Local-Address

This scenario shows how to configure a DHCP relay agent to forward DHCP requests. By default, the local-address option uses a custom local IP as source address for upstream traffic.

../../../../_images/local.svg

Test DHCP Relay With Local-Address

Description

This example shows how to configure the local-address option. This command can be used to set the source address for upstream traffic.

Scenario

Step 1: Set the following configuration in DUT0 :

set interfaces dummy dum0 address 1.1.1.1/32
set interfaces ethernet eth0 vif 100 address 10.0.0.2/24
set interfaces ethernet eth1 vif 200 address 20.0.0.2/24
set service dhcp-relay INS downstream-interface eth1.200
set service dhcp-relay INS local-address 1.1.1.1
set service dhcp-relay INS server 10.0.0.1
set service dhcp-relay INS upstream-interface eth0.100
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'

Step 2: Set the following configuration in DUT1 :

set interfaces ethernet eth0 vif 100 address 10.0.0.1/24
set interfaces ethernet eth0 vif 100 traffic policy in LOGGER
set protocols static route 0.0.0.0/0 next-hop 10.0.0.2
set service dhcp-server shared-network dummy subnet 10.0.0.1/32
set service dhcp-server shared-network remote subnet 20.0.0.0/24 start 20.0.0.50 stop 20.0.0.50
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'
set traffic policy LOGGER rule 1 log prefix DHCP_
set traffic policy LOGGER rule 1 selector UDP
set traffic selector UDP rule 1 destination port 67
set traffic selector UDP rule 1 protocol udp

Step 3: Set the following configuration in DUT2 :

set interfaces ethernet eth0 vif 200 address dhcp
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'

Step 4: Ping IP address 10.0.0.1 from DUT0:

admin@DUT0$ ping 10.0.0.1 count 1 size 56 timeout 1
Show output
PING 10.0.0.1 (10.0.0.1) 56(84) bytes of data.
64 bytes from 10.0.0.1: icmp_seq=1 ttl=64 time=0.265 ms

--- 10.0.0.1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.265/0.265/0.265/0.000 ms

Step 5: Run command interfaces ethernet show at DUT2 and check if output contains the following tokens:

20.0.0.50
Show output
---------------------------------------------------------------------
  Name             IP Address           Admin  Oper  Vrf  Description
---------------------------------------------------------------------
    eth0  fe80::dcad:beff:feef:6c20/64  up     up
eth0.200  20.0.0.50/24                  up     up
          fe80::dcad:beff:feef:6c20/64
    eth1                                down   down

Step 6: Run command system journal show | cat at DUT1 and check if output matches the following regular expressions:

SRC=1.1.1.1 DST=10.0.0.1
Show output
Nov 12 16:04:03.000183 osdx systemd-timedated[312842]: Changed local time to Wed 2025-11-12 16:04:03 UTC
Nov 12 16:04:03.002079 osdx OSDxCLI[229492]: User 'admin' executed a new command: 'set date 2025-11-12 16:04:03'.
Nov 12 16:04:03.003419 osdx systemd-journald[1754]: Time jumped backwards, rotating.
Nov 12 16:04:03.303865 osdx systemd-journald[1754]: Runtime Journal (/run/log/journal/18feb8e5bb5a49edb7e456ab042ed98b) is 932.0K, max 6.5M, 5.6M free.
Nov 12 16:04:03.307386 osdx systemd-journald[1754]: Received client request to rotate journal, rotating.
Nov 12 16:04:03.307449 osdx systemd-journald[1754]: Vacuuming done, freed 0B of archived journals from /run/log/journal/18feb8e5bb5a49edb7e456ab042ed98b.
Nov 12 16:04:03.314079 osdx OSDxCLI[229492]: User 'admin' executed a new command: 'system journal clear'.
Nov 12 16:04:03.608554 osdx OSDxCLI[229492]: User 'admin' executed a new command: 'system coredump delete all'.
Nov 12 16:04:05.084894 osdx OSDxCLI[229492]: User 'admin' entered the configuration menu.
Nov 12 16:04:05.176971 osdx OSDxCLI[229492]: User 'admin' added a new cfg line: 'set interfaces eth0.100 address 10.0.0.1/24'.
Nov 12 16:04:05.252643 osdx OSDxCLI[229492]: User 'admin' added a new cfg line: 'set service dhcp-server shared-network dummy subnet 10.0.0.1/32'.
Nov 12 16:04:05.381320 osdx OSDxCLI[229492]: User 'admin' added a new cfg line: 'set service dhcp-server shared-network remote subnet 20.0.0.0/24 start 20.0.0.50 stop 20.0.0.50'.
Nov 12 16:04:05.485063 osdx OSDxCLI[229492]: User 'admin' added a new cfg line: 'set protocols static route 0.0.0.0/0 next-hop 10.0.0.2'.
Nov 12 16:04:05.599386 osdx OSDxCLI[229492]: User 'admin' added a new cfg line: 'set traffic policy LOGGER rule 1 log prefix DHCP_'.
Nov 12 16:04:05.717709 osdx OSDxCLI[229492]: User 'admin' added a new cfg line: 'set traffic policy LOGGER rule 1 selector UDP'.
Nov 12 16:04:05.835939 osdx OSDxCLI[229492]: User 'admin' added a new cfg line: 'set traffic selector UDP rule 1 protocol udp'.
Nov 12 16:04:05.912260 osdx OSDxCLI[229492]: User 'admin' added a new cfg line: 'set traffic selector UDP rule 1 destination port 67'.
Nov 12 16:04:06.039130 osdx OSDxCLI[229492]: User 'admin' added a new cfg line: 'set interfaces eth0.100 traffic policy in LOGGER'.
Nov 12 16:04:06.146780 osdx OSDxCLI[229492]: User 'admin' added a new cfg line: 'show working'.
Nov 12 16:04:06.236666 osdx ubnt-cfgd[319589]: inactive
Nov 12 16:04:06.331296 osdx INFO[319618]: FRR daemons did not change
Nov 12 16:04:06.359397 osdx kernel: 8021q: adding VLAN 0 to HW filter on device eth0
Nov 12 16:04:06.387888 osdx (udev-worker)[319667]: Network interface NamePolicy= disabled on kernel command line.
Nov 12 16:04:06.711823 osdx systemd[1]: Started dhcpd@main.service - "DHCP Server Service instance main".
Nov 12 16:04:06.714312 osdx cfgd[1453]: [229492]Completed change to active configuration
Nov 12 16:04:06.715033 osdx dhcpd[319761]: Wrote 0 leases to leases file.
Nov 12 16:04:06.730645 osdx OSDxCLI[229492]: User 'admin' committed the configuration.
Nov 12 16:04:06.739047 osdx dhcpd[319761]:
Nov 12 16:04:06.739054 osdx dhcpd[319761]: No subnet declaration for eth0 (no IPv4 addresses).
Nov 12 16:04:06.739057 osdx dhcpd[319761]: ** Ignoring requests on eth0.  If this is not what
Nov 12 16:04:06.739059 osdx dhcpd[319761]:    you want, please write a subnet declaration
Nov 12 16:04:06.739061 osdx dhcpd[319761]:    in your dhcpd.conf file for the network segment
Nov 12 16:04:06.739063 osdx dhcpd[319761]:    to which interface eth0 is attached. **
Nov 12 16:04:06.739066 osdx dhcpd[319761]:
Nov 12 16:04:06.759548 osdx dhcpd[319761]: Server starting service.
Nov 12 16:04:06.762432 osdx OSDxCLI[229492]: User 'admin' left the configuration menu.
Nov 12 16:04:07.481721 osdx dhcpd[319761]: DHCPDISCOVER from de:ad:be:ef:6c:20 via 20.0.0.2
Nov 12 16:04:07.483375 osdx kernel: [DHCP_-1] ACCEPT IN=eth0.100 OUT= MAC=de:ad:be:ef:6c:10:de:ad:be:ef:6c:00:08:00:45:00:01:48 SRC=1.1.1.1 DST=10.0.0.1 LEN=328 TOS=0x00 PREC=0x00 TTL=64 ID=51637 DF PROTO=UDP SPT=67 DPT=67 LEN=308
Nov 12 16:04:08.482592 osdx dhcpd[319761]: DHCPOFFER on 20.0.0.50 to de:ad:be:ef:6c:20 (osdx) via 20.0.0.2
Nov 12 16:04:08.483464 osdx dhcpd[319761]: DHCPREQUEST for 20.0.0.50 (10.0.0.1) from de:ad:be:ef:6c:20 (osdx) via 20.0.0.2
Nov 12 16:04:08.487365 osdx kernel: [DHCP_-1] ACCEPT IN=eth0.100 OUT= MAC=de:ad:be:ef:6c:10:de:ad:be:ef:6c:00:08:00:45:00:01:48 SRC=1.1.1.1 DST=10.0.0.1 LEN=328 TOS=0x00 PREC=0x00 TTL=64 ID=51756 DF PROTO=UDP SPT=67 DPT=67 LEN=308
Nov 12 16:04:08.498744 osdx dhcpd[319761]: DHCPACK on 20.0.0.50 to de:ad:be:ef:6c:20 (osdx) via 20.0.0.2