I have Kea set up in a Lab environment, about 100 subnets, using DHCP
helpers/relay to redirect traffic from other subnets to the DHCP server.
All of that is working great. But I just found out that if a system on
the same switch, in the same subnet as the DHCP server, attempts to get
a DHCP address, that request is ignored by Kea.
My original assumption was some network issue, but I used tcpdump to
watch for traffic from the client's MAC address and I saw packets
hitting the DHCP server. But nothing matching the MAC address of the
client was logged by Kea, and no reply traffic was ever sent. MAC below
slightly obfuscated.
[root@dhcp-2 kea]# tcpdump -vv -e ether host 11:22:74:25:e1:90
dropped privs to tcpdump
tcpdump: listening on eno16895np0, link-type EN10MB (Ethernet), snapshot
length 262144 bytes
10:14:37.975470 11:22:74:25:e1:90 (oui Unknown) > Broadcast, ethertype
IPv4 (0x0800), length 342: (tos 0x0, ttl 128, id 1879, offset 0, flags
[none], proto UDP (17), length 328)
0.0.0.0.bootpc > 255.255.255.255.bootps: [udp sum ok] BOOTP/DHCP,
Request from 8c:84:74:25:e1:90 (oui Unknown), length 300, xid
0x65cbc874, secs 12, Flags [Broadcast] (0x8000)
Client-Ethernet-Address 8c:84:74:25:e1:90 (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message (53), length 1: Discover
Client-ID (61), length 7: ether 8c:84:74:25:e1:90
Hostname (12), length 15: "WIN-SUC50U6GFQI"
Vendor-Class (60), length 8: "MSFT 5.0"
Parameter-Request (55), length 14:
Subnet-Mask (1), Default-Gateway (3), Domain-Name-Server
(6), Domain-Name (15)
Router-Discovery (31), Static-Route (33), Vendor-Option
(43), Netbios-Name-Server (44)
Netbios-Node (46), Netbios-Scope (47), Unknown (119),
Classless-Static-Route (121)
Classless-Static-Route-Microsoft (249), Unknown (252)
And nothing in the Kea log:
[root@dhcp-2 kea]# cat /var/log/kea/kea-dhcp4.log | grep e1\:90
[root@dhcp-2 kea]#
My subnet definitions list each subnet here, including the subnet
(Infrastructure) that the DHCP server and the client in question are in,
IPs below obfuscated
"subnet4": [
//Infrastructure
{ "id": 192168010,
"subnet": "192.168.10.0/24",
"pools": [ { "pool": "192.168.10.200 - 192.168.10.220" } ],
"option-data": [ { "name": "routers", "data": "192.168.10.254" }
] },
//Bench
{ "id": 192168002,
"subnet": "192.168.2.0/23",
"pools": [ { "pool": "192.168.3.50 - 192.168.3.249" } ],
"option-data": [ { "name": "routers", "data": "192.168.2.1" } ]
},
Two questions at this point, why isn't Kea logging anything regarding
the Discover request that is being ignored? If it couldn't be
processed, something should be logged? Second question, how to fix
things so that Kea can give the client in the Infrastructure subnet an
IP?
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