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
Jan 27 11:49:02.459699 osdx cfgd[1624]: [171716]Completed change to active configuration
Jan 27 11:49:02.460582 osdx dhcpd[180049]: Wrote 0 leases to leases file.
Jan 27 11:49:02.471998 osdx OSDxCLI[171716]: User 'admin' committed the configuration.
Jan 27 11:49:02.486006 osdx dhcpd[180049]: Server starting service.
Jan 27 11:49:02.509118 osdx OSDxCLI[171716]: User 'admin' left the configuration menu.
Jan 27 11:49:02.686552 osdx OSDxCLI[171716]: User 'admin' executed a new command: 'system journal show | tail'.
Jan 27 11:49:02.943366 osdx dhcpd[180049]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Jan 27 11:49:03.943755 osdx dhcpd[180049]: DHCPOFFER on 10.0.0.5 to 10:00:00:00:00:02 via eth0
Jan 27 11:49:03.995202 osdx dhcpd[180049]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Jan 27 11:49:03.995235 osdx dhcpd[180049]: 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
Jan 27 11:49:05.411220 osdx systemd-journald[1949]: Runtime Journal (/run/log/journal/19d27b7fd9034c15b59c452d6ca2fcd4) is 1.8M, max 13.8M, 11.9M free.
Jan 27 11:49:05.413731 osdx systemd-journald[1949]: Received client request to rotate journal, rotating.
Jan 27 11:49:05.413782 osdx systemd-journald[1949]: Vacuuming done, freed 0B of archived journals from /run/log/journal/19d27b7fd9034c15b59c452d6ca2fcd4.
Jan 27 11:49:05.421035 osdx OSDxCLI[171716]: 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
Jan 27 11:49:05.411220 osdx systemd-journald[1949]: Runtime Journal (/run/log/journal/19d27b7fd9034c15b59c452d6ca2fcd4) is 1.8M, max 13.8M, 11.9M free.
Jan 27 11:49:05.413731 osdx systemd-journald[1949]: Received client request to rotate journal, rotating.
Jan 27 11:49:05.413782 osdx systemd-journald[1949]: Vacuuming done, freed 0B of archived journals from /run/log/journal/19d27b7fd9034c15b59c452d6ca2fcd4.
Jan 27 11:49:05.421035 osdx OSDxCLI[171716]: User 'admin' executed a new command: 'system journal clear'.
Jan 27 11:49:05.486976 osdx OSDxCLI[171716]: User 'admin' executed a new command: 'system journal show | tail'.
Jan 27 11:49:05.585017 osdx OSDxCLI[171716]: User 'admin' executed a new command: 'system journal show | tail'.
Jan 27 11:49:06.119821 osdx dhcpd[180105]: 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)
Jan 27 11:49:07.175013 osdx dhcpd[180105]: 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  2026/01/27 11:49:10  2026/01/27 23:49:10  2026/01/27 11:49:10

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
Jan 27 11:49:17.836256 osdx cfgd[1624]: [171716]Completed change to active configuration
Jan 27 11:49:17.836572 osdx dhcpd[180477]: Wrote 0 leases to leases file.
Jan 27 11:49:17.851228 osdx OSDxCLI[171716]: User 'admin' committed the configuration.
Jan 27 11:49:17.872543 osdx OSDxCLI[171716]: User 'admin' left the configuration menu.
Jan 27 11:49:17.894252 osdx dhcpd[180477]: Server starting service.
Jan 27 11:49:18.023226 osdx OSDxCLI[171716]: User 'admin' executed a new command: 'system journal show | tail'.
Jan 27 11:49:18.355062 osdx dhcpd[180477]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Jan 27 11:49:19.356135 osdx dhcpd[180477]: DHCPOFFER on 10.0.0.5 to 10:00:00:00:00:02 via eth0
Jan 27 11:49:19.427229 osdx dhcpd[180477]: DHCPDISCOVER from 10:00:00:00:00:02 via eth0
Jan 27 11:49:19.427262 osdx dhcpd[180477]: 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
Jan 27 11:49:20.828539 osdx systemd-journald[1949]: Runtime Journal (/run/log/journal/19d27b7fd9034c15b59c452d6ca2fcd4) is 1.8M, max 13.8M, 11.9M free.
Jan 27 11:49:20.830111 osdx systemd-journald[1949]: Received client request to rotate journal, rotating.
Jan 27 11:49:20.830170 osdx systemd-journald[1949]: Vacuuming done, freed 0B of archived journals from /run/log/journal/19d27b7fd9034c15b59c452d6ca2fcd4.
Jan 27 11:49:20.841219 osdx OSDxCLI[171716]: 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
Jan 27 11:49:20.828539 osdx systemd-journald[1949]: Runtime Journal (/run/log/journal/19d27b7fd9034c15b59c452d6ca2fcd4) is 1.8M, max 13.8M, 11.9M free.
Jan 27 11:49:20.830111 osdx systemd-journald[1949]: Received client request to rotate journal, rotating.
Jan 27 11:49:20.830170 osdx systemd-journald[1949]: Vacuuming done, freed 0B of archived journals from /run/log/journal/19d27b7fd9034c15b59c452d6ca2fcd4.
Jan 27 11:49:20.841219 osdx OSDxCLI[171716]: User 'admin' executed a new command: 'system journal clear'.
Jan 27 11:49:20.930454 osdx OSDxCLI[171716]: User 'admin' executed a new command: 'system journal show | tail'.
Jan 27 11:49:21.063096 osdx OSDxCLI[171716]: User 'admin' executed a new command: 'system journal show | tail'.
Jan 27 11:49:21.527138 osdx dhcpd[180533]: 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)
Jan 27 11:49:22.586820 osdx dhcpd[180533]: 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  2026/01/27 11:49:25  2026/01/27 23:49:25  2026/01/27 11:49:25