Kea DHCPv4 fails to start after OPNsense 26.1.6 upgrade (interface not running d

[fengchen_opn]

Hi,

After upgrading to OPNsense 26.1.6, I'm experiencing issues where Kea DHCPv4 does not start properly and clients fail to obtain IP addresses.

**Environment:**

* OPNsense 26.1.6
* LAN interface: re0 (192.168.50.1/24)
* AP: TP-Link (bridge mode, no DHCP)
* DHCP server: Kea DHCPv4

This setup was previously running ISC DHCPd without any issues.

---

**Observed behavior:**

From the logs, it looks like Kea attempts to start while the LAN interface is not yet up:

```
DHCPSRV_OPEN_SOCKET_FAIL failed to open socket: the interface re0 is not running
DHCP4_OPEN_SOCKETS_FAILED maximum number of open service sockets attempts: 0, has been exhausted without success
```

Shortly after that, the interface comes up:

```
re0: link state changed to UP
```

Code Select Expand

2026-03-28T14:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MEMFILE_LFC_EXECUTE executing Lease File Cleanup using: /usr/local/sbin/kea-lfc -4 -x /var/db/kea/kea-leases4.csv.2 -i /var/db/kea/kea-leases4.csv.1 -o /var/db/kea/kea-leases4.csv.output -f /var/db/kea/kea-leases4.csv.completed -p /var/db/kea/kea-leases4.csv.pid -c ignored-path
2026-03-28T14:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MEMFILE_LFC_START starting Lease File Cleanup
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcp4.0x529759e5c008] DHCP4_DYNAMIC_RECONFIGURATION_SUCCESS dynamic server reconfiguration succeeded with file: /usr/local/etc/kea/kea-dhcp4.conf
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcp4.0x529759e5c008] DHCP4_MULTI_THREADING_INFO enabled: yes, number of threads: 4, queue size: 64
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_CFGMGR_USE_ALLOCATOR using the iterative allocator for V4 leases in subnet 192.168.50.0/24
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcp4.0x529759e5c008] DHCP4_OPEN_SOCKETS_FAILED maximum number of open service sockets attempts: 0, has been exhausted without success
2026-03-28T13:47:33 Warning kea-dhcp4 WARN  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_OPEN_SOCKET_FAIL failed to open socket: the interface re0 is not running
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MEMFILE_LFC_SETUP setting up the Lease File Cleanup interval to 3600 sec
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MEMFILE_EXTRACT_EXTENDED_INFO4 extracting extended info saw 3 leases, extended info sanity checks modified 0 / updated 0 leases and 0 leases have relay or remote id
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MEMFILE_LEASE_FILE_LOAD loading leases from file /var/db/kea/kea-leases4.csv
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MEMFILE_LEASE_FILE_LOAD loading leases from file /var/db/kea/kea-leases4.csv.2
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MEMFILE_DB opening memory file lease database: persist=true type=memfile universe=4
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcp4.0x529759e5c008] DHCP4_CONFIG_COMPLETE DHCPv4 server has completed configuration: added IPv4 subnets: 1; DDNS: disabled
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.database.0x529759e5c008] CONFIG_BACKENDS_REGISTERED the following config backend types are available:
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_FORENSIC_BACKENDS_REGISTERED the following forensic backend types are available:
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.hosts.0x529759e5c008] HOSTS_BACKENDS_REGISTERED the following host backend types are available:
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_LEASE_MGR_BACKENDS_REGISTERED the following lease backend types are available: memfile
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_CFGMGR_ADD_IFACE listening on interface wg1
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_CFGMGR_ADD_IFACE listening on interface re0
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_CFGMGR_SOCKET_TYPE_SELECT using socket type raw
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_CFGMGR_SOCKET_TYPE_SELECT using socket type raw
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_CFGMGR_NEW_SUBNET4 a new subnet has been added to configuration: 192.168.50.0/24 with params: valid-lifetime=7200
2026-03-28T13:47:33 Warning kea-dhcp4 WARN  [kea-dhcp4.dhcp4.0x529759e5c008] DHCP4_RESERVATIONS_LOOKUP_FIRST_ENABLED Multi-threading is enabled and host reservations lookup is always performed first.
2026-03-28T13:47:33 Warning kea-dhcp4 WARN  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MT_DISABLED_QUEUE_CONTROL disabling dhcp queue control when multi-threading is enabled.
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.commands.0x529759e5c008] COMMAND_RECEIVED Received command 'config-set'
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcp4.0x529759e5c008] DHCP4_DYNAMIC_RECONFIGURATION initiate server reconfiguration using file: /usr/local/etc/kea/kea-dhcp4.conf, after receiving SIGHUP signal or config-reload command
2026-03-28T13:47:33 Informational kea-dhcp4 INFO  [kea-dhcp4.commands.0x529759e5c008] COMMAND_RECEIVED Received command 'config-reload'

2026-03-28T13:47:35 Notice opnsense /usr/local/etc/rc.linkup: DEVD: Ethernet attached event for lan(re0)
2026-03-28T13:47:35 Notice kernel <6>[55] re0: link state changed to UP
2026-03-28T13:47:33 Warning opnsense /usr/local/etc/rc.newwanipv6: warning: ignoring missing default tunable request: hw.ibrs_disable
2026-03-28T13:47:33 Warning opnsense /usr/local/etc/rc.newwanipv6: warning: ignoring missing default tunable request: vm.pmap.pti
-
2026-03-28T13:47:33 Notice kernel <118>[53]
2026-03-28T13:47:33 Notice kernel <118>[53]  wg (wg1)        -> v4: 10.0.0.1/24
2026-03-28T13:47:33 Notice kernel <118>[53]                     v6/DHCP6: 2-:-:-:98cf:-:-:fe03:3852/64
2026-03-28T13:47:33 Notice kernel <118>[53]  WAN (pppoe0)    -> v4/PPPoE: 2-.-.10.181/32
2026-03-28T13:47:33 Notice kernel <118> LAN (re0)       -> v4: 192.168.50.1/24
2026-03-28T13:47:33 Notice kernel <118>[53]
2026-03-28T13:47:33 Notice kernel <118>*** OPNsense.localdomain: OPNsense 26.1.5 (amd64) ***
2026-03-28T13:47:33 Notice kernel <118>[53]
2026-03-28T13:47:32 Notice kernel <118>[53] Sat Mar 28 13:47:32 CST 2026
2026-03-28T13:47:32 Notice kernel <118>[53] Root file system: /dev/gpt/rootfs
2026-03-28T13:47:32 Notice opnsense /usr/local/etc/rc.linkup: DEVD: Ethernet detached event for lan(re0)
2026-03-28T13:47:32 Notice opnsense /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : unbound_configure_do(,[wan,lan]))
2026-03-28T13:47:32 Notice opnsense /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : openssh_configure_do(,[wan,lan]))
2026-03-28T13:47:32 Notice opnsense /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : opendns_configure_do())
2026-03-28T13:47:32 Notice kernel <6>[52] re0: link state changed to DOWN
2026-03-28T13:47:31 Notice opnsense /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : ntpd_configure_do())
2026-03-28T13:47:31 Notice opnsense /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (execute task : dhcrelay_configure_if(,[wan,lan],inet6))
2026-03-28T13:47:31 Notice opnsense /usr/local/etc/rc.newwanipv6: plugins_configure newwanip (,[wan,lan],inet6)
2026-03-28T13:47:31 Notice opnsense /usr/local/etc/rc.newwanipv6: plugins_configure vpn (execute task : wireguard_configure_do())
2026-03-28T13:47:31 Notice opnsense /usr/local/etc/rc.newwanipv6: plugins_configure vpn (execute task : openvpn_configure_do(,[wan,lan]))
2026-03-28T13:47:31 Notice opnsense /usr/local/etc/rc.newwanipv6: plugins_configure vpn (execute task : ipsec_configure_do(,[wan,lan]))
2026-03-28T13:47:31 Notice opnsense /usr/local/etc/rc.newwanipv6: plugins_configure vpn (,[wan,lan],inet6)
2026-03-28T13:47:31 Notice kernel <118>[51] >>> Invoking start script 'beep'
2026-03-28T13:47:31 Notice kernel <118>[51] Service `sysctl' has been restarted.

2026-03-28T13:47:27 Informational kea-dhcp4 INFO  [kea-dhcp4.leases.0x529759e6b808] DHCP4_LEASE_OFFER [hwtype=1 *:*:*:d4:24:b5], cid=[01:*:*:*:d4:24:b5], tid=0x44cc464a: lease 192.168.50.200 will be offered
2026-03-28T13:47:27 Informational kea-dhcp4 INFO  [kea-dhcp4.packets.0x529759e6b808] DHCP4_PACKET_RECEIVED [hwtype=1 *:*:*:d4:24:b5], cid=[01:*:*:*:d4:24:b5], tid=0x44cc464a: DHCPDISCOVER (type 1) received from 0.0.0.0 to 255.255.255.255 on interface re0
2026-03-28T13:47:27 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcp4.0x529759e6b808] DHCP4_QUERY_LABEL received query: [hwtype=1 *:*:*:d4:24:b5], cid=[01:*:*:*:d4:24:b5], tid=0x44cc464a
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcp4.0x529759e5c008] DHCP4_STARTED Kea DHCPv4 server version 3.0.2 started
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcp4.0x529759e5c008] DHCP4_MULTI_THREADING_INFO enabled: yes, number of threads: 4, queue size: 64
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_CFGMGR_USE_ALLOCATOR using the iterative allocator for V4 leases in subnet 192.168.50.0/24
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MEMFILE_LFC_SETUP setting up the Lease File Cleanup interval to 3600 sec
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MEMFILE_EXTRACT_EXTENDED_INFO4 extracting extended info saw 3 leases, extended info sanity checks modified 0 / updated 0 leases and 0 leases have relay or remote id
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MEMFILE_LEASE_FILE_LOAD loading leases from file /var/db/kea/kea-leases4.csv
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MEMFILE_LEASE_FILE_LOAD loading leases from file /var/db/kea/kea-leases4.csv.2
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MEMFILE_DB opening memory file lease database: persist=true type=memfile universe=4
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcp4.0x529759e5c008] DHCP4_CONFIG_COMPLETE DHCPv4 server has completed configuration: added IPv4 subnets: 1; DDNS: disabled
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.database.0x529759e5c008] CONFIG_BACKENDS_REGISTERED the following config backend types are available:
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_FORENSIC_BACKENDS_REGISTERED the following forensic backend types are available:
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.hosts.0x529759e5c008] HOSTS_BACKENDS_REGISTERED the following host backend types are available:
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_LEASE_MGR_BACKENDS_REGISTERED the following lease backend types are available: memfile
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.commands.0x529759e5c008] COMMAND_ACCEPTOR_START Starting to accept connections via unix domain socket bound to /var/run/kea/kea4-ctrl-socket
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_CFGMGR_ADD_IFACE listening on interface wg1
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_CFGMGR_ADD_IFACE listening on interface re0
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_CFGMGR_SOCKET_TYPE_SELECT using socket type raw
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_CFGMGR_SOCKET_TYPE_SELECT using socket type raw
2026-03-28T13:47:26 Informational kea-dhcp4 INFO  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_CFGMGR_NEW_SUBNET4 a new subnet has been added to configuration: 192.168.50.0/24 with params: valid-lifetime=7200
2026-03-28T13:47:26 Warning kea-dhcp4 WARN  [kea-dhcp4.dhcp4.0x529759e5c008] DHCP4_RESERVATIONS_LOOKUP_FIRST_ENABLED Multi-threading is enabled and host reservations lookup is always performed first.
2026-03-28T13:47:26 Warning kea-dhcp4 WARN  [kea-dhcp4.dhcpsrv.0x529759e5c008] DHCPSRV_MT_DISABLED_QUEUE_CONTROL disabling dhcp queue control when multi-threading is enabled.

2026-03-28T13:47:26 Notice kernel <118>[46] INFO/keactrl: Starting /usr/local/sbin/kea-dhcp4 -c /usr/local/etc/kea/kea-dhcp4.conf
2026-03-28T13:47:26 Notice kernel <118>[46] Starting kea.
2026-03-28T13:47:26 Notice kernel <118>[46] Sync KEA DHCP config...done.

2026-03-28T13:47:10 Notice kernel ---<<BOOT>>---

Thanks.

[newsense]

There should be no need for Kea to run on a WireGuard interface. Did you try deselecting  it in the settings ?

[Monviech (Cedrik)]

re0 looks more like our most endearing friend and helper Realtek(/s)

[fengchen_opn]

There should be no need for Kea to run on a WireGuard interface. Did you try deselecting  it in the settings ?

The re0 interface is configured as LAN

[nero355]

After upgrading to OPNsense 26.1.6

Are you from the future ?

;)



/Could not resist... ^_^

[Monviech (Cedrik)]

I read a bit through the KEA mailing list and this looks related:

https://lists.isc.org/pipermail/kea-users/2026-March/006027.html