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How to Configure a Private Network on CentOS

Last Updated: Tue, Nov 17, 2020
CentOS FAQ Networking

Introduction

When deploying a Vultr cloud server with a private network, you need to manually configure the private adapter. The examples shown in this guide are IPv4, but Vultr supports both IPv4 and IPv6. Vultr also supports multiple VLANs over a single private network interface with 802.1q tags. You'll find your server's information on the information page under Settings > IPv4. In the example below, the public network address is 192.0.2.123, and the private network address is 10.10.10.3. You'll find configuration samples for your server by clicking "View our networking configuration tips and examples."

NetworkConfig


Private Networking Notes

  • When you enable private networking, you may use any RFC1918 private address as long as there are no conflicts with your other instances. Valid addresses include:
    • 10.0.0.0/8
    • 172.16.0.0/12
    • 192.168.0.0/16
  • Private IP addresses in the customer portal are suggestions. You are not required to use the suggested private IP addresses.
  • Private networks can not communicate between locations, regardless of IP addressing. For example, server instances in Miami can not see private networks in Dallas.
  • Private networks do not have DHCP, and you must manually manage your IP address space or install a DHCP server on your private network.
  • For optimal performance, set the private network adapter MTU to 1450 when configuring the NIC at the OS level.
  • We also have guides to configure multiple private networks.

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.

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