Managing User-Defined Bridge Networks in Docker

can be used to modify the default address for published ports. Despite the option's name, it is possible to specify an IPv6 address. When the default binding address is an address assigned to a specific interface, the container's port will only be accessible via that address. Setting the default binding address to `::` means published ports will only be available on the host's IPv6 addresses. However, setting it to `0.0.0.0` means it will be available on the host's IPv4 and IPv6 addresses. To restrict a published port to IPv4 only, the address must be included in the container's publishing options. For example, `-p 0.0.0.0:8080:80`. ## Manage a user-defined bridge Use the `docker network create` command to create a user-defined bridge network. ```console $ docker network create my-net ``` You can specify the subnet, the IP address range, the gateway, and other options. See the [docker network create](/reference/cli/docker/network/create.md#specify-advanced-options) reference or the output of `docker network create --help` for details. Use the `docker network rm` command to remove a user-defined bridge network. If containers are currently connected to the network, [disconnect them](#disconnect-a-container-from-a-user-defined-bridge) first. ```console $ docker network rm my-net ``` > **What's really happening?** > > When you create or remove a user-defined bridge or connect or disconnect a > container from a user-defined bridge, Docker uses tools specific to the > operating system to manage the underlying network infrastructure (such as adding > or removing bridge devices or configuring `iptables` rules on Linux). These > details should be considered implementation details. Let Docker manage your > user-defined networks for you. ## Connect a container to a user-defined bridge When you create a new container, you can specify one or more `--network` flags. This example connects an Nginx container to the `my-net` network. It also publishes port 80 in the container to port 8080 on the Docker host, so external clients can access that port. Any other container connected to the `my-net` network has access to all ports on the `my-nginx` container, and vice versa. ```console $ docker create --name my-nginx \ --network my-net \ --publish 8080:80 \ nginx:latest ``` To connect a **running** container to an existing user-defined bridge, use the `docker network connect` command. The following command connects an already-running `my-nginx` container to an already-existing `my-net` network: ```console $ docker network connect my-net my-nginx ``` ## Disconnect a container from a user-defined bridge To disconnect a running container from a user-defined bridge, use the `docker network disconnect` command. The following command disconnects the `my-nginx` container from the `my-net` network. ```console $ docker network disconnect my-net my-nginx ``` ## Use IPv6 in a user-defined bridge network When you create your network, you can specify the `--ipv6` flag to enable IPv6. ```console $ docker network create --ipv6 --subnet 2001:db8:1234::/64 my-net ``` If you do not provide a `--subnet` option, a Unique Local Address (ULA) prefix will be chosen automatically. ## IPv6-only bridge networks To skip IPv4 address configuration on the bridge and in its containers, create the network with option `--ipv4=false`, and enable IPv6 using `--ipv6`. ```console $ docker network create --ipv6 --ipv4=false v6net ``` IPv4 address configuration cannot be disabled in the default bridge network. ## Use the default bridge network The default `bridge` network is considered a legacy detail of Docker and is not recommended for production use. Configuring it is a manual operation, and it has [technical shortcomings](#differences-between-user-defined-bridges-and-the-default-bridge).

This section explains how to manage user-defined bridge networks in Docker. It covers modifying the default address for published ports using IPv6 and IPv4, and creating, removing, connecting, and disconnecting containers from these networks using Docker commands. It also details how to enable and configure IPv6, create IPv6-only networks, and notes that the default bridge network is not recommended for production use due to technical limitations and manual configuration requirements.