IPv6 Configuration for 3x-ui in Docker with Bridge Network

Introduction

When I started using 3x-ui in Docker, I encountered an issue with configuring IPv6 in a bridge network. By default, Docker doesn’t support IPv6 in bridge networks, although it works fine in host mode. To overcome this limitation and enable IPv6 capabilities in bridge networks, I created this guide.

Setup Steps

1. Enabling IPv6 Support in Docker

First, you need to enable IPv6 support in Docker. To do this, edit the Docker configuration. Open or create the /etc/docker/daemon.json file and add the following parameters:

{
  "ipv6": true,
  "fixed-cidr-v6": "2001:db8:1::/64"
}

This block enables IPv6 and sets a fixed subnet for containers. You can specify a different IPv6 address range instead of 2001:db8:1::/64 if you have other requirements.

2. Restart Docker

To apply the changes, restart the Docker service:

sudo systemctl restart docker

3. Creating a Bridge Network with IPv6 Support

The next step is to create a new network with IPv6 support. I like to name networks clearly to indicate their purpose. For example:

docker network create --ipv6 --subnet "2001:db8:1::/64" my-ipv6-network

Replace 2001:db8:1::/64 with your range if you’re using a different one. This will integrate your containers into your network infrastructure.

4. Running the Container with the New Network

Now you can launch the 3x-ui container, connecting it to the IPv6-enabled bridge network:

docker run --network my-ipv6-network -d your-container-image

Your container will automatically be set up to receive an IPv6 address and handle traffic through IPv6.

Example Docker Compose File for IPv6 and IPv4

Below is an example docker-compose.yml file that enables both IPv6 and IPv4 for the 3x-ui container. Instead of using network_mode: host, we create a custom network supporting both protocols:

version: "3.9"
services:
  3x-ui:
    image: ghcr.io/mhsanaei/3x-ui:latest
    container_name: 3x-ui
    hostname: yourhostname
    volumes:
      - $PWD/db/:/etc/x-ui/
      - $PWD/cert/:/root/cert/
    environment:
      XRAY_VMESS_AEAD_FORCED: "false"
    tty: true
    networks:
      - my-ipv6-network
    restart: unless-stopped

networks:
  my-ipv6-network:
    driver: bridge
    enable_ipv6: true
    ipam:
      driver: default
      config:
        - subnet: "2001:db8:1::/64"  # IPv6 subnet
        - subnet: "192.168.1.0/24"   # IPv4 subnet

Explanation

• This file creates a 3x-ui container that will use a network supporting both IPv4 and IPv6.
• Two subnets are defined: 2001:db8:1::/64 for IPv6 and 192.168.1.0/24 for IPv4.
• The container will automatically obtain both IPv4 and IPv6 addresses.

Conclusion

Now, your 3x-ui container in Docker operates with both IPv6 and IPv4 support in a bridge network. Configuring IPv6 and adding dual-protocol support through Docker Compose makes the infrastructure more flexible and ready for future demands. If you have questions or run into issues, consult Docker documentation or leave a comment. Setting up a dual-protocol network is a step towards a more universal infrastructure.