Network

Docker automatically creates three networks after installation:

bridge
host
none

Two additional network types are also available:

overlay — Connects multiple Docker Daemon hosts (Docker running on different machines).
macvlan — Assigns a custom MAC address to a container for direct communication.

Network Types

None
Host
Bridge

No network is attached to the container. The container has no access to any external network or other containers and runs in full isolation with no IP configuration.

docker run --network=none ubuntu

The host network driver removes network isolation between the Docker host and Docker containers, using the host’s networking directly. The container does not get its own IP address.

Container port 80 = Host port 80. No -p flag needed.

If you run a container that binds to port 80, the application will be available on port 80 of the host’s IP directly.

docker run --network=host apiapp

The default network attached to all containers. Docker creates a private internal network called bridge on the host (docker0, typically 172.17.0.1). Containers receive an internal IP address in the 172.17.x.x range.

Use ip addr to inspect the docker0 bridge interface.

Key properties:

Containers on the same bridge network can communicate with each other while remaining isolated from other containers.
Containers can find each other by name instead of IP.
Environment variables are shared between linked containers.

docker run ubuntu  # uses bridge network by default

User-Defined Bridge Network

You can create your own internal network with a custom subnet:

docker network create --driver bridge --subnet 192.168.10.0/24 mynewinternalnetwork

This creates a network with an IP range of 192.168.10.1–192.168.10.254.

Network Operations

List networks

docker network ls

Inspect a network

docker network inspect <network-name>

Remove a network

docker network rm <network-name>
docker network prune  # remove all unused networks

Connect / Disconnect a container

docker network connect <network-name> <container>
docker network disconnect <network-name> <container>

Container Communication

Container to host communication

To communicate with services on the host machine from inside a container, replace localhost or the host IP with host.docker.internal. This domain resolves to the host machine’s IP as seen from inside the container. Example: Change mongodb://localhost:27017/user to mongodb://host.docker.internal:27017/user.

Container to container communication

Method 1 (Not Recommended)
Method 2 (Recommended)

Use docker inspect <container> to find the container’s IP address, then hardcode it:

mongodb://172.17.0.3:27017/user

This is fragile because container IPs can change.

Use the container name instead of an IP address. Docker resolves container names to their allocated IPs via docker0.

mongodb://mymongodb:27017/user

Containers must be on the same network for name-based resolution to work.

Overview

Docker

Git

Kubernetes

Kubernetes Scheduling

Kubernetes Observability

Kubernetes Cluster Maintenance

Kubernetes Security

Linux

SSH

Ansible

Taskfile

Python OOP

Data Structures & Algorithms

12-Factor App

Network Types

User-Defined Bridge Network

Network Operations

List networks

Inspect a network

Remove a network

Connect / Disconnect a container

Container Communication

Container to host communication

Container to container communication

Build docs developers (and LLMs) love

Overview

Docker

Git

Kubernetes

Kubernetes Scheduling

Kubernetes Observability

Kubernetes Cluster Maintenance

Kubernetes Security

Linux

SSH

Ansible

Taskfile

Python OOP

Data Structures & Algorithms

12-Factor App

​Network Types

​User-Defined Bridge Network

​Network Operations

​List networks

​Inspect a network

​Remove a network

​Connect / Disconnect a container

​Container Communication

​Container to host communication

​Container to container communication

Build docs developers (and LLMs) love

Network Types

User-Defined Bridge Network

Network Operations

List networks

Inspect a network

Remove a network

Connect / Disconnect a container

Container Communication

Container to host communication

Container to container communication