How to Configure a Private Network on CentOS

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.

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.

CentOS 8

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

2. Edit /etc/sysconfig/network-scripts/ifcfg-ens7

   # nano /etc/sysconfig/network-scripts/ifcfg-ens7
   

3. Change 10.10.10.3 to the selected private IP address and replace the contents of ifcfg-ens7 with:

   TYPE="Ethernet" 
   DEVICE="ens7" 
   ONBOOT="yes" 
   BOOTPROTO="none" 
   IPADDR=10.10.10.3
   PREFIX=16
   MTU=1450
   

4. Restart the connection, or reboot.

   # nmcli con load /etc/sysconfig/network-scripts/ifcfg-ens7
   # nmcli con up 'System ens7'
   

CentOS 7 and CentOS 6

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

2. Edit /etc/sysconfig/network-scripts/ifcfg-eth1

   # nano /etc/sysconfig/network-scripts/ifcfg-eth1
   

3. Change 10.10.10.3 to the selected private IP address and replace the contents of ifcfg-eth1 with:

   DEVICE=eth1
   ONBOOT=yes
   NM_CONTROLLED=no
   BOOTPROTO=static
   IPADDR=10.10.10.3
   NETMASK=255.255.0.0
   IPV6INIT=no
   MTU=1450
   

4. Start the interface or reboot.

   # ifup eth1
   

Manage Private Networks via API

The Vultr API offers several endpoints to manage private networks.