Netplan ID's with weird MAC Address in Windows DHCP Server

Bug #1759532 reported by purity on 2018-03-28
20
This bug affects 4 people
Affects Status Importance Assigned to Milestone
netplan
Undecided
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Bug Description

I installed an Ubuntu Server 17.10 to an ESXi 6.5 host with the VMXNET3 adapter.

I'm running our DHCP on a Windows Server 2012.

When the VM connects to the DHCP the DHCP server get a very weird MAC address from the server, like this,

9f6e852400020000ab11d45377acf56c2312

But the MAC address on the VM in vCenter looks all normal.

I have also tried with another adapter, E1000E but still the same weirdness.

netplan config file.

/etc/netplan/01-netcfg.yaml

# This file describes the network interfaces available on your system
# For more information, see netplan(5).
network:
  version: 2
  renderer: networkd
  ethernets:
    ens160:
      dhcp4: yes
      dhcp6: no

When I disabled netplan through /etc/default/grub with the following line,
GRUB_CMDLINE_LINUX="ipv6.disable=1 netcfg/do_not_use_netplan=true"

and also renamed the /etc/netplan/01-netcfg.yaml to /etc/netplan/01-netcfg.yaml.bak

and configured the old interfaces file,

/etc/network/interfaces

# /etc/network/interfaces -- configuration file for ifup(8), ifdown(8)
# Generated by debian-installer.

# The loopback interface
auto lo
iface lo inet loopback
auto ens160
iface ens160 inet dhcp

and untagged the following line in /etc/default/networking
CONFIGURE_INTERFACES=yes

it works as it should, the DHCP server get's the right MAC address and I can use my reservation.

Ryan Harper (raharper) wrote :

I believe you are seeing a DHCP Client Identifier instead MAC address; netplan's
networkd backend defaults to using this as the client ID instead of MAC.

I think you want to switch to using MAC as the DHCP client id:

[DHCP]
ClientIdentifier=mac

https://askubuntu.com/questions/987673/how-to-get-netplan-on-17-10-server-to-work-with-a-windows-server-dhcp-server

purity (purity82) wrote :

Where should I put that configuration line? It was not so clear in the askubuntu question.

Can't I have some configuration line in the .yaml file for netplan to use MAC instead of that Client Identifier?

Thanks.

Ryan Harper (raharper) wrote :

You shouldn't have to know where to put the networkd config which is exactly the point of the original bug; when bug #1738998 is resolved, it will include information on what configuration to put in the netplan yaml to enable MAC as DHCP Client Identifier.

In the meantime you can:

1) cp /run/systemd/network/10-netplan-ens160.network /etc/systemd/network/
2) update /etc/systemd/network/10-netplan-ens160.network to add in ClientIdentifier=mac under the [DHCP] section
3) systemctl restart systemd-networkd

purity (purity82) wrote :

Thanks, that worked fine. =)

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