DHCP seems not functioning to show leases

UCS - Univention Corporate Server
#1

have configured DHCP server on univention (DHCP really needs some TLC)
we have various subnets on different vlans, which ALL use a “RELAY” & DHCP 82 from the specific vlan to the univention.(in the core)
then there is a FW rule to allow the reply from the univention back to the specific vlan.
there is NO mappings for the seperate vlans tied to network cards on the univention server.

it shows any lease issued to Vlan1… 100% cannot fault it.
and it updates for every other computer on the system.

root@dc02:~# dhcp-lease-list --lease /var/lib/dhcp/dhcpd.leases
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = (unset),
	LC_ALL = (unset),
	LC_CTYPE = "UTF-8",
	LANG = "en_HK.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to a fallback locale ("en_HK.UTF-8").
Reading leases from /var/lib/dhcp/dhcpd.leases
MAC                IP              hostname       valid until         manufacturer        
====================================================================
28:00:af:8e:f1:ca  172.18.0.224            
3c:06:30:18:1f:69  172.18.0.229     
64:5d:86:f7:c7:54  172.18.0.214 
78:2b:cb:8c:6e:50  172.18.0.219         
7a:06:ab:7b:63:af  172.18.0.215                  
84:94:37:bf:d5:51  172.18.0.227    
98:5a:eb:dc:34:63  172.18.0.223        
a4:bb:6d:97:78:e5  172.18.0.228   
ac:bc:32:90:03:b7  172.18.0.211    
bc:d0:74:34:c9:0b  172.18.0.222   
cc:08:fa:81:ba:9f  172.18.0.221

but it also issues DHCP to other vlans, again cannot fault it…

Aug 7 12:57:12 dc02 dhcpd[19347]: reuse_lease: lease age 397 (secs) under 25% threshold, reply with unaltered, existing lease for 10.10.100.50
Aug 7 12:57:12 dc02 dhcpd[19347]: DHCPREQUEST for 10.10.100.50 from ac:bc:32:90:03:b7 ( via 10.10.100.2
Aug 7 12:57:12 dc02 dhcpd[19347]: DHCPACK on 10.10.100.50 to ac:bc:32:90:03:b7via 10.10.100.2

but… if we look at the lease for this mac ac:bc:32:90:03:b7 it shows “172.18.0.211”
now if the DHCP server issues the lease , why does it show a vlan1 lease. ip address?
even if teh computer was connected on that wifi point previously, it should STILL show multiple DHCP leases for that mac, but with different subnets, until the unused ones time out.

everything works… no connectivity issues

unify WIFI even shows correct info:

ac:bc:32:90:03:b7 10.10.100.50

we have both the DHCPREQUEST AND more importantly the DHCPACK BACK showing on the univention
so it should be showing in the lease file.

#2

Ahhh. its a bug…
if we go into the lease file and delete the vlan1 mapping , then save the result back
as soon as we look at teh file again…
we get:

ac:bc:32:90:03:b7  10.10.100.50

which is then working correctly.

clearly the logic was too complicated for the programmer since they would have to map multiple ip addresses to the same MAC addresses, handling for each subnet coming into the DHCP then cross check the subnets.

but really if the same mac comes in again they should delete any current ip addresses for that mac.
not be having “hidden” leases based on different vlans

actually that might be a serious bug, where you have a setup for vlan per computer over wifi for some radius setups, or if you have multiple vlan for SSID mapping and the user can flip between the vlans and have DHCP relay

you wil get ip address hiding.

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