Configure an additional IP and its virtual MAC in Proxmox

Every virtual machine intended to be directly reachable from the Internet must have a consistent network configuration. On a By-Hoster VDS, an additional IP is delivered with a dedicated virtual MAC that is locked on the network.

Why does each additional IP have its own MAC?

You do not choose a MAC at random, nor do you keep the one generated automatically by Proxmox. On the VM’s network adapter, you must select the MAC supplied for the IP concerned.

• one additional IP = one dedicated virtual MAC;
• one IP/MAC pair = a single active network adapter at a time;
• never duplicate an IP or a MAC across several VMs;
• do not replace the VDS’s primary management IP with a guest IP.

An incorrect pair can result in a complete loss of connectivity or a network security block.

How do I order an additional IP for my VDS?

From your service’s Network tab, using the button for ordering and managing additional IPs.

1. Log in to the By-Hoster customer area.
2. Open My services, then your Proxmox VDS.
3. Go to the Network tab.
4. Click the button for ordering/managing additional IPs.
5. Change the option on your plan and confirm the order or any resulting invoice.
6. Wait until the IP is shown as active before using it.

The maximum number of IPs depends on the plan. The Network screen displays the number already assigned and the available limit.

Which network values must I copy exactly?

In the Network tab, copy the following without modifying them:

• the additional IP address;
• the prefix/netmask;
• the gateway;
• the dedicated virtual MAC.

You can use the label to note which VM is concerned, for example web-prod-01. This greatly reduces errors during maintenance.

How do I assign the virtual MAC to my Proxmox VM?

On the VM’s network adapter, with the machine shut down, by pasting the exact MAC supplied with the IP.

1. Shut down the VM cleanly.
2. In Proxmox, open VM > Hardware > Network Device.
3. Select the configured public bridge, usually vmbr0.
4. Use the VirtIO model if the system has the driver.
5. In MAC address, enter exactly the MAC displayed in the customer area.
6. Confirm, then restart the VM.

If you are creating a new VM, enter this MAC directly at the Network step of the wizard.

How do I configure the additional IP on Linux?

The tool depends on the distribution: Netplan on many Ubuntu versions, NetworkManager on other systems, or /etc/network/interfaces on some Debian installations. Always use the values from your customer area.

Netplan example to adapt:

network:
  version: 2
  ethernets:
    ens18:
      addresses:
        - ADDITIONAL_IP/PREFIX
      routes:
        - to: default
          via: GATEWAY
          on-link: true
      nameservers:
        addresses: [1.1.1.1, 9.9.9.9]

Check the actual name of the interface with ip link, then apply the configuration carefully:

sudo netplan try
sudo netplan apply
ip address
ip route

netplan try rolls back automatically if the new configuration cuts off your session.

How do I configure the additional IP on Windows?

In the IPv4 properties of the network adapter, using the IP, mask, gateway and DNS servers provided.

1. Open the network adapter properties.
2. Edit Internet Protocol Version 4 (TCP/IPv4).
3. Enter the IP, mask/prefix and gateway provided.
4. Add reliable DNS servers.
5. In Device Manager, check that the VirtIO driver is installed.

The MAC is configured in Proxmox, not in the Windows IPv4 window.

What should I do if the additional IP does not respond?

Work through the chain in order: address, default route, gateway, public IP, then domain name.

From the VM’s Proxmox console:

1. check the address and the default route;
2. test the gateway;
3. test a public IP, then a domain name;
4. check the VM’s firewall and the Proxmox firewall;
5. compare the MAC in Proxmox with the one in the customer area, character by character.

If the public IP responds but domain names do not, the problem usually lies with DNS. If nothing responds, check the bridge, gateway, prefix and IP/MAC pair first. Do not change the Proxmox node’s network blindly: use its console and, if necessary, open a ticket with the test results.