NethServer Version: 7.5.1804 fina (subscription)
Module: ???
After a powerfault my system has a strange behavior.
I have 4 external IP xxx.xxx.xxx.18/19/20/21 subnet 255.255.255.248 or CDIR 29.
The address 18 was assigned to the red interface of my NS. Today I had probems with internet connection. I changed the IP to 20 and all went fine again.
BUT: even there is no NIC with the adress 18, I can still ping it. 
There should be no interface with this address. When I shut down this instance I can’t ping adress 18 or 20 from proxmox shell. When I start the instance again, I can ping both again.
Only 2 NIC are assigned to this instance and present. One green and one red. As the servermanager is present, the green NIC is o.k.
db networks show shows no entry with adress 18.
ifconfig shows no entry with adress 18.
brctl shows no NIC with address 18.
When I try to assign adress 18 to red NIC I get a failure. In log I find “some other host already uses this address”. Is it possible that somehow a “ghost-interface” was created?
I’m running out of ideas how to investigate which host or NIC this is?
Can some one help me please?
TIA