设置密匙登录
使用下例中ssky-keygen和ssh-copy-id，仅需通过3个步骤的简单设置而无需输入密码就能登录远程Linux主机。
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 。ssh-key-gen 本地创建公钥和密钥
root@local-host$ ssh-keygen -i ~/.ssh/ansible -t rsa
Enter file in which to save the key (/root/.ssh/ansible):[Enter key]
Enter passphrase (empty for no passphrase): [Press enter key]
Enter same passphrase again: [Pess enter key]
Your identification has been saved in /root/.ssh/ansible.
Your public key has been saved in /root/.ssh/ansible.pub.
The key fingerprint is: 33:b3:fe:af:95:95:18:11:31:d5:de:96:2f:f2:35:f9
在脚本中生成秘钥公钥
上面方式需要有交互,无法在脚本中实现
#-t指定SSH密钥的算法为RSA算法，-N设置密码为空，-f指定生成的密钥文件存放位置
ssh-keygen -t rsa -n '' -f ~/.ssh/id_rsa
ssh-copy-id把公钥复制到远程主机上
root@local-host$ ssh-copy-id -i ~/.ssh/ansible.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. [注: ssh-copy-id 把密钥追加到远程主机的 .ssh/authorized_key 上.]
步骤3: 直接登录远程主机
root@local-host$ ssh 192.168.0.3 Last login: Sun Nov 16 17:22:33 2008 from 192.168.1.2
[注: SSH 不会询问密码.]
root@remote-host$ [注: 你现在已经登录到了远程主机上]
