add a 'networking' for all platforms page

_data/toc.yaml

@@ -1186,8 +1186,6 @@ manuals:
           title: Install Docker Desktop for Mac
         - path: /desktop/mac/
           title: User manual
-        - path: /desktop/mac/networking/
-          title: Networking
         - path: /desktop/mac/space/
           title: Disk utilization
         - path: /desktop/mac/troubleshoot/
@@ -1200,8 +1198,6 @@ manuals:
           title: Install Docker Desktop for Windows
         - path: /desktop/windows/
           title: User manual
-        - path: /desktop/windows/networking/
-          title: Networking
         - path: /desktop/windows/troubleshoot/
           title: Logs and troubleshooting
         - path: /desktop/windows/wsl/
@@ -1222,8 +1218,6 @@ manuals:
               title: Install on Arch
         - path: /desktop/linux/
           title: User manual
-        - path: /desktop/linux/networking/
-          title: Networking
         - path: /desktop/linux/space/
           title: Disk utilization
         - path: /desktop/linux/troubleshoot/
@@ -1232,6 +1226,8 @@ manuals:
       title: Dashboard
     - path: /desktop/dev-environments/
       title: Dev Environments (Preview)
+    - path: /desktop/networking/
+      title: Explore networking features
     - path: /desktop/extensions/
       title: Extensions (Beta)
     - sectiontitle: Extensions SDK (Beta)

desktop/networking.md

@@ -0,0 +1,163 @@
+---
+description: Networking on Docker Desktop
+keywords: netowrking, docker desktop
+title: Explore networking features
+redirect_from:
+- /desktop/linux/networking/
+- /docker-for-mac/networking/
+- /mackit/networking/
+- /desktop/mac/networking/
+- /docker-for-win/networking/
+- /docker-for-windows/networking/
+- /desktop/windows/networking/
+---
+
+Docker Desktop provides several networking features to make it easier to
+use.
+
+## Features for all platforms
+
+### VPN Passthrough
+
+Docker Desktop networking can work when attached to a VPN. To do this,
+Docker Desktop intercepts traffic from the containers and injects it into
+the host as if it originated from the Docker application.
+
+### Port Mapping
+
+When you run a container with the `-p` argument, for example:
+
+```console
+$ docker run -p 80:80 -d nginx
+```
+
+Docker Desktop makes whatever is running on port 80 in the container (in
+this case, `nginx`) available on port 80 of `localhost`. In this example, the
+host and container ports are the same. If, for example, you already have something running on port 80 of
+your host machine, you can connect the container to a different port:
+
+```console
+$ docker run -p 8000:80 -d nginx
+```
+
+Now, connections to `localhost:8000` are sent to port 80 in the container. The
+syntax for `-p` is `HOST_PORT:CLIENT_PORT`.
+
+### HTTP/HTTPS Proxy Support
+
+See:
+- [Proxies on Linux](linux/index.md#proxies)
+- [Proxies on Mac](mac/index.md#proxies)
+- [Proxies on Windows](windows/index.md#proxies)
+
+## Features for Mac and Linux
+
+### SSH agent forwarding
+
+Docker Desktop on Mac and Linux allows you to use the host’s SSH agent inside a container. To do this:
+
+1. Bind mount the SSH agent socket by adding the following parameter to your `docker run` command:
+
+    `--mount type=bind,src=/run/host-services/ssh-auth.sock,target=/run/host-services/ssh-auth.sock`
+
+1. Add the `SSH_AUTH_SOCK` environment variable in your container:
+
+    `-e SSH_AUTH_SOCK="/run/host-services/ssh-auth.sock"`
+
+To enable the SSH agent in Docker Compose, add the following flags to your service:
+
+ ```yaml
+services:
+  web:
+    image: nginx:alpine
+    volumes:
+      - type: bind
+        source: /run/host-services/ssh-auth.sock
+        target: /run/host-services/ssh-auth.sock
+    environment:
+      - SSH_AUTH_SOCK=/run/host-services/ssh-auth.sock
+ ```
+
+## Known limitations for all platforms
+
+### Changing internal IP addresses
+
+The internal IP addresses used by Docker can be changed from the Settings, if you're a Windows user, or Preferences, if you use Mac or Linux. After changing IPs, it is necessary to reset the Kubernetes cluster and to leave any active Swarm.
+
+### There is no docker0 bridge on the host
+
+Because of the way networking is implemented in Docker Desktop, you cannot
+see a `docker0` interface on the host.  This interface is actually within the
+virtual machine.
+
+### I cannot ping my containers
+
+Docker Desktop can't route traffic to Linux containers.  However if you're a Windows user, you can
+ping the Windows containers.
+
+### Per-container IP addressing is not possible
+
+The docker bridge network is not reachable from the host.
+However if you are a Windows user, it works with Windows containers.
+
+## Use cases and workarounds for all platforms
+
+### I want to connect from a container to a service on the host
+
+The host has a changing IP address (or none if you have no network access). We recommend that you connect to the special DNS name
+`host.docker.internal` which resolves to the internal IP address used by the
+host. This is for development purpose and does not work in a production environment outside of Docker Desktop.
+
+You can also reach the gateway using `gateway.docker.internal`.
+
+If you have installed Python on your machine, use the following instructions as an example to connect from a container to a service on the host:
+
+1. Run the following command to start a simple HTTP server on port 8000.
+
+    `python -m http.server 8000`
+
+    If you have installed Python 2.x, run `python -m SimpleHTTPServer 8000`.
+
+2. Now, run a container, install `curl`, and try to connect to the host using the following commands:
+
+    ```console
+    $ docker run --rm -it alpine sh
+    # apk add curl
+    # curl http://host.docker.internal:8000
+    # exit
+    ```
+
+#### I want to connect to a container from the host
+
+Port forwarding works for `localhost`; `--publish`, `-p`, or `-P` all work.
+Ports exposed from Linux are forwarded to the host.
+
+Our current recommendation is to publish a port, or to connect from another
+container. This is what you need to do even on Linux if the container is on an
+overlay network, not a bridge network, as these are not routed.
+
+For example, to run an `nginx` webserver:
+
+```console
+$ docker run -d -p 80:80 --name webserver nginx
+```
+
+To clarify the syntax, the following two commands both publish container's port `80` to host's port `8000`:
+
+```console
+$ docker run --publish 8000:80 --name webserver nginx
+
+$ docker run -p 8000:80 --name webserver nginx
+```
+
+To publish all ports, use the `-P` flag. For example, the following command
+starts a container (in detached mode) and the `-P` flag publishes all exposed ports of the
+container to random ports on the host.
+
+```console
+$ docker run -d -P --name webserver nginx
+```
+
+See the [run command](../../engine/reference/commandline/run.md) for more details on
+publish options used with `docker run`.
+