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Configuring IPv6 on dedicated servers

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Learn how to configure IPv6 addresses on your server using various examples.

Internet Protocol version 6 (IPv6) is the latest version of the Internet Protocol (IP). It is designed to address the long-anticipated address exhaustion of its predecessor, IPv4, by using 128-bit addresses instead of 32-bit addresses. Most OVHcloud dedicated servers are delivered with a /64 IPv6 block, with the exception of High Grade and Scale servers, which are delivered with a /56 IPv6 block. This represents over 18 quintillion IP addresses that you can use at your convenience.

Info

This article is about primary IP configuration. For servers that support vRack connectivity, you can also configure Additional IP addresses in a vRack rather than on the public interface of your server. You can find the matching instructions in these guides:

Warning

NOTE: OVHcloud provides services for which you are responsible for their configuration and management. You are therefore responsible for their proper functioning.

This tutorial is designed to help you as much as possible with common tasks. If you are having difficulty performing these actions, please contact a specialized service provider. OVHcloud cannot provide you with technical support in this regard.

 

Requirements

  • A dedicated server in your OVHcloud account
  • All your IPv6 information (prefix, gateway, etc.)
  • Basic knowledge of SSH and networking
Warning

NOTE: Kimsufi servers are only provided with a single IPV6 block (/128). IPv6 will be configured automatically when installing the OS.

 

Instructions

The following sections contain configurations for the distributions we currently offer and the most commonly used distributions/operating systems. The first step is always to log in to your server via SSH or a GUI login session (RDP for a Windows server).

On dedicated servers, the first IPv6 is declared as 2607:5300:xxxx:xxxx::. For example, if we've assigned your server the IPv6 range: 2607:5300:abcd:efgh::/64, your server's first IPv6 is: 2607:5300:abcd:efgh::.

By default, the first IPv6 is configured on most of the recent Linux distributions we offer for installation, so the gateway is already included in the configuration file. In most cases, you won't need to add it again manually.

Please take note of the following terminology that will be used in code examples and instructions of the guide sections below:

TermDescriptionExample
YOUR_IPV6An IPv6 address from the IPv6 block assigned to your server2607:5300:xxxx:xxxx::1
IPv6_PREFIXThe prefix (or netmask) of your IPv6 block, usually 642607:5300:xxxx:xxxx::/64
IPv6_GATEWAYThe gateway of your IPv6 block2607:5300:xxxx:ff:ff:ff:ff:ff or fe80::1

In our examples, we'll use the nano text editor. Feel free to use the text editor of your choice.

 

Default Gateway

The first step is to identify the IPv6 block and gateway assigned to your server. There are two ways of doing this:

Via the OVHcloud Control Panel
Via the OVHcloud API

Via the OVHcloud Control Panel

Log in to the OVHcloud Control Panel, go to the Bare Metal Cloud section and select your server from Dedicated servers.

The IPv6 block and gateway assigned to your server will appear in the Network panel of the General Information tab. Once you have copied them, continue with applying the IPv6 configuration.

Dedicated panel - Network ipv6 - step 2

Warning

NOTE: Before modifying a configuration file, always create a backup of the original.

Info

With some operating systems, the addition of static IPv6 routes in the original configuration file is necessary and is done by default. If that is the case, simply add your configuration for IPv6 as instructed in the guide, do not modify any lines in the original file.

 

Tip

Select the tab corresponding to the operating system you are using.

Debian and derivatives(not Debian 12)
Fedora 38 and later
Debian 12, Ubuntu 20.04 and later
CentOS 7, AlmaLinux 8 & 9, Rocky Linux 8 & 9
Windows Server 2016 and later

Debian and Debian-based operating systems (excluding Debian 12)

The configuration example below is based on Debian 11 (Bullseye).

Warning

Before following the steps below, we strongly suggest that you disable IPv6 autoconf and router advertising to prevent known issues. You can do so by adding the following lines to your sysctl.conf file, which is located in /etc/sysctl.conf:

net.ipv6.conf.all.autoconf=0

net.ipv6.conf.all.accept_ra=0

Once this has been done, you can apply those rules by executing the following command: sudo sysctl -p.

Step 1: Connect to your server via SSH
ssh user@serverIP
Step 2: Create a backup

Your server's network configuration file is located in /etc/network/interfaces.d. In our example, it is called 50-cloud-init. Before proceeding, create a backup of your file using the following command:

sudo cp /etc/network/interfaces.d/50-cloud-init /etc/network/interfaces.d/50-cloud-init.bak
Step 3: Amend the network configuration file

Do not modify the existing lines in the configuration file. Add the lines for your IPv6 configuration, replacing YOUR_IPv6 and IPv6_PREFIX with your own values. In this example, the network interface is called eth0. The interface on your server may differ.

auto eth0
iface eth0 inet dhcp
    accept_ra 0

iface eth0 inet6 static
    address YOUR_IPv6
    netmask IPv6_PREFIX

# control-alias eth0
iface eth0 inet6 static
    address 2607:5300:xxxx:xxxx::/xx
    dns-nameservers 2001:41d0:3:163::1
    gateway 2607:5300:xxxx:xxff:ff:ff:ff:ff

Debian 10

iface eth0 inet6 static 
    address YOUR_IPv6 
    netmask 64

post-up /sbin/ip -f inet6 route add IPv6_GATEWAY dev eth0 
post-up /sbin/ip -f inet6 route add default via IPv6_GATEWAY 
pre-down /sbin/ip -f inet6 route del IPv6_GATEWAY dev eth0
pre-down /sbin/ip -f inet6 route del default via IPv6_GATEWAY

Additional IPv6 addresses can be added with the following lines in the configuration file: up ip -6 addr add ADDITIONAL_IPV6_1/IPv6_PREFIX dev eth0, up ip -6 addr add ADDITIONAL_IPV6_2/IPv6_PREFIX dev eth0 etc...

To ensure that the IPv6 is enabled or disabled whenever the eth0 interface is enabled or disabled, you need to add the following line to the configuration:

down ip -6 addr del ADDITIONAL_IPV6_1/IPv6_PREFIX dev eth0
down ip -6 addr del ADDITIONAL_IPV6_2/IPv6_PREFIX dev eth0

Configuration example:

auto eth0
iface eth0 inet dhcp
    accept_ra 0

iface eth0 inet6 static
    address 2607:5300:adce:f2cd::1
    netmask 64

# control-alias eth0
iface eth0 inet6 static
    address 2607:5300:xxxx:xxxx::/xx
    dns-nameservers 2001:41d0:3:163::1
    gateway 2607:5300:xxxx:xxff:ff:ff:ff:ff

Adding additional IPv6 addresses:

auto eth0
iface eth0 inet dhcp
    accept_ra 0

iface eth0 inet6 static
    address 2607:5300:adce:f2cd::1
    netmask 64
    up ip -6 addr add 2607:5300:adce:f2cd::2/64 dev eth0
    up ip -6 addr add 2607:5300:adce:f2cd::3/64 dev eth0
    down ip -6 addr del 2607:5300:adce:f2cd::2/64 dev eth0
    down ip -6 addr del 2607:5300:adce:f2cd::3/64 dev eth0

# control-alias eth0
iface eth0 inet6 static
    address 2607:5300:xxxx:xxxx::/xx
    dns-nameservers 2001:41d0:3:163::1
    gateway 2607:5300:xxxx:xxff:ff:ff:ff:ff
Step 4: Save the file and apply the changes

Save your changes to the file and then restart the network or reboot your server to apply the changes.

sudo /etc/init.d/networking restart
Step 5: Test the IPv6 connectivity

You can test the IPv6 connectivity by running the commands shown below:

ping6 -c 4 2001:4860:4860::8888

PING 2001:4860:4860::8888(2001:4860:4860::8888) 56 data bytes
64 bytes from 2001:4860:4860::8888: icmp_seq=1 ttl=57 time=4.07 ms
64 bytes from 2001:4860:4860::8888: icmp_seq=2 ttl=57 time=4.08 ms
64 bytes from 2001:4860:4860::8888: icmp_seq=3 ttl=57 time=4.08 ms
64 bytes from 2001:4860:4860::8888: icmp_seq=4 ttl=57 time=4.07 ms

--- 2001:4860:4860::8888 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3003ms
rtt min/avg/max/mdev = 4.075/4.079/4.083/0.045 ms

If you are not able to ping this IPv6 address, check your configuration and try again. Also ensure that the machine you are testing from is connected with IPv6. If it still does not work, please test your configuration in Rescue mode.

 

Diagnostic

Have you configured your IPv6, but found that nothing works?

There is a simple operation to determine whether the error is in your configuration, or on the OVHcloud network.

First, put your server into rescue mode.

Next, use the template commands below to configure your IPv6 non-persistently, replacing ‘YOUR_IPV6’, ‘IPV6_PREFIX’ and 'IPV6_GATEWAY' with your own details:

ip addr add YOUR_IPV6/IPV6_PREFIX dev eth0
ip -6 route add IPV6_GATEWAY dev eth0
ip -6 route add default via IPV6_GATEWAY dev eth0

Test your network again via a ping6, for example:

ping6 ipv6.google.com

If your server responds, there is likely an error in one of the steps taken for your initial configuration.

In any case, feel free to contact our support team and ask to review your configurations. You will need to provide:

  • The operating system name and version you are using on your server.
  • The name and directory of the network configuration file.
  • The content of that file.

 

Go further

Browse all the Dedicated Servers guides.

Browse the rest of the OVHcloud US documentation for guides on our other products and services.

Learn more about Dedicated Servers on the OVHcloud US website.