执行 docker run 时遇到如下WARNING：
[root@etcd1 volumes]# docker run -d -p 8080:80 -v /tmp/test_mount httpd
Unable to find image ‘httpd:latest‘ locally
Trying to pull repository docker.io/library/httpd ...
sha256:72f2b4aa99235509146bd12054d1a93c1c869ba60212d21729118c93ca4305d3: Pulling from docker.io/library/httpd
3d77ce4481b1: Pull complete
73674f4d9403: Pull complete
d266646f40bd: Pull complete
ce7b0dda0c9f: Pull complete
01729050d692: Pull complete
014246127c67: Pull complete
7cd2e04cf570: Pull complete
Digest: sha256:72f2b4aa99235509146bd12054d1a93c1c869ba60212d21729118c93ca4305d3
Status: Downloaded newer image for docker.io/httpd:latest
WARNING: IPv4 forwarding is disabled. Networking will not work.
a281f3580d29863a472a3d8c5945a07c0b9d485dcd49f50b3816ff6406e44513
查看 IPv4 forwarding 启用情况
[root@etcd1 volumes]# sysctl net.ipv4.ip_forward net.ipv4.ip_forward = 0
解决方案：
[root@etcd1 volumes]# echo net.ipv4.ip_forward=1 >> /usr/lib/sysctl.d/00-system.conf [root@etcd1 volumes]# systemctl restart network
查看是否修改成功：
[root@etcd1 volumes]# sysctl net.ipv4.ip_forward net.ipv4.ip_forward = 1
重启docker服务：
[root@etcd1 volumes]# systemctl restart docker
完成！
docker run 报错——WARNING: IPv4 forwarding is disabled. Networking will not work.
原文：https://www.cnblogs.com/cxbhakim/p/9144343.html