Proxmox VE 8 - DHCP not working on Containers

[feliceM]

Hi there,
I have updated Proxmox a couple of days ago and it is now on version 8.03
I have several VMs which are working fine with DHCP set
I have two containers, one was already installed when Proxmox was in version 7.x which was working with DHCP and one new installed today on version 8.03.
The containers are running Ubuntu 20.04.6 LTS
Both containers do not get the IP when DHCP mode is selected. Both of them work fine with static IP.

I would appreciate som help to identify the issue and get the containers working with DHCP.

 

[alex#]

When you restart the container with DHCP enabled, what's the output inside the container of:

journalctl --boot --no-pager _COMM=dhclient

 

[Spoonman2002]

- Can the two containers ping the DHCP server?
- are you using DHCP reservation, in that case check if the MAC addresses are correct

 

[feliceM]

Thank you for pointing in the right direction. I did run journalctl --boot --no-pager _COMM=dhclient and I think I understand what is happening.

root@testIP:~# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0@if51: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 8e:ac:ed:2e:ec:75 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet6 fe80::8cac:edff:fe2e:ec75/64 scope link
       valid_lft forever preferred_lft forever
root@testIP:~# journalctl --boot --no-pager _COMM=dhclient
Jul 04 04:32:46 testIP ifup[101]: Internet Systems Consortium DHCP Client 4.4.3-P1
Jul 04 04:32:46 testIP ifup[101]: Copyright 2004-2022 Internet Systems Consortium.
Jul 04 04:32:46 testIP ifup[101]: All rights reserved.
Jul 04 04:32:46 testIP ifup[101]: For info, please visit https://www.isc.org/software/dhcp/
Jul 04 04:32:46 testIP dhclient[101]: Internet Systems Consortium DHCP Client 4.4.3-P1
Jul 04 04:32:46 testIP dhclient[101]: Copyright 2004-2022 Internet Systems Consortium.
Jul 04 04:32:46 testIP dhclient[101]: All rights reserved.
Jul 04 04:32:46 testIP dhclient[101]: For info, please visit https://www.isc.org/software/dhcp/
Jul 04 04:32:46 testIP dhclient[101]:
Jul 04 04:32:46 testIP ifup[101]: Listening on LPF/eth0/8e:ac:ed:2e:ec:75
Jul 04 04:32:46 testIP ifup[101]: Sending on   LPF/eth0/8e:ac:ed:2e:ec:75
Jul 04 04:32:46 testIP ifup[101]: Sending on   Socket/fallback
Jul 04 04:32:46 testIP ifup[101]: Created duid "\000\001\000\001,6]n\216\254\355.\354u".
Jul 04 04:32:46 testIP dhclient[101]: Listening on LPF/eth0/8e:ac:ed:2e:ec:75
Jul 04 04:32:46 testIP dhclient[101]: Sending on   LPF/eth0/8e:ac:ed:2e:ec:75
Jul 04 04:32:46 testIP dhclient[101]: Sending on   Socket/fallback
Jul 04 04:32:46 testIP dhclient[101]: Created duid "\000\001\000\001,6]n\216\254\355.\354u".
Jul 04 04:32:46 testIP dhclient[101]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 4
Jul 04 04:32:46 testIP ifup[101]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 4
Jul 04 04:32:50 testIP dhclient[101]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 9
Jul 04 04:32:50 testIP ifup[101]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 9
Jul 04 04:32:59 testIP dhclient[101]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 15
Jul 04 04:32:59 testIP ifup[101]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 15
Jul 04 04:33:14 testIP dhclient[101]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 16
Jul 04 04:33:14 testIP ifup[101]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 16
Jul 04 04:33:30 testIP dhclient[101]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 16
Jul 04 04:33:30 testIP ifup[101]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 16
Jul 04 04:33:46 testIP dhclient[101]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 1
Jul 04 04:33:46 testIP ifup[101]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 1
Jul 04 04:33:47 testIP dhclient[101]: No DHCPOFFERS received.
Jul 04 04:33:47 testIP ifup[101]: No DHCPOFFERS received.
Jul 04 04:33:47 testIP ifup[101]: No working leases in persistent database - sleeping.
Jul 04 04:33:47 testIP dhclient[101]: No working leases in persistent database - sleeping.
root@testIP:~#

Is the router DHCP server running out of IP?
I will try to enlarge the pool on the Vlan to test if the issue disappear.

 

[alex#]

Is the router DHCP server running out of IP?

That's possible, check the log there for something like 'no free leases'.

A faulty firewall configuration can also be another reason (https://pve.proxmox.com/pve-docs/pve-admin-guide.html#chapter_pve_firewall).