ssh-keygen+ssh-copy-id无密码登录远程LINUX主机（转载）

From：http://blog.163.com/lgh_2002/blog/static/44017526201011333227161/

1、创建公钥和私钥

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: :b3:fe:af::::::d5:de::2f:f2::f9
ligh@local-host

2、使用ssh-copy-id将公钥复制到远程主机

ligh@local-host$ ssh-copy-id -i ~/.ssh/id_rsa.pub  root@192.168.0.3
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.

3、直接登录远程主机

ligh@local-host$ ssh remote-host
Last login: Sun Nov  ::  from 192.168.1.2
ligh@remote-host$

ssh-keygen 创建公钥和密钥。 
ssh-copy-id 把本地主机的公钥复制到远程主机的authorized_keys文件上。
ssh-copy-id 也会给远程主机的用户主目录（home）和~/.ssh, 和~/.ssh/authorized_keys设置合适的权限 。