最佳方式：
1. sudo apt-get update
2. 安裝ssh
sudo apt-get install openssh-server
3. 生成公鑰
ssh-keygen -t rsa
以上3步驟AB機器均需要實現（已完成12步驟的可以只進行3）
在主機A上實現：
4. cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
5. ssh 192.168.1.148 cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
6. scp ~/.ssh/authorized_keys 192.168.1.148:~/.ssh/authorized_keys
7. 修改文件權限
cd ~/.ssh
sudo chmod 755 .ssh 以及 sudo chmod 644 authorized_keys
8. ssh-add
這樣A便能ssh無密碼訪問B，其中192.168.1.148爲主機B的ip地址
若要實現Bssh無密碼訪問A，則需要在主機B上執行4-8步驟
實際場景（採用鏈接1）：
hadoop@Slave1-hadoop:~$ sudo service ssh start
[sudo] password for hadoop:start: Job is already running: ssh
hadoop@Slave1-hadoop:~$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/hadoop/.ssh/id_rsa):
Created directory '/home/hadoop/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/hadoop/.ssh/id_rsa.
Your public key has been saved in /home/hadoop/.ssh/id_rsa.pub.
The key fingerprint is:
42:49:47:44:69:f6:b1:13:ae:e5:28:23:5f:f6:74:9b hadoop@Slave1-hadoop
The key's randomart image is:
+--[ RSA 2048]----+
| .+=. |
| . o+ o |
| oo o + |
| . * |
| . S= . |
| . o.= o . |
| o = o . o |
| . . E |
| |
+-----------------+
hadoop@Slave1-hadoop:~$ cd .ssh
hadoop@Slave1-hadoop:~/.ssh$ cat id_rsa.pub >> authorized_keys
hadoop@Slave1-hadoop:~/.ssh$ scp id_rsa.pub 166.111.82.38@Slave2-hadoop:/home/hadoop/id_rsa.pub
參考鏈接：
1.http://jingyan.baidu.com/article/3f16e003c918092591c103a2.html
2. http://www.it165.net/os/html/201311/6595.html