What should I do if the docker container cannot access the external network?

Solution to Docker container being unable to access the external network

When the Docker container cannot access the external network, it may be due to the following reasons:

1. NAT Port Mapping is not configured

Docker containers cannot directly access the external network by default. NAT port mapping is required to map container ports to host ports. For example:

<code>docker run -p 8080:80 nginx</code>

The above command maps port 80 of the container to port 8080 on the host.

2. The network driver is not compatible

Docker uses the bridge network driver by default. If the host does not support bridge networking, you need to use other drivers, such as host or overlay. For example:

<code>docker run --net=host nginx</code>

3. Firewall Blocking

The firewall on the host may prevent the container from accessing the external network. The port that the container needs to be allowed to use. For example:

<code>sudo ufw allow 8080</code>

4. DNS resolution issues

The container may not be able to resolve external DNS names. The correct DNS server needs to be configured in the container. For example:

<code>docker run --dns 8.8.8.8 nginx</code>

5. Improper container network mode

The network mode of a Docker container determines how the container connects to the network. Using the wrong network mode may prevent the container from accessing the external network. For example:

<code>docker run --network=none nginx</code>

6. Host network problems

Host network problems may also cause the container to be unable to access the external network. Please check that the host network connection is normal and there are no firewalls or other network restrictions.

If none of the above steps resolve the issue, you can try the following:

• Check the container logs for more information
• Restart the Docker daemon
• Upgrade Docker version
• Contact the Docker community for help

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