docker开放外部访问
首先备份docker文件：
cp /usr/lib/systemd/system/docker.service /usr/lib/systemd/system/docker.service_back编辑docker文件：/usr/lib/systemd/system/docker.service
vim /usr/lib/systemd/system/docker.service修改ExecStart行为下面内容
ExecStart=/usr/bin/dockerd -H tcp://0.0.0.0:2375 -H unix://var/run/docker.sock重新加载docker配置
systemctl daemon-reload // 1，加载docker守护线程
systemctl restart docker // 2，重启docker
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systemctl daemon-reload
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systemctl restart docker