Linux中Git推送报错Permissions 0644 for ‘/root/.ssh/id_rsa‘ are too open

准备在Linux上配置秘钥，方便Git上传代码到GitHub。

但是秘钥(id_rsa文件)是从本地Windows环境上传到Linux服务器上面的，在执行推送时报错了，如下：

# git push -u origin main
The authenticity of host 'github.com (20.205.243.166)' can't be established.
ECDSA key fingerprint is SHA256:p2QAMXNIC1TJYWeIOttrVc98/R1BUFWu3/LiyKgUfQM.
ECDSA key fingerprint is MD5:7b:99:81:1e:4c:91:a5:0d:5a:2e:2e:80:13:3f:24:ca.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'github.com,20.205.243.166' (ECDSA) to the list of known hosts.
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Permissions 0644 for '/root/.ssh/id_rsa' are too open.
It is required that your private key files are NOT accessible by others.
This private key will be ignored.
Load key "/root/.ssh/id_rsa": bad permissions
Permission denied (publickey).
致命错误：无法读取远程仓库。

请确认您有正确的访问权限并且仓库存在。

很明显，意思是该文件权限太大了，然后被拒绝操作了。（其实我感觉有点奇怪，好像管的有点宽，权限够你操作不就行了吗？还不能太高……）

虽然知道了问题所在，但是不清楚具体要调成啥权限，搜了下关键字，发现600权限就够了。

chmod 600 /root/.ssh/id_rsa