I have recently had to replace my motherboard (don't ask, if you don't want to see a grow-up cry ;-) ) New motherboard -> new ethernet -> new MAC address -> new IP address via DHCP. As I had a fixed IP address 172.16.0.1 assigned to this host, the newly assigned IP address 172.16.210.213 doesn't fit, so I quickly changed the entry on my DHCP server (a Zyxel 5501 router) to reflect the new MAC address of the machine and rebooted but ... the machine got the bad IP address assigned again. It tried various things, eg deleting entries on my router, deleting various dhcp-related files on my machine, restarting, stopping, deleting lease files, restarting ... all to no avail I now restarted the dhclient with "-d" to see what happens and the debug output shows
Listening on LPF/virbr0-nic/52:54:00:28:48:36
Sending on LPF/virbr0-nic/52:54:00:28:48:36
Listening on LPF/virbr0/52:54:00:28:48:36
Sending on LPF/virbr0/52:54:00:28:48:36
Listening on LPF/wlp8s0/28:b2:bd:f8:1f:bf
Sending on LPF/wlp8s0/28:b2:bd:f8:1f:bf
Listening on LPF/eno1/40:8d:5c:b7:02:a0
Sending on LPF/eno1/40:8d:5c:b7:02:a0
Sending on Socket/fallback
DHCPDISCOVER on virbr0-nic to 255.255.255.255 port 67 interval 3 (xid=0xbedfb46e)
DHCPDISCOVER on virbr0 to 255.255.255.255 port 67 interval 3 (xid=0x7c063c6f)
DHCPDISCOVER on wlp8s0 to 255.255.255.255 port 67 interval 3 (xid=0x139d1c0c)
send_packet: Network is down
dhclient.c:2098: Failed to send 300 byte long packet over wlp8s0 interface.
DHCPREQUEST of 172.16.0.1 on eno1 to 255.255.255.255 port 67 (xid=0x112759d7)
receive_packet failed on wlp8s0: Network is down
DHCPNAK from 172.16.255.254 (xid=0xd7592711)
/etc/resolvconf/update.d/libc: Warning: /etc/resolv.conf is not a symbolic link to /run/resolvconf/resolv.conf
DHCPDISCOVER on eno1 to 255.255.255.255 port 67 interval 3 (xid=0xaa7e090e)
DHCPDISCOVER on wlp8s0 to 255.255.255.255 port 67 interval 3 (xid=0x139d1c0c)
send_packet: Network is down
dhclient.c:2098: Failed to send 300 byte long packet over wlp8s0 interface.
DHCPDISCOVER on virbr0-nic to 255.255.255.255 port 67 interval 7 (xid=0xbedfb46e)
DHCPDISCOVER on virbr0 to 255.255.255.255 port 67 interval 7 (xid=0x7c063c6f)
DHCPREQUEST of 172.16.210.213 on eno1 to 255.255.255.255 port 67 (xid=0xe097eaa)
DHCPOFFER of 172.16.210.213 from 172.16.255.254
DHCPACK of 172.16.210.213 from 172.16.255.254
So, I assume that the dhclient gets this bad address from somewhere and requests this bad address from the router who graciously assigns it to him. But I can't, for the heck of it, find out where this bad IP address is stored! How can I convince my machine to request 172.16.0.1 and not 172.16.210.213?
I'm currently running Kubuntu 16.04 and ... yes, I know it's outdated, an upgrade is in the works.
dhclient
gets the the bad IP address from to request it from the DHCP server on the router.