search
HomeOperation and MaintenanceDockerWhat should I do if docker cannot ping the host?

Solutions to the problem that docker cannot ping the host: 1. Modify daemon.json; 2. Turn off the firewall; 3. Modify sysctl.conf; 4. Reset the network bridge.

What should I do if docker cannot ping the host?

The operating environment of this article: ubuntu16.04 system, Docker 20.10.11, Dell G3 computer.

What should I do if docker cannot ping the host?

Docker bridge mode cannot ping the host

Problem description:

 DockerThe network mode is divided into four types. Generally, when we do not set it, the default is bridgesingle bridge mode, the container uses an independent network Namespace and is connected to the docker0 virtual network card. Communicate with the host through the docker0 bridge and Iptables nat table configuration.
  At this time, test on the bastion machine and use busybox to test:

# 拉取镜像
docker pull busybox
# 运行容器
docker run -itd --name busy_bridge busybox

  Instruction docker network inspect bridge Check the network:
What should I do if docker cannot ping the host?

## The network configuration is successful. Go inside the container and check

ip. You can see that ip has been allocated, but ping fails when pinging the external network and cannot Connect to the external network:
What should I do if docker cannot ping the host?

 But when you conduct the same test locally or on Alibaba Cloud, you find that you can connect to the network. What is the problem?

Problem Analysis:

After finding information on the Internet, many people restart

docker, and then they can connect. Usually it is because a certain configuration is modified and then Restarting works, it has no effect here. Generally, there are several types of modifications. Try them one by one below:

  1. Modifydaemon.json
The container cannot access the host because the network segment allocated by the bridge conflicts with the host. You need to modify

daemon.json to specify the allocation. Use the command vim /etc/docker/daemon.jsonAdd after entering:

{"bip":"172.16.10.1/24"}
 Although you can access it by restarting

docker and creating a container, there is no conflict at all between the ip assigned by the original bastion host and the container. The method doesn’t work.

  1. Turn off the firewall
The container cannot access the host through the bridge, and therefore cannot access the external network. The firewall may be blocking access, so you can turn it off Firewall or open a certain port. Tested on the server, turned on the firewall, and found that the container was indeed unable to access the Baidu homepage and the host. After closing the firewall and restarting

docker, the container could be accessed normally.  However, the firewall on the bastion machine is originally turned off, so this method is useless.

  1. Modifysysctl.conf
  2. ##  
docker

The internal network of the host is normal, and the network with other hosts is normal. The connection fails. Other hosts cannot connect to the port mapped on the docker host, and docker cannot connect to external hosts internally. Use the docker info command to check the information and find the following error: <pre class="brush:php;toolbar:false">WARNING: IPv4 forwarding is disabled WARNING: bridge-nf-call-iptables is disabled WARNING: bridge-nf-call-ip6tables is disabled</pre>  Use the command

vim /etc/sysctl.conf

Edit the configuration file and add the following code to the file: <pre class="brush:php;toolbar:false">net.bridge.bridge-nf-call-ip6tables=1 net.bridge.bridge-nf-call-iptables=1 net.bridge.bridge-nf-call-arptables=1 net.ipv4.ip_forward=1</pre>  Then use the command

systemctl restart network

Restart the network and check docker info again, the warning disappears. But it's still useless. The container on the bastion machine still cannot access the host machine through the bridge and cannot access the external network.

    Reset the bridge
  1. After using the command
yum install bridge-utils

to install the tool, use brctl show Check the network bridge and you can find:
Use the What should I do if docker cannot ping the host?docker network create [bridge name]
command to create a new network bridge and find the generated bridge id is still 8000.0000000000, create a container on the new bridge, and check again and there is no change, indicating that it is probably a problem with the bridge.  Test again. At this time, the bridge ip
is 172.17.0.1 and the container ip is 172.0.0.2. The host function is found. ping The network bridge is connected, but the container cannot be connected. The container cannot connect to the network bridge and cannot connect to the host, let alone the external network, so there must be a problem with the network bridge. <h3 id="问题解决">问题解决</h3> <p>  这里<code>docker network生成新的网桥不行,说明dockernetwork存在问题,我们利用刚才下载的bridge-utils来创建网桥。
  首先暂停docker服务,利用指令:

service docker stop

  添加网桥:

brctl addbr br0

  添加ip字段:

ip addr add 172.16.0.1/24 dev br0

  启用网桥br0

ip link set dev br0 up

  查看网络br0
What should I do if docker cannot ping the host?

  修改docker默认网桥:

vim /etc/docker/daemon.json

  添加字段:

"bridge":"br0"

  重启docker

service docker start

  此时查看网桥:
What should I do if docker cannot ping the host?

  在没有挂载容器前,依旧是8000.000000000000。运行测试容器:

docker run -itd --name busy_test busybox

  查看What should I do if docker cannot ping the host?:
What should I do if docker cannot ping the host?

  此时容器挂载在网桥上了,再次查看网桥id
What should I do if docker cannot ping the host?

  说明已经其作用,进入测试容器内部,What should I do if docker cannot ping the host?:
What should I do if docker cannot ping the host?

  成功!
  补充:这里使用docker network新建网桥,没有用,发现新建网桥挂载容器后,其bridge id依旧不变,没有起作用,说明堡垒机上的docker network可能存在问题。

问题补充:

  上面的问题是创建自定义网桥,然后在自定义网桥上连接容器ab,结果宿主机无法pingab,且进入容器内部后,两个容器无法ping通自定义网络,但能彼此相通。
  查了很多资料,发现了这篇文章。博主说问题原因是系统内核的网桥模块bridge.ko加载失败导致,解决问题的方案是升级内核或升级系统。
  升级centos内核参考这篇。
  升级完成后,重装Docker,自定义网桥和容器,成功!不再有网络问题。

推荐学习:《docker视频教程

The above is the detailed content of What should I do if docker cannot ping the host?. For more information, please follow other related articles on the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Docker vs. Kubernetes: Deciding Which to UseDocker vs. Kubernetes: Deciding Which to UseApr 29, 2025 am 12:05 AM

The difference between Docker and Kubernetes is that Docker is a containerized platform suitable for small projects and development environments; Kubernetes is a container orchestration system suitable for large projects and production environments. 1.Docker simplifies application deployment and is suitable for small projects with limited resources. 2. Kubernetes provides automation and scalability capabilities, suitable for large projects that require efficient management.

Docker and Kubernetes: Building Scalable ApplicationsDocker and Kubernetes: Building Scalable ApplicationsApr 28, 2025 am 12:18 AM

Use Docker and Kubernetes to build scalable applications. 1) Create container images using Dockerfile, 2) Deployment and Service of Kubernetes through kubectl command, 3) Use HorizontalPodAutoscaler to achieve automatic scaling, thereby building an efficient and scalable application architecture.

Kubernetes and Docker: A Comparative AnalysisKubernetes and Docker: A Comparative AnalysisApr 27, 2025 am 12:05 AM

The main difference between Docker and Kubernetes is that Docker is used for containerization, while Kubernetes is used for container orchestration. 1.Docker provides a consistent environment to develop, test and deploy applications, and implement isolation and resource limitation through containers. 2. Kubernetes manages containerized applications, provides automated deployment, expansion and management functions, and supports load balancing and automatic scaling. The combination of the two can improve application deployment and management efficiency.

Running Docker on Linux: Installation and ConfigurationRunning Docker on Linux: Installation and ConfigurationApr 26, 2025 am 12:12 AM

Installing and configuring Docker on Linux requires ensuring that the system is 64-bit and kernel version 3.10 and above, use the command "sudoapt-getupdate" and install it with the command "sudoapt-getupdate" and verify it with "sudoapt-getupdate" and. Docker uses the namespace and control groups of the Linux kernel to achieve container isolation and resource limitation. The image is a read-only template, and the container can be modified. Examples of usage include running an Nginx server and creating images with custom Dockerfiles. common

Why Use Docker? Benefits and Advantages ExplainedWhy Use Docker? Benefits and Advantages ExplainedApr 25, 2025 am 12:05 AM

The reason for using Docker is that it provides an efficient, portable and consistent environment to package, distribute, and run applications. 1) Docker is a containerized platform that allows developers to package applications and their dependencies into lightweight, portable containers. 2) It is based on Linux container technology and joint file system to ensure fast startup and efficient operation. 3) Docker supports multi-stage construction, optimizes image size and deployment speed. 4) Using Docker can simplify development and deployment processes, improve efficiency and ensure consistency across environments.

Docker in Action: Real-World Examples and Use CasesDocker in Action: Real-World Examples and Use CasesApr 24, 2025 am 12:10 AM

Docker's application scenarios in actual projects include simplifying deployment, managing multi-container applications and performance optimization. 1.Docker simplifies application deployment, such as using Dockerfile to deploy Node.js applications. 2. DockerCompose manages multi-container applications, such as web and database services in microservice architecture. 3. Performance optimization uses multi-stage construction to reduce the image size and monitor the container status through health checks.

Docker vs. Kubernetes: Use Cases and ScenariosDocker vs. Kubernetes: Use Cases and ScenariosApr 23, 2025 am 12:11 AM

Select Docker in a small project or development environment, and Kubernetes in a large project or production environment. 1.Docker is suitable for rapid iteration and testing, 2. Kubernetes provides powerful container orchestration capabilities, suitable for managing and expanding large applications.

Docker on Linux: Containerization for Linux SystemsDocker on Linux: Containerization for Linux SystemsApr 22, 2025 am 12:03 AM

Docker is important on Linux because Linux is its native platform that provides rich tools and community support. 1. Install Docker: Use sudoapt-getupdate and sudoapt-getinstalldocker-cedocker-ce-clicotainerd.io. 2. Create and manage containers: Use dockerrun commands, such as dockerrun-d--namemynginx-p80:80nginx. 3. Write Dockerfile: Optimize the image size and use multi-stage construction. 4. Optimization and debugging: Use dockerlogs and dockerex

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

mPDF

mPDF

mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

Safe Exam Browser

Safe Exam Browser

Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

SecLists

SecLists

SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

SAP NetWeaver Server Adapter for Eclipse

SAP NetWeaver Server Adapter for Eclipse

Integrate Eclipse with SAP NetWeaver application server.