> For the complete documentation index, see [llms.txt](https://42-guide.gitbook.io/42-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://42-guide.gitbook.io/42-guide/docker/networking.md).

# Networking

#### **What is Docker Networking?**

Docker networking allows multiple containers to communicate with each other or with the outside world (e.g., the internet). Think of it as a virtual network where containers can "talk" to one another.

***

#### **Types of Docker Networks**

Docker provides different network drivers depending on your needs:

**1️⃣ Bridge (Default Network)**

* Containers share a private network on the same Docker host.
* They can talk to each other via their **container name** or **IP address**.
* Used for most standalone containers.

**Example:**

```bash
docker network create mynetwork
docker run -d --name app --network mynetwork nginx
docker run -d --name db --network mynetwork mysql
```

* Both `app` and `db` can communicate on the `mynetwork`.

***

**2️⃣ Host**

* The container shares the **host’s network stack**.
* No isolation — the container uses the host’s IP address and ports.
* Faster, but not ideal for security.

**Example:**

```bash
docker run --network host nginx
```

Use this when performance is critical (e.g., running a web server without any network overhead).

***

**3️⃣ None**

* The container has **no network access** (fully isolated).
* Useful for running tasks that don’t require networking.

**Example:**

```bash
docker run --network none busybox
```

***

**4️⃣ Overlay**

* Connects containers **across multiple Docker hosts**.
* Used in Docker Swarm or Kubernetes for distributed applications.

**Example:**

```bash
docker network create -d overlay myoverlay
```

***

#### **How to Connect Containers?**

1. **Using a Custom Network**

   * Containers in the same custom network can use **container names** to talk to each other.

   Example:

   ```bash
   bashKopierenBearbeitendocker network create mynetwork
   docker run -d --name app --network mynetwork nginx
   docker run -d --name db --network mynetwork mysql
   ```

   * Inside the `app` container, you can use:

     ```bash
     ping db
     ```

     This works because both containers are on the same network.

***

#### **How to Check Network Details?**

1. **List all networks:**

   ```bash
   docker network ls
   ```
2. **Inspect a specific network:**

   ```bash
   docker network inspect mynetwork
   ```

   * This shows details like connected containers, IP addresses, and network configurations.

***

#### **Advanced Networking Concepts**

* **Subnets and IP Ranges**: You can specify a subnet for your network during creation.

  ```bash
  docker network create --subnet=192.168.1.0/24 mynetwork
  ```
* **Aliases**: Assign alternative names for containers within the network.

  ```bash
  docker network connect --alias db_alias mynetwork db
  ```

***

#### **When to Use Different Networks?**

* **Bridge**: Default for local containers on the same host.
* **Host**: For maximum performance or when you need direct access to the host's network.
* **None**: To isolate containers completely.
* **Overlay**: For multi-host applications (e.g., in a Docker Swarm or Kubernetes setup).

***

#### **In Summary**

Docker networking allows you to connect containers easily:

* Create a **custom network** to link containers.
* Use different network types depending on your use case (local, distributed, isolated).
* **Inspect networks** to see connections and troubleshoot issues.


---

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