Hi,
I would like to understand why KEA allocates an IP which should not be
allocated.
I have, on purpose (for testing KEA behaviour), declared the following global
host reservation:
{
"boot-file-name": "",
"client-classes": [ ],
"hostname": "cs-test-1a",
"hw-address": "xx:xx:xx:xx:ff:3e",
"ip-address": "yyy.yyy.yyy.11",
"next-server": "0.0.0.0",
"option-data": [ ],
"server-hostname": "",
"user-context": {""}
},
IP address "yyy.yyy.yyy.11" is part of a subnet which is NOT configured in
kea-dhcp4.conf.
The client, with mac "xx:xx:xx:xx:ff:3e" , requests an IP from a subnet which
is correctly identified by KEA, KEA will first allocate the IP (although it
should not because it is not part fo that subnet), and then in a later step,
KEA will send a NACK.
See logs below.
My question is:
ISC DHCP would not do that.
ISC DHCP would allocate an IP from a pool of the selected subnet because the
reserved IP does not match.
Is it expected that KEA does not behave the same way ?
Is there any tuning that can be used so that KEA behaves the same way as ISC
DHCP used to behave ?
Thanks,
Veronique
logs:
# DISCOVER
2022-08-30 11:53:03.131 DEBUG [kea-dhcp4.packets/21553.140195413911744]
DHCP4_PACKET_RECEIVED [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info],
tid=0xa4a8ab1b: DHCPDISCOVER (type 1) received from my_router_ip to
my_kea_server_ip on interface enp3s0f0
2022-08-30 11:53:03.132 DEBUG [kea-dhcp4.packets/21553.140195413911744]
DHCP4_SUBNET_SELECTED [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info],
tid=0xa4a8ab1b: the subnet with ID 2887444672 was selected for client
assignments
2022-08-30 11:53:03.133 DEBUG [kea-dhcp4.alloc-engine/21553.140195413911744]
ALLOC_ENGINE_V4_DISCOVER_HR client [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info],
tid=0xa4a8ab1b sending DHCPDISCOVER has reservation for the address
yyy.yyy.yyy.11
# OFFER
2022-08-30 11:53:03.133 INFO [kea-dhcp4.leases/21553.140195413911744]
DHCP4_LEASE_ADVERT [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info], tid=0xa4a8ab1b:
lease yyy.yyy.yyy.11 will be advertised
2022-08-30 11:53:03.133 DEBUG [kea-dhcp4.options/21553.140195413911744]
DHCP4_PACKET_PACK [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info], tid=0xa4a8ab1b:
preparing on-wire format of the packet to be sent
2022-08-30 11:53:03.133 DEBUG [kea-dhcp4.packets/21553.140195413911744]
DHCP4_PACKET_SEND [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info], tid=0xa4a8ab1b:
trying to send packet DHCPOFFER (type 2) from my_kea_server_ip:67 to
my_router_ip:67 on interface enp3s0f0
# REQUEST
2022-08-30 11:53:03.608 DEBUG [kea-dhcp4.packets/21553.140195413911744]
DHCP4_PACKET_RECEIVED [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info],
tid=0xa4a8ab1b: DHCPREQUEST (type 3) received from my_router_ip to
my_kea_server_ip on interface enp3s0f0
2022-08-30 11:53:03.611 DEBUG [kea-dhcp4.packets/21553.140195413911744]
DHCP4_SUBNET_SELECTED [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info],
tid=0xa4a8ab1b: the subnet with ID 2887444672 was selected for client
assignments
2022-08-30 11:53:03.612 DEBUG [kea-dhcp4.alloc-engine/21553.140195413911744]
ALLOC_ENGINE_V4_REQUEST_ALLOC_REQUESTED [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no
info], tid=0xa4a8ab1b: trying to allocate requested address yyy.yyy.yyy.11
# ACK
2022-08-30 11:53:03.612 INFO [kea-dhcp4.leases/21553.140195413911744]
DHCP4_LEASE_ALLOC [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info], tid=0xa4a8ab1b:
lease yyy.yyy.yyy.11 has been allocated for 242 seconds
2022-08-30 11:53:03.613 DEBUG [kea-dhcp4.options/21553.140195413911744]
DHCP4_PACKET_PACK [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info], tid=0xa4a8ab1b:
preparing on-wire format of the packet to be sent
2022-08-30 11:53:03.613 DEBUG [kea-dhcp4.packets/21553.140195413911744]
DHCP4_PACKET_SEND [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info], tid=0xa4a8ab1b:
trying to send packet DHCPACK (type 5) from my_kea_server_ip:67 to
my_router_ip:67 on interface enp3s0f0
# 2nd REQUEST but this time subnet selection fails
2022-08-30 11:54:44.178 DEBUG [kea-dhcp4.packets/21553.140195413911744]
DHCP4_PACKET_RECEIVED [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info],
tid=0xa4a8ab1b: DHCPREQUEST (type 3) received from yyy.yyy.yyy.11 to
my_kea_server_ip on interface enp3s0f0
2022-08-30 11:54:44.180 DEBUG [kea-dhcp4.packets/21553.140195413911744]
DHCP4_SUBNET_SELECTION_FAILED [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info],
tid=0xa4a8ab1b: failed to select subnet for the client
2022-08-30 11:54:44.181 ERROR [kea-dhcp4.bad-packets/21553.140195413911744]
DHCP4_PACKET_NAK_0001 [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info],
tid=0xa4a8ab1b: failed to select a subnet for incoming packet, src
yyy.yyy.yyy.11, type DHCPREQUEST
# NACK
2022-08-30 11:54:44.181 DEBUG [kea-dhcp4.options/21553.140195413911744]
DHCP4_PACKET_PACK [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info], tid=0xa4a8ab1b:
preparing on-wire format of the packet to be sent
2022-08-30 11:54:44.181 DEBUG [kea-dhcp4.packets/21553.140195413911744]
DHCP4_PACKET_SEND [hwtype=1 xx:xx:xx:xx:ff:3e], cid=[no info], tid=0xa4a8ab1b:
trying to send packet DHCPNAK (type 6) from my_kea_server_ip:67 to
yyy.yyy.yyy.11:68 on interface enp3s0f0
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