Kea DHCP Clients don't get ip's after migrating to KEA-dhcp from isc-dhcp

[ofh]

After migrating from ISC-DHCPv4 to KEA-DHCPv4 my clients don't get ipv4 addresses.
There also a lot of errors in the KEA-DHCP log:

WARN [kea-dhcp4.dhcpsrv.0x3a4a8725c008] DHCPSRV_OPEN_SOCKET_FAIL failed to open socket: Failed to open socket on interface em0_vlan160, reason: failed to bind fallback socket to address 10.1.160.1, port 67, reason: Address already in use - is another DHCP server running?

Running OPNsense 26.1.8_5-amd64

BR
OFH

[Monviech (Cedrik)]

Check which daemon is currently hogging port 67

# sockstat -l | grep -i :67

Example:

root@opn-dev-02:/src/git/core # sockstat -l | grep -i :67
root     kea-dhcp4   5875 24  udp4   192.168.30.1:67       *:*

[ofh]

Hi
Thanks for reply

Here is what I get when I use each DHCP-servers:

Only ISC-DHCP running
root@OPNsense-20:~ # sockstat -l | grep -i :67
dhcpd    dhcpd       7692 13  udp4   *:67                  *:*

Only Kea-DHCP running
root@OPNsense-20:~ # sockstat -l | grep -i :67
root     kea-dhcp4  22889 18  udp4   10.1.120.1:67         *:*
root     kea-dhcp4  22889 20  udp4   10.1.130.1:67         *:*
root     kea-dhcp4  22889 22  udp4   10.1.140.1:67         *:*
root     kea-dhcp4  22889 24  udp4   10.1.150.1:67         *:*
root     kea-dhcp4  22889 26  udp4   10.1.160.1:67         *:*

But only when Only Kea-DHCP is running, I get:
WARN [kea-dhcp4.dhcpsrv.0x3a4a8725c008] DHCPSRV_OPEN_SOCKET_FAIL failed to open socket: Failed to open socket on interface em0_vlan160, reason: failed to bind fallback socket to address 10.1.160.1, port 67, reason: Address already in use - is another DHCP server running?

[Monviech (Cedrik)]

But if we can see this while KEA runs it means it succeeded to bind

root     kea-dhcp4  22889 26  udp4   10.1.160.1:67         *:*

If you don't get IPs, maybe you had static ARP configured in ISC?
If that's the case, remove all static ARP configuration and reboot the firewall.

[dseven]

Possibly related: https://github.com/opnsense/core/issues/9743