一，原理

 

说明：

A为linux服务器a

B为linux服务器b

每台linux都有ssh的服务端和客户端，linux下的ssh命令就是一个客户端

我们常用ssh协议来进行登陆或者是文件的拷贝，都需要密码

A要免密登陆B：

1，需要在a中执行ssh-keygen生成自己的公钥和私钥,生成的文件在.ssh文件中。

2，需要吧a中的公钥copy到b中的中，b进行授权（把公钥中的信息拷贝到“authorized_keys”文件中）  这里只需要一个命令ssh-copy-id 命令

eg：

[eddy@eddy01 .ssh]$ ssh-keygen                                                     Generating public/private rsa key pair.Enter file in which to save the key (/home/eddy/.ssh/id_rsa): Enter passphrase (empty for no passphrase):           //直接回车Enter same passphrase again: 　　　　　　　　　　　　　　//直接回车Your identification has been saved in /home/eddy/.ssh/id_rsa.Your public key has been saved in /home/eddy/.ssh/id_rsa.pub.The key fingerprint is:58:e5:f9:58:27:b5:4e:dc:32:ce:6c:eb:56:ac:89:9b eddy@eddy01The key's randomart image is:+--[ RSA 2048]----+|          .   .  ||         o . o o ||        . o o B .||       o   + O o ||      . S . . *. ||             . .o||             ..+ ||            .o+  ||            Eo.  |+-----------------+[eddy@eddy01 .ssh]$ ssh-copy-id eddy02                                             eddy@eddy02's password: Now try logging into the machine, with "ssh 'eddy02'", and check in:  .ssh/authorized_keysto make sure we haven't added extra keys that you weren't expecting.[eddy@eddy01 .ssh]$ ssh eddy02Last login: Tue Mar  7 12:25:23 2017 from 192.168.145.1[eddy@eddy02 ~]$