd[210760]: 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
Aug 20 10:29:58.633735 osdx systemd-journald[1956]: Runtime Journal (/run/log/journal/5531ee11c77d43acb462311bc7f53dec) is 2.0M, max 15.3M, 13.3M free.
Aug 20 10:29:58.634209 osdx systemd-journald[1956]: Received client request to rotate journal, rotating.
Aug 20 10:29:58.634239 osdx systemd-journald[1956]: Vacuuming done, freed 0B of archived journals from /run/log/journal/5531ee11c77d43acb462311bc7f53dec.
Aug 20 10:29:58.644161 osdx OSDxCLI[200442]: 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
Aug 20 10:29:58.633735 osdx systemd-journald[1956]: Runtime Journal (/run/log/journal/5531ee11c77d43acb462311bc7f53dec) is 2.0M, max 15.3M, 13.3M free.
Aug 20 10:29:58.634209 osdx systemd-journald[1956]: Received client request to rotate journal, rotating.
Aug 20 10:29:58.634239 osdx systemd-journald[1956]: Vacuuming done, freed 0B of archived journals from /run/log/journal/5531ee11c77d43acb462311bc7f53dec.
Aug 20 10:29:58.644161 osdx OSDxCLI[200442]: User 'admin' executed a new command: 'system journal clear'.
Aug 20 10:29:58.725052 osdx OSDxCLI[200442]: User 'admin' executed a new command: 'system journal show | tail'.
Aug 20 10:29:58.801066 osdx OSDxCLI[200442]: User 'admin' executed a new command: 'system journal show | tail'.
Aug 20 10:29:59.552805 osdx dhcpd[210816]: 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)
Aug 20 10:30:00.600751 osdx dhcpd[210816]: 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  2025/08/20 10:30:03  2025/08/20 22:30:03  2025/08/20 10:30:03

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
Aug 20 10:30:10.586528 osdx dhcpd[211163]: Wrote 0 leases to leases file.
Aug 20 10:30:10.586822 osdx cfgd[1656]: [200442]Completed change to active configuration
Aug 20 10:30:10.597942 osdx OSDxCLI[200442]: User 'admin' committed the configuration.
Aug 20 10:30:10.621107 osdx OSDxCLI[200442]: User 'admin' left the configuration menu.
Aug 20 10:30:10.631545 osdx dhcpd[211163]: Server starting service.
Aug 20 10:30:10.784804 osdx OSDxCLI[200442]: User 'admin' executed a new command: 'system journal show | tail'.
Aug 20 10:30:11.133864 osdx dhcpd[211163]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Aug 20 10:30:12.134340 osdx dhcpd[211163]: DHCPOFFER on 10.0.0.5 to 10:00:00:00:00:02 via eth0
Aug 20 10:30:12.181970 osdx dhcpd[211163]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Aug 20 10:30:12.181992 osdx dhcpd[211163]: 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
Aug 20 10:30:13.506784 osdx systemd-journald[1956]: Runtime Journal (/run/log/journal/5531ee11c77d43acb462311bc7f53dec) is 2.0M, max 15.3M, 13.3M free.
Aug 20 10:30:13.507426 osdx systemd-journald[1956]: Received client request to rotate journal, rotating.
Aug 20 10:30:13.507464 osdx systemd-journald[1956]: Vacuuming done, freed 0B of archived journals from /run/log/journal/5531ee11c77d43acb462311bc7f53dec.
Aug 20 10:30:13.516232 osdx OSDxCLI[200442]: 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
Aug 20 10:30:13.506784 osdx systemd-journald[1956]: Runtime Journal (/run/log/journal/5531ee11c77d43acb462311bc7f53dec) is 2.0M, max 15.3M, 13.3M free.
Aug 20 10:30:13.507426 osdx systemd-journald[1956]: Received client request to rotate journal, rotating.
Aug 20 10:30:13.507464 osdx systemd-journald[1956]: Vacuuming done, freed 0B of archived journals from /run/log/journal/5531ee11c77d43acb462311bc7f53dec.
Aug 20 10:30:13.516232 osdx OSDxCLI[200442]: User 'admin' executed a new command: 'system journal clear'.
Aug 20 10:30:13.580231 osdx OSDxCLI[200442]: User 'admin' executed a new command: 'system journal show | tail'.
Aug 20 10:30:13.690238 osdx OSDxCLI[200442]: User 'admin' executed a new command: 'system journal show | tail'.
Aug 20 10:30:14.281665 osdx dhcpd[211219]: 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)
Aug 20 10:30:15.321749 osdx dhcpd[211219]: 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  2025/08/20 10:30:18  2025/08/20 22:30:18  2025/08/20 10:30:18