解决docker容器不能连接网络

1、问题描述：新建docker容器docker run -it --rm ubuntu:18.04执行apt update，报错：bash: ping: command not foundroot@d087aa834821:/# apt updateIgn:1 http://security.ubuntu.com/ubuntu bionic-security InReleaseIgn:2 http

南极浮冰

10104人浏览 · 2021-03-28 15:59:03

南极浮冰 · 2021-03-28 15:59:03 发布

1、问题描述：

新建docker容器
```
docker run -it --rm ubuntu:18.04
```

执行apt update，报错：

bash: ping: command not found
root@d087aa834821:/# apt update
Ign:1 http://security.ubuntu.com/ubuntu bionic-security InRelease
Ign:2 http://archive.ubuntu.com/ubuntu bionic InRelease
Ign:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease
Err:4 http://security.ubuntu.com/ubuntu bionic-security Release
  404   [IP: 91.189.91.38 80]
Ign:5 http://archive.ubuntu.com/ubuntu bionic-backports InRelease
Err:6 http://archive.ubuntu.com/ubuntu bionic Release
  404   [IP: 91.189.88.142 80]
Err:7 http://archive.ubuntu.com/ubuntu bionic-updates Release
  404   [IP: 91.189.88.142 80]
Err:8 http://archive.ubuntu.com/ubuntu bionic-backports Release
  404   [IP: 91.189.88.142 80]
Reading package lists... Done
E: The repository 'http://security.ubuntu.com/ubuntu bionic-security Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://archive.ubuntu.com/ubuntu bionic Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://archive.ubuntu.com/ubuntu bionic-updates Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://archive.ubuntu.com/ubuntu bionic-backports Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

2、解决方法：

方法1：新建docker时指定参数--network=host：

docker run -itd --rm --network=host ubuntu:18.04 /bin/bash

方法2：重置docker0（ docker0为docker的默认网桥）

# 杀死docker进程
pkill docker 
# 清空nat表的所有链
iptables -t nat -F
#停止docker默认网桥
ifconfig docker0 down
#删除docker默认网桥
brctl delbr docker0 
# 
docker -d 
#重启docker
systemctl restart docker

查看网络基本信息
```
ifconfig
```
查看网桥
```
brctl show
```

方法3：修改docker默认配置文件

查看文件/etc/default/docker
```
vi /etc/default/docker
```

文件内容中的DOCKER_OPTS选项为：

DOCKER_OPTS =“-dns 8.8.8.8 –dns 8.8.4.4”

查看本机dns
```
cat /etc/resolv.conf
```

输出为：

# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "systemd-resolve --status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver 127.0.0.53
options edns0

很明显docker参数中的dns地址与本机实际地址不一致，此时只需要注释掉DOCKER_OPTS参数即可。