linux多節點之間可以實現無密碼SSH相互遠程登錄。原理就是在每一個節點上面用ssky-keygen生成自己的公鑰和私鑰，然後再把自己的公鑰分別導入到其它節點上面，就可以實現無密碼遠程登錄了。
ssh-keygen 創建公鑰和密鑰。
ssh-copy-id 把本地主機的公鑰複製到遠程主機的authorized_keys文件上。
ssh-copy-id 也會給遠程主機的用戶主目錄（home）和~/.ssh, 和~/.ssh/authorized_keys設置合適的權限 。
（1）用 ssh-key-gen 在本地主機上創建公鑰和密鑰
ligh@local-host$ ssh-keygen -t rsa
Enter file in which to save the key (/home/jsmith/.ssh/id_rsa):[Enter key]
Enter passphrase (empty for no passphrase): [Press enter key]
Enter same passphrase again: [Pess enter key]
Your identification has been saved in /home/jsmith/.ssh/id_rsa.
Your public key has been saved in /home/jsmith/.ssh/id_rsa.pub.
The key fingerprint is: 33:b3:fe:af:95:95:18:11:31:d5:de:96:2f:f2:35:f9
（2）用 ssh-copy-id 把公鑰複製到遠程主機上
ligh@local-host$ssh-copy-id -i ~/.ssh/id_rsa.pub [email protected]
ligh@remote-host‘s password:
Now try logging into the machine, with ―ssh ?remote-host‘‖, and check in:
.ssh/authorized_keys to make sure we haven‘t added extra keys that you weren‘t expecting.
注: ssh-copy-id 可把公鑰密鑰追加到遠程主機的 .ssh/authorized_key文件中
如果提示：-bash: ssh-copy-id: command not found 是說明在改系統上沒有該命令，此命令是由openssh-clients包安裝的，在操作系統的光碟中有此包，也可以yum install openssh-clients安裝。
[root@centos ~]# which ssh-copy-id
/usr/bin/ssh-copy-id
[root@centos ~]# rpm -qf /usr/bin/ssh-copy-id
openssh-clients-5.3p1-84.1.el6.x86_64
（3） 遠程登入
ligh@local-host$ ssh remote-host
Last login: Sun Nov 16 17:22:33 2008 from 192.168.1.2
注: SSH 不會詢問密碼了即可遠程登錄主機