[root@iZ28wg1kditZ .ssh]# cat /etc/exports
/     *(rw,sync,root_squash)[root@iZ28qsvv5siZ ~]# ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
/root/.ssh/id_rsa already exists.
Overwrite (y/n)?
[root@iZ28qsvv5siZ ~]# cat /root/.ssh/id_rsa.pub >>/tmp/test/root/.ssh/authorized_keys
-bash: /tmp/test/root/.ssh/authorized_keys: Permission denied
[root@iZ28qsvv5siZ ~]# 

[root@iZ28wg1kditZ .ssh]# cat /etc/exports
/     *(rw,sync,no_root_squash)[root@iZ28qsvv5siZ root]# ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
49:08:ff:93:12:d8:26:32:e5:1b:b7:b5:8f:3c:17:2c root@iZ28qsvv5siZ
The key's randomart image is:
+--[ RSA 2048]----+
|    o            |
|   o = .         |
|  o = B o        |
|   o * * =       |
|    . o E o      |
|       o = .     |
|        + o      |
|         o       |
|                 |
+-----------------+
[root@iZ28qsvv5siZ root]# cd ~
[root@iZ28qsvv5siZ ~]# cat .ssh/id_rsa.pub >>/tmp/test/root/.ssh/
id_rsa       id_rsa.pub   known_hosts
[root@iZ28qsvv5siZ ~]# cat .ssh/id_rsa.pub >>/tmp/test/root/.ssh/authorized_keys
[root@iZ28qsvv5siZ ~]# ssh root@xxx.xxx.xxx.xxx
Last login: Wed Aug  3 14:50:51 2016 from xxx.xxx.xxx.xxWelcome to aliyun Elastic Compute Service![root@iZ28wg1kditZ ~]# ls
axel-2.4-1.el5.rf.x86_64.rpm  ghost                         __MACOSX