[Kea-users] KEA not send a NAK when request ip is out of scope

Bob Harold rharolde at umich.edu
Thu Aug 29 13:17:07 UTC 2019


Only if the DHCP server is set to be "authoritative".  (At least in classic
DHCP, I assume Kea has a similar setting.)

If "authoritative" is not set, then the DHCP assumes there might be other
DHCP servers that could give an answer.

-- 
Bob Harold

On Thu, Aug 29, 2019 at 8:30 AM Thomas Andersen <than at itu.dk> wrote:

> Hi again,
>
>
>
> Sorry for bumping, but I’m sure there must be smart people out there who
> can guide me – you just missed my original email. :)
>
>
>
> But to make it a lot more simple:
>
> Shouldn’t KEA respond with NAK when client is requesting an IP out of
> configured scope?
>
>
>
> Br,
>
> Thomas
>
>
>
> *From: *Kea-users <kea-users-bounces at lists.isc.org> on behalf of Thomas
> Andersen <than at itu.dk>
> *Date: *Thursday, 22 August 2019 at 10.19
> *To: *"kea-users at lists.isc.org" <kea-users at lists.isc.org>
> *Subject: *[Kea-users] KEA not send a NAK when request ip is out of scope
>
>
>
> Hi,
>
>
>
> I got some problems with DHCP requests.
>
>
>
> Expected scenario:
>
> Computer logs on wifi with host login and is assigned to vlan 200 (
> 10.28.0.0/23)
>
> User logs into computer an reauthenticate on wifi and is assigned to vlan
> 201 (10.28.2.0/23)
>
> Windows 10 sends a DHCP request for the ip address on vlan 200.
>
> KEA sends a NAK, as the requested ip is not in scope.
>
> Windows sends DHCP discover and so forth.
>
>
>
> What we see is that KEA never sends the NAK, but sees the REQUEST packet
> as a bad packet, and then discards it.
>
> How can I get KEA to send a NAK?
>
> I’ve tried this with 1.3 and 1.5
>
>
>
> Log:
>
> 2019-08-21 13:40:24.683 DEBUG [kea-dhcp4.packets/41217]
> DHCP4_PACKET_RECEIVED [hwtype=1 a0:51:0b:0c:24:93],
> cid=[01:a0:51:0b:0c:24:93], tid=0xef9810de: DHCPREQUEST (type 3) received
> from 10.28.2.2 to 192.168.30.10 on interface eth0
>
> 2019-08-21 13:40:24.683 DEBUG [kea-dhcp4.packets/41217] DHCP4_QUERY_DATA
> [hwtype=1 a0:51:0b:0c:24:93], cid=[01:a0:51:0b:0c:24:93], tid=0xef9810de,
> packet details: local_address=192.168.30.10:67, remote_address=
> 10.28.2.2:67, msg_type=DHCPREQUEST (3), transid=0xef9810de,
>
> options:
>
>   type=012, len=008: "PC622019" (string)
>
>   type=050, len=004: 10.28.0.172 (ipv4-address)
>
>   type=053, len=001: 3 (uint8)
>
>   type=055, len=014: 1(uint8) 3(uint8) 6(uint8) 15(uint8) 31(uint8)
> 33(uint8) 43(uint8) 44(uint8) 46(uint8) 47(uint8) 119(uint8) 121(uint8)
> 249(uint8) 252(uint8)
>
>   type=060, len=008: "MSFT 5.0" (string)
>
>   type=061, len=007: 01:a0:51:0b:0c:24:93
>
>   type=81 (CLIENT_FQDN), flags: (N=0, E=0, O=0, S=0),
> domain-name='pc622019.itu.local' (partial)
>
> 2019-08-21 13:40:24.684 DEBUG [*kea-dhcp4.bad-packets*/41217]
> DHCP4_NO_LEASE_INIT_REBOOT [hwtype=1 a0:51:0b:0c:24:93],
> cid=[01:a0:51:0b:0c:24:93], tid=0xef9810de: no lease for address
> 10.28.0.172 requested by INIT-REBOOT client
>
>
>
> --
>
> Med venlig hilsen / With best regards
>
> Thomas Andersen
>
>
>
> Network Architect
>
>
>
> IT University of Copenhagen
>
> Rued Langgaards Vej 7
>
> 2300 København S
>
>
>
> Phone: +45 72185249
>
>
>
>
> ____________________________________________________________________________
>
>
>
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>
>
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