Bug #16512
closed
Kea-DHCP4 throwing warning on Static IPWARN [kea-dhcp4.alloc-engine.0x18d8e0216d00] ALLOC_ENGINE_V4_DISCOVER_ADDRESS_CONFLICT
0%
Description
This is on my SG-5100 which is currently running 25.07.1-RELEASE (amd64), but from Reddit comments (see below) this has been around for a while.
I keep seeing:
WARN [kea-dhcp4.alloc-engine.0x18d8e0216d00] ALLOC_ENGINE_V4_DISCOVER_ADDRESS_CONFLICT
in my DHCP logs. The IP and MAC it warns about are assigned to this IP address: 192.168.20.248. Nothing else is on this IP address and the Address Pool for this interface. The DHCP pool is .30 to .230 so DHCP should not be assigning addresses in this range.
the complete error message is (MAC address and my domain replaced by X's):
WARN [kea-dhcp4.alloc-engine.0x18d8e0216d00] ALLOC_ENGINE_V4_DISCOVER_ADDRESS_CONFLICT [hwtype=1 d0:76:02:1b:18:6e], cid=[01:00:00:00:00:00:00], tid=0xc91c454d: conflicting reservation for address 192.168.20.248 with existing lease Address: 192.168.20.248 Valid life: 21600 Cltt: 1750997378 Hardware addr: XX:XX:XX:1b:18:6e Client id: 01:d0:76:02:1b:18:6e Subnet ID: 3 Pool ID: 0 State: default Relay ID: (none) Remote ID: (none) User context: { "Netgate": { "option-data": { "domain-name": "XXX.XXX" } } }
The problem with this is, THERE IS NOT a conflict and my DHCP logs are flooded with these errors, rending the log nearly useless (it is hard to find meaningful info when these errors show up every few minutes).
I poseted this to Reddit (see https://www.reddit.com/r/PFSENSE/comments/1lmwtys/keadhcp4_throwing_warning_on_static_ipwarn/) and was told this is long-standing KEA bug. Jim Thompson said that Netgate fixes FreeBSD bugs, but that was 4 months ago and no word.
Creating this bug so this can be addressed
Files
Updated by Rick Sayre 17 days ago
I had been observing similar behavior, and found what I believe may be a fix based on information from
https://kea.readthedocs.io/en/latest/arm/dhcp4-srv.html#using-client-identifier-and-hardware-address
Note that the cid and Client id do not match, with the cid being mostly zero.
Adding this to the top level DHCP Server Custom Configuration seems to have banished this warning:{"match-client-id": false}
Updated by Dennis Adler 16 days ago
Rick Sayre wrote in #note-1:
I had been observing similar behavior, and found what I believe may be a fix based on information from
https://kea.readthedocs.io/en/latest/arm/dhcp4-srv.html#using-client-identifier-and-hardware-address
Note that thecidandClient iddo not match, with thecidbeing mostly zero.Adding this to the top level DHCP Server Custom Configuration seems to have banished this warning:
{"match-client-id": false}
Rick, can you give more details on exactly where
{"match-client-id": false}
Goes? Is it in the Custom Configuration / JSON Configuration box at the bottom of the main DHCP 4 Server Settings screen? Unsure where else it might go, but wanted to hear from you before I try this. Thanks!
Updated by Rick Sayre 16 days ago
- File clipboard-202604071017-bxn18.png clipboard-202604071017-bxn18.png added
- File clipboard-202604071018-3akj4.png clipboard-202604071018-3akj4.png added
Yes, it goes in the Custom Configuration -> JSON Configuration box at the bottom of the main "Settings" tab for Services / DHCP Server / Settings
This will apply on all interfaces
You can also put it in that same box under a specific interface if you wish to narrow the scope; those details are on the docs referenced
FWIW, I do not believe this is a bug - it seems to be kea warning about a client identifier mismatch, and this behavior can be changed as described.
Updated by Dennis Adler 16 days ago
Thank you! I've entered this into my JSON Custom Config and cleared my DHCP logs. Hopefully those duplicate IP addr warnings will stop flooding the logs.
Updated by Dennis Adler 14 days ago
Dennis Adler wrote in #note-4:
Thank you! I've entered this into my JSON Custom Config and cleared my DHCP logs. Hopefully those duplicate IP addr warnings will stop flooding the logs.
Just checked my logs and all those DHCP conflict warnings are gone! Thank you for the fix, Rick!!!
Maybe Netgate will pick this up, as a patch if nothing else.
Updated by Jim Pingle 14 days ago
- File clipboard-202604090946-qyvgv.png clipboard-202604090946-qyvgv.png added
- Status changed from New to Not a Bug
- Priority changed from High to Normal
That setting is already a checkbox in the GUI for each interface:
Updated by Dennis Adler 14 days ago
Jim Pingle wrote in #note-6:
That setting is already a checkbox in the GUI for each interface:
Hi Jim,
Throwing away all Cliend IDs using this General Setting is overkill -- I assume the UID is Mac Address -- versus the simple fix Rick came up with. I use the Mac Addrs all the time when understanding which device is on which network. I simply wanted KEA to stop (erroneously) claiming their was a dup device on the network, when it is the same Mac Addr as the one I registered for a static address.
Updated by Jim Pingle 14 days ago
The value placed in the Kea configuration when checking that box is the same one suggested above. The effect is identical.
Updated by Dennis Adler 14 days ago
Jim Pingle wrote in #note-8:
The value placed in the Kea configuration when checking that box is the same one suggested above. The effect is identical.
Is KEA'e behavior per spec? I never had this problem with ISC DHCP. If this is still a bug, then ignoring the client ID is just a work around vs. a fix... right?
Updated by Jim Pingle 14 days ago
Kea is following the RFC, the clients are not sending the expected data consistently.