Bug#982356: Testing Vagrant box shows unexpected IP address after first vagrant up

[Johan Mazel <johan.mazel@ssi.gouv.fr>]

Package: cloud.debian.org
Version: 20210207.1

When I specify an additional interface using 'testing.vm.network
"private_network", name: "my_network", ip: "10.249.10.10", :mac =>
"000000001010"' and I perform "vagrant up", there are two interfaces on
the host named testing.
One interface has an IP address inside the 192.168.121.0/24 network.
The other interface has two IP addresses: the specified 10.249.10.10 IP
address and another IP address inside the 10.249.10.0/24 network.
This second IP address disappears after "vagrant reload".

I attached a Vagrantfile to this email.
One can type these commands to check that two addresses are indeed added
to interface ens6:
$ vagrant up
$ vagrant ssh testing
$ ip a show ens6

Some tools (such as openvpn) do not like that the second interface
(ens6) has two IP addresses.
I suggest that the DHCP provided IP address be removed once the IP
address specified in the Vagrantfile is setup.

I am using Debian Buster, kernel 5.9.0-5-amd64, libc6 2.28-10, vagrant
2.2.3 et libvirt 5.0.0-4+deb10u1.
Les données à caractère personnel recueillies et traitées dans le cadre de cet échange, le sont à seule fin d’exécution d’une relation professionnelle et s’opèrent dans cette seule finalité et pour la durée nécessaire à cette relation. Si vous souhaitez faire usage de vos droits de consultation, de rectification et de suppression de vos données, veuillez contacter contact.rgpd@sgdsn.gouv.fr. Si vous avez reçu ce message par erreur, nous vous remercions d’en informer l’expéditeur et de détruire le message. The personal data collected and processed during this exchange aims solely at completing a business relationship and is limited to the necessary duration of that relationship. If you wish to use your rights of consultation, rectification and deletion of your data, please contact: contact.rgpd@sgdsn.gouv.fr. If you have received this message in error, we thank you for informing the sender and destroying the message.

# -*- mode: ruby -*-
# vi: set ft=ruby :

Vagrant.configure("2") do |config|    
  config.vm.define "testing" do |testing|
    testing.vm.box = "debian/testing64"
    testing.vm.box_version = "20210124.1"
    testing.vm.hostname = "testing"
    testing.vm.network "private_network", name: "my_network", ip: "10.249.10.10", :mac => "000000001010"
    
    testing.vm.synced_folder ".", "/vagrant", type: "rsync", rsync__exclude: ".git/"
  end
end