What happens when a docker container cannot access the external network?

In the process of using Docker containers, some users will encounter some problems. One of the more common problems is that Docker containers cannot access the external network. This problem mainly involves network settings and Docker configuration. Let’s analyze them one by one below.

1. Network settings

First, we need to ensure that the network settings on the host are normal. In a Linux system, you can use the following command to check whether the network settings of the host are normal:

ping www.baidu.com

If no error message appears, the network settings are normal. If there is an error message, you can troubleshoot through the following steps:

1. Check whether the network connection is smooth, for example, download a web page through the wget command to see if it can be downloaded normally.
2. Check whether the DNS configuration is correct. You can use the following command to view the DNS configuration of the host:

cat /etc/resolv.conf

If the DNS configuration is correct, you should be able to see the correct DNS server address.

3. Check whether the firewall blocks network access to the container. You can use the following command to view the firewall configuration:

iptables -L

If the firewall settings are incorrect, you can solve it by modifying the iptables rules question.

2. Docker configuration

When the network settings are normal, we need to check whether the Docker configuration is correct. The following are some common Docker configuration issues:

1. The network mode of the Docker container is incorrect

If the network mode of the Docker container is "bridge", the container cannot be accessed directly The external network needs to be accessed through the host's network connection. If the container's network mode is "host", the container can directly access the external network.

2. The IP address configuration of the Docker container is incorrect

Each Docker container has an IP address. If the IP address is incorrectly configured, the container will not be able to access the external network. You can use the following command to check the IP address of the container:

docker inspect <container_name>

If the IP address configuration is incorrect, you can use the following command to modify the IP address of the container:

docker network disconnect bridge <container_name>
docker network connect bridge --ip <new_ip_address> <container_name>

3. The network connection of the Docker container is not correct Stable

If the network connection of the Docker container is unstable, you can restart the Docker service through the following command to solve the problem:

systemctl restart docker

Summary

In summary, in When encountering the problem that the Docker container cannot access the external network, we need to check the network settings of the host and the configuration of Docker, including network mode, IP address configuration, and network connection stability. Through the above methods, we can solve the problem of most Docker containers accessing the external network.

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