ssh免秘钥登录远程服务器

1. 生成公钥
   使用命令

   ssh-keygen -t rsa

   然后一路回车，会在家目录文件夹下生成.ssh文件，并且在里面生成公钥和密钥等文件，将公钥传到服务器要登录账户的对应位置就行了。
   会生成如下所示

   Generating public/private rsa key pair.
   Enter file in which to save the key (/home/js/.ssh/id_rsa): 
   Enter passphrase (empty for no passphrase): 
   Enter same passphrase again: 
   Your identification has been saved in /home/js/.ssh/id_rsa.
   Your public key has been saved in /home/js/.ssh/id_rsa.pub.
   The key fingerprint is:
   SHA256:UYbqIa81msdH06HNqzvyq1k8TZC/Vkn+siu/UzrMoHI js@js-PC
   The key's randomart image is:
   +---[RSA 2048]----+
   |         .o      |
   |        .+       |
   |       .+   .    |
   |    . o  +.o .   |
   |     + .S=o.+    |
   |      =.+o=o ..  |
   |     * o+o+=.o.  |
   |    + =oEoo *o   |
   |     .oB== o==   |
   +----[SHA256]-----+
   

2. 传送公钥
   先将公钥传输上服务器，然后将文件内容追加在服务器的.ssh/authorized_keys中。注意，是追加，不要覆盖别人的。

   scp .ssh/id_rsa.pub bbs:pub_key
   ssh bbs
   cat ~/pub_key >> authorized_keys

   然后保证服务器上的文件权限是正确的

   1) .ssh目录的权限必须是700 
   2) .ssh/authorized_keys文件权限必须是600

   ---

   参考文献
   Linux下实现免密码登录(超详细) http://www.jb51.net/article/94599.htm