问题描述：我在用kubeadm方式部署k8s，安装pod网络插件的时候出现以下报错

[root@master k8s]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/a70459be0084506e4ec919aa1c114638878db11b/Documentation/kube-flannel.yml

The connection to the server raw.githubusercontent.com was refused - did you specify the right host or port?

问题分析：基本上是因为连不上外网导致，所以我们添加映射

[root@master k8s]# echo "199.232.68.133 raw.githubusercontent.com" >> /etc/hosts

下载还是报错

[root@master k8s]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/a70459be0084506e4ec919aa1c114638878db11b/Documentation/kube-flannel.yml

The connection to the server raw.githubusercontent.com was refused - did you specify the right host or port?

改用wget下载方式成功

[root@master k8s]# wget https://raw.githubusercontent.com/coreos/flannel/a70459be0084506e4ec919aa1c114638878db11b/Documentation/kube-flannel.yml
--2021-09-29 20:09:59--  https://raw.githubusercontent.com/coreos/flannel/a70459be0084506e4ec919aa1c114638878db11b/Documentation/kube-flannel.yml
正在解析主机 raw.githubusercontent.com (raw.githubusercontent.com)... 199.232.68.133
正在连接 raw.githubusercontent.com (raw.githubusercontent.com)|199.232.68.133|:443... 已连接。
已发出 HTTP 请求，正在等待回应... 200 OK
长度：10599 (10K) [text/plain]
正在保存至: “kube-flannel.yml”

100%[=================================================================================================================================>] 10,599      --.-K/s 用时 0.01s   

2021-09-29 20:10:00 (917 KB/s) - 已保存 “kube-flannel.yml” [10599/10599])

[root@master k8s]# ls
kube-flannel.yml
[root@master k8s]# kubectl apply -f kube-flannel.yml 
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds-amd64 created
daemonset.extensions/kube-flannel-ds-arm64 created
daemonset.extensions/kube-flannel-ds-arm created
daemonset.extensions/kube-flannel-ds-ppc64le created
daemonset.extensions/kube-flannel-ds-s390x created