How to Configure a Private Network on Debian

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Introduction

Vultr provides many flexible networking options for your cloud servers. In addition to the public network attached to every Vultr instance, you can configure up to five private networks per location. Private networks allow instances within a location to communicate without exposing the traffic to the public internet.

Note: Your network adapter names may not match the examples. See our article How to Find the Network Adapter Names for a Vultr Cloud Server.

Please see the guide How to Configure a Private Network at Vultr for general information about Vultr's private network feature.

Private networks do not have DHCP. When deploying a Vultr cloud server with private networking, you must manually configure the private adapters or supply your own DHCP server. We provide network configuration examples for many popular operating systems, pre-configured for your instance's IP addresses. You can find these by navigating to the settings screen (1) for your server, then selecting IPv4 (2). Follow the networking configuration link (3) to view the configuration examples.

The configurations in the customer portal are your best source of specific information. Please see below for step-by-step instructions with generic examples.

Debian 7, Debian 8

Verify that private networking is enabled for your cloud server. Your private network device is eth1. Your public network device is eth0.

Add the following text to the /etc/network/interfaces file. Replace 10.10.10.3 with your IP address.

auto eth1
iface eth1 inet static
    address 10.10.10.3
    netmask 255.255.0.0
    mtu 1450

Start the interface or reboot.

# ifup eth1

Debian 9, Debian 10

Verify that private networking is enabled for your cloud server. Your private network device is ens7. Your public network device is ens3.

Add the following text to the /etc/network/interfaces file. Replace 10.10.10.3 with your IP address.

auto ens7
iface ens7 inet static
    address 10.10.10.3
    netmask 255.255.0.0
    mtu 1450

Start the interface or reboot.

# ifup ens7

Optional: Use systemd-networkd

If you prefer to use systemd-networkd configuration instead of the default Debian networking configuration, follow these steps.

1. Move the existing interfaces file to disable it.

   # mv /etc/network/interfaces /etc/network/interfaces.save
   

2. Edit the public.network configuration.

   # nano /etc/systemd/network/public.network
   

   Add the following text.

   Use ens3 for Name on Debian 9 and 10.
   Use eth0 for Name on Debian 7 and 8.

   [Match]
   Name=ens3
   
   [Network]
   DHCP=yes
   

3. Save and exit the file.

4. Edit the private.network configuration.

   # nano /etc/systemd/network/private.network
   

   Add the following text.

   Replace 10.10.10.3 with your IP address.
   Use ens7 for Name on Debian 9 and 10.
   Use eth1 for Name on Debian 7 and 8.

   [Match]
   Name=ens7
   
   [Link]
   MTUBytes=1450
   
   [Network]
   Address=10.10.10.3/20
   

5. Save and exit the file.

6. Enable the new network services.

   # systemctl enable systemd-networkd
   # systemctl enable systemd-resolved
   

7. Start the new network services.

   # systemctl start systemd-networkd
   # systemctl start systemd-resolved
   

8. Disable the old network configuration.

   # systemctl disable networking
   

If the network fails to load, use the Vultr Web Console to make corrections. In rare cases, a reboot may be required.

Manage Private Networks via API

The Vultr API offers several endpoints to manage private networks.