SSH无密码设置

1. 生成公钥/私钥对

$ ssh-keygen -t rsa -P ''
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/double/.ssh/id_rsa): 
Your identification has been saved in /Users/double/.ssh/id_rsa.
Your public key has been saved in /Users/double/.ssh/id_rsa.pub.
The key fingerprint is:
1c:c2:c0:35:fb:8b:e4:ae:0e:a4:21:0b:e5:f2:6a:fc double@double.local
The key's randomart image is:
+--[ RSA 2048]----+
|   ...o          |
|    .o o         |
|  .   + .        |
| o     + .       |
|= o   . S        |
|oB   o . .       |
|+ o   o .        |
| + . .           |
|o .Eo..          |
+-----------------+

-P表示密码，-P '' 就表示空密码，也可以不用-P参数，这样就要三车回车，用-P就一次回车。
它在$HOME下生成.ssh目录，.ssh下有id_rsa和id_rsa.pub

$ ls
id_rsa		id_rsa.pub	known_hosts

2. 将id_rsa.pub写入到.ssh/authorized_keys

$ cat id_rsa.pub >> authorized_keys

3. 登陆测试

$ ssh localhost
Last login: Sat Apr  6 14:13:17 2013