title: How to enable IPv6 in docker
---
pub_date: 2019-12-13
---
author: ungleich virtualisation team
---
twitter_handle: ungleich
---
_hidden: no
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_discoverable: yes
---
abstract:
The first step to enable docker containers with IPv6
---
body:

If you are like us and like to do fun things with IPv6 and if you also
like to run docker containers, then this article is for you.

## Enabling IPv6 in docker

Recent docker versions just need to have the **ipv6** flag and an IPv6
network specfied in the **daemon.json**. This might look as follows:

```
{
  "ipv6": true,
  "fixed-cidr-v6": "your-ipv6-network-here"
}
```

This configuration needs to be placed in **/etc/docker/daemon.json**.

## Selecting the right IPv6 network

In the IPv6 world we usually say, "just take a /64 for
everything". And while we will never create 18446744073709551616
containers on one host, we will just follow this dogma and use
a /64 for docker.

Why would we do this? One of the big advantages of IPv6 is that things
get simpler. Instead of using a tiny network like a /120 that is
suitable for 256 containers, we always choose a /64. This way we don't
have to use our brain power on choosing the network size or to
eventually later resize the network.

If you have a /48 assigned to your host (like when you use the
[IPv6VPN](https://IPv6VPN.ch)), you can basically use **any** of the
65'536 networks that are available. We like to remember names so we
usually take the **b00** network for containers (b00 as in the sound a
ghost makes when flying around).

So if your main /48 network was for instance 2a0a:e5c1:137::/48, we
would use *2a0a:e5c1:137:b00::/64* and the daemon.json configuration file
would look as follows:

```
{
  "ipv6": true,
  "fixed-cidr-v6": "2a0a:e5c1:137:b00::/64"
}
```

After adding this configuration, you will also need to restart the
docker daemon. After that, your containers should be using IPv6.

## IPv6++

If you want to learn more about IPv6 or how to secure your docker
containers, stay tuned for the next blog posts, which will explain on
how to secure access to your docker containers.

In the mean time, you can also join the IPv6 discussion on
[IPv6.Chat](https://IPv6.chat) or if you want to spawn your docker
containers on a VM, you can do so on
[IPv6OnlyHosting.com](https://IPv6OnlyHosting.com).