复制.ssh文件夹重用ssh key时，可能出现权限问题，导致ssh链接被拒。
git clone ssh://Admin@192.168.64.68:29418/mesos/jenkins-on-mesos
正克隆到 'jenkins-on-mesos'...
The authenticity of host '[192.168.64.68]:29418 ([192.168.64.68]:29418)' can't be established.
ECDSA key fingerprint is SHA256:MmFho1QRFeDMOHww2JUclzwTA1pSUw5odhRX330vWII.
ECDSA key fingerprint is MD5:87:b0:5b:d0:27:5f:8f:3e:f1:92:fa:72:2d:6c:15:3e.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '[192.168.64.68]:29418' (ECDSA) to the list of known hosts.
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@ WARNING: UNPROTECTED PRIVATE KEY FILE! @
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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).
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.
Permissions 0644 for '/root/.ssh/id_rsa' are too open.
- 解决方案：将权限由0644降低为0600
chmod 0600 ~/.ssh/id_rsa