1、问题：

前几天我在的Linux mint 主机qwfys的Virtualbox 上新安装了一个Fedora27 系统，主机名取名为fefora。

将本地.ssh目录上传到fedora上：

lwk@qwfys ~ $ scp -r .ssh lwk@fedora:~/
id_rsa.pub                                    100%  397     0.4KB/s   00:00    
known_hosts                                   100% 6547     6.4KB/s   00:00    
id_rsa                                        100% 1675     1.6KB/s   00:00    
lwk@qwfys ~ $

登录到主机fedora上，

lwk@qwfys ~ $ ssh lwk@fedora 
Last login: Sat Dec 30 15:45:36 2017 from 192.168.1.4
lwk@redora ~ $

切换到目录~/~/Public/project/com/gitee下，将clone Spring boot 项目源码:

lwk@redora ~ $ cd Public/project/com/gitee/
lwk@redora ~/Public/project/com/gitee $ ll
total 8
drwxrwxr-x. 2 lwk lwk 4096 Dec 30 16:07 .
drwxrwxr-x. 3 lwk lwk 4096 Dec 30 15:54 ..
lwk@redora ~/Public/project/com/gitee $ 
lwk@redora ~/Public/project/com/gitee $ git clone [email protected]:spring-projects/spring-boot.git
Cloning into 'spring-boot'...
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Permissions 0644 for '/home/lwk/.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 "/home/lwk/.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.
lwk@redora ~/Public/project/com/gitee $

2、解决办法

经查资料，发现已经有人找到了问题的解决办法：

仔细阅读了一下ssh文档和这句提示，大概的意思时ssh的私有密钥的权限开放尺度太大了，可以供人随意>欣赏了，ssh自身的策略关闭了ssh。
解决方案：将权限由0644降低为0600
chmod 0600 ~/.ssh/id_rsa

这时回过头来查看~/.ssh目录下相关文件的权限：

lwk@redora ~/.ssh $ ll
total 28
drwx------.  2 lwk lwk 4096 Dec 29 18:26 .
drwx------. 10 lwk lwk 4096 Dec 30 15:21 ..
-rw-------.  1 lwk lwk  397 Dec 29 16:15 authorized_keys
-rw-r--r--.  1 lwk lwk 1675 Dec 30 16:08 id_rsa
-rw-r--r--.  1 lwk lwk  397 Dec 30 16:08 id_rsa.pub
-rw-r--r--.  1 lwk lwk 6547 Dec 30 16:08 known_hosts
lwk@redora ~/.ssh $

果然如此，现根据上面的提示将id_rsa、id_rsa.pub、known_hosts的权限修改为只有自己可以读写。

lwk@redora ~/.ssh $ chmod go+r id_rsa*
lwk@redora ~/.ssh $ chmod go+r known_hosts
lwk@redora ~/.ssh $ ll
total 28
drwx------.  2 lwk lwk 4096 Dec 29 18:26 .
drwx------. 10 lwk lwk 4096 Dec 30 15:21 ..
-rw-------.  1 lwk lwk  397 Dec 29 16:15 authorized_keys
-rw-------.  1 lwk lwk 1675 Dec 30 16:08 id_rsa
-rw-------.  1 lwk lwk  397 Dec 30 16:08 id_rsa.pub
-rw-------.  1 lwk lwk 6547 Dec 30 16:08 known_hosts

切换目录到~/Public/project/com/gitee，继续clone

lwk@redora ~ $ cd Public/project/com/gitee/
lwk@redora ~/Public/project/com/gitee $ git clone [email protected]:spring-projects/spring-boot.git
Cloning into 'spring-boot'...
remote: Counting objects: 318361, done.
remote: Compressing objects: 100% (323/323), done.

至此问题解决。

3、总结

出现这种情况主要还是由于初学者不熟悉Linux操作命令而导致的，如果能熟练使用ssh-copy-id就不会出现这样的问题，具体命令如下：

lwk@qwfys ~ $ ssh-copy-id -i ~/.ssh/id_rsa.pub lwk@fedora
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/home/lwk/.ssh/id_rsa.pub"
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
lwk@ubuntu's password: 

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'lwk@fedora'"
and check to make sure that only the key(s) you wanted were added.

lwk@qwfys ~ $

参考文献：
https://www.cnblogs.com/litifeng/p/5700892.html