How to Enable Additional IPv6 Addresses on your Droplet

By default, each Droplet with IPv6 enabled will be configured with a single IPv6 address. This address is used for any PTR records generated for domains pointing at the server.

A broader range of addresses is also available for your Droplet, visible in the Networking section of a Droplet’s configuration page under Configurable address range. The DigitalOcean backend is already set up to serve requests for these addresses. However, you will need to configure the network on the Droplet to use the additional addresses.

In your assigned IPv6 range, you have access to 16 addresses. The first address in the range will end with a 0. Each additional address increments the last digit hexadecimally from 0 - f.

See an example

You can add as many IPv6 addresses from a Droplet’s addressable range as you like. Multiple addresses allow flexibility in your configuration and allow you to use different addresses for specific purposes.

Enable New Addresses on Boot

To set up additional IPv6 addresses, you will add the new addresses to the file that configures your network at boot. The file you edit and the lines you add depend on which Linux distribution the Droplet is running.

On Ubuntu 18.04

Open the file /etc/netplan/50-cloud-init.yaml with root privileges. In the addresses: section, add each IPv6 address on its own line, as follows:

  
    
network:
    version: 2
    ethernets:
        eth0:
            addresses:
            - 203.0.113.213/20
            - your_primary_ipv6_address/64
            - your_additional_ipv6_address/64
            - 192.0.2.11/16
            gateway4: 206.189.208.1
            gateway6: ipv6_gateway
            match:
                macaddress: ce:2c:ex:am:pl:e6

  

To apply the change and test:

  1. Run sudo netplan apply --debug. When the command is successful, it won’t provide output.
  2. Run ping6 your_additional_ipv6_address. If you can reach the new address with ping6, it is correctly configured.

A reboot is not necessary, because the above netplan command implements the changes immediately.

On Debian or Ubuntu 16.04 or earlier

On Debian and Ubuntu 16.04, edit the file /etc/network/interfaces.d/50-cloud-init.cfg with root privileges. On Ubuntu 14.04 or earlier, edit /etc/network/interfaces.

Edit the file /etc/network/interfaces.d/50-cloud-init.cfg with root privileges. You will find a section in this file for each of the different networks that you have configured. These may be public IPv4, public IPv6, private IPv4, etc. The public IPv6 interface section begins with iface eth0 inet6 static, for example.

To add an additional IPv6 address that will be also be available publicly, you need to add an additional section that mirrors the specification you currently have. Underneath the public IPv6 interface, add an additional section that includes the new address you are adding and a netmask specification:

  
    
iface eth0 inet6 static
        address new_ipv6_address/64

  

You will add an additional iface eth0 inet6 static section for each new IPv6 address you wish to add to the Droplet.

On CentOS or Fedora

Edit the file /etc/sysconfig/network-scripts/ifcfg-eth0 with root privileges. The portion of this file that deals with IPv6 addresses includes lines like IPV6INIT=yes. To add additional IPv6 addresses, you need to add a parameter called IPV6ADDR_SECONDARIES. This will be set to a string which defines any other IPv6 addresses that we may want to add.

Add a new line that begins with IPV6ADDR_SECONDARIES= anywhere in the file, then list all of the IPv6 addresses you’re adding, separated by spaces. The line should look like this, with your IPv6 addresses:

  
    
IPV6ADDR_SECONDARIES="second_ipv6_address/64 third_ipv6_address/64 .../64"

  

When you’re done, save your changes and exit.

Regardless of which distribution you run (other than Ubuntu 18.04, as noted above), the addresses you added will automatically be configured on a reboot.

sudo shutdown -r now

If you want these additional addresses to be available prior to rebooting on the other distributions, you can also enable them immediately as below.

Enable New Addresses Immediately

Adding new IPv6 addresses to your Droplet’s interface will make the addresses available immediately.

To configure the Droplet’s networking interface, select the address you want to configure out of your address range and add it using ip -6 addr add, like this:

ip -6 addr add new_ipv6_address/64 dev eth0

The new address will immediately be available in your session. You can check by listing them:

ip -6 addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 first_ipv6_address/64 scope global 
       valid_lft forever preferred_lft forever
    inet6 second_ipv6_address/64 scope global 
       valid_lft forever preferred_lft forever

The new address will be available for the duration of your current session. If you want the IP address to persist across reboots, make sure to enable it in your networking configuration file as above.