A server soyoustart with a proxmox Instance. The nethserver V7 and the samba4 AD for the user authentication are installed as a VM on this host. The difficulty comes that I want to protect the samba Container by the firewall of nethserver and I have no DHCP to assign the IP of eth0.

Another approach could be to use the firewall of proxmox and open each needed port to the VM, but you have to manage two firewall (the firewall of nethserver and the one of proxmox)

this is what I did at the end

when you want to create a green Interface on a server in a datacenter (that is not yours) you must create a 'dummy' interface in proxmox, this is how to create it.

and link your second card to it, only the VM which share this 'dummy' bridge can communicate each others, it is an internal network

this how to declare your two nics in proxmox, you can see the first nic on vbmr0, it will be the red interface( protected by the firewall of nethserver), the other will be used as the green interface, the samba4 AD container will use it

As you can see I set the virtual mac given by soyoustart in the settings of the eth0 nic (vmbr0), it is a mandatory if you want that your IP is routable.

Then now you can install NS7 by the console of proxmox, at the end your Virtual machine cannot reach internet, this is normal because in my use case, I have no DHCP to assign an IP to my server.

Go to the proxmox console of the VM, log as root then issue the following command, of course you must adjust to the good IP and gateway given by your provider

db networks setprop eth0 gateway xxx.xxx.xxx.xxx ipaddr xxx.xxx.xxx.xxx netmask 255.255.255.0
signal-event interface-update 

You can test if all is right by issuing in the VM

ip addr
ping 8.8.8.8
dig any google.fr
ping google.fr

It is possible that you are lost on which is the good NIC to configure, therefore either you can find it by the mac address you set in proxmox, or you can start to install nethserver with just one nic, then after create the new nic in proxmox, go to the server-manager configure this new nic to green, and set to red the eth0.