Explore networking features on Docker Desktop
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:
$ 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:
$ 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:
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:
Bind mount the SSH agent socket by adding the following parameter to your
docker run
command:$--mount type=bind,src=/run/host-services/ssh-auth.sock,target=/run/host-services/ssh-auth.sock
Add the
SSH_AUTH_SOCK
environment variable in your container:$ -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:
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 Settings. 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.
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:
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
.Now, run a container, install
curl
, and try to connect to the host using the following commands:$ 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.
We recommend you 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:
$ 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
:
$ 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.
$ docker run -d -P --name webserver nginx
See the
run command for more details on
publish options used with docker run
.