ssh免密码登录配置方法

首先,说明一下我们要做的是,serverA 服务器的 usera 用户免密码登录 serverB 服务器的 userb用户。

我们先使用usera 登录 serverA 服务器

 

  1.  [root@serverA ~]# su - usera
  2.  [usera@serverA ~]$ pwd
  3.  /home/usera

 

然后在serverA上生成密钥对

 

  1.  [usera@serverA ~]$ ssh-keygen -t rsa
  2.  Generating public/private rsa key pair.
  3.  Enter file in which to save the key (/home/usera/.ssh/id_rsa):
  4.  Created directory '/home/usera/.ssh'.
  5.  Enter passphrase (empty for no passphrase):
  6.  Enter same passphrase again:
  7.  Your identification has been saved in /home/usera/.ssh/id_rsa.
  8.  Your public key has been saved in /home/usera/.ssh/id_rsa.pub.
  9.  The key fingerprint is:
  10.  39:f2:fc:70:ef:e9:bd:05:40:6e:64:b0:99:56:6e:01 usera@serverA
  11.  The key's randomart image is:
  12.  +--[ RSA 2048]----+
  13.  | Eo* |
  14.  | @ . |
  15.  | = * |
  16.  | o o . |
  17.  | . S . |
  18.  | + . . |
  19.  | + . .|
  20.  | + . o . |
  21.  | .o= o. |
  22.  +-----------------+



 

此时会在/home/usera/.ssh目录下生成密钥对

 

  1.  [usera@serverA ~]$ ls -la .ssh
  2.  总用量 16
  3.  drwx------ 2 usera usera 4096 8月 24 09:22 .
  4.  drwxrwx--- 12 usera usera 4096 8月 24 09:22 ..
  5.  -rw------- 1 usera usera 1675 8月 24 09:22 id_rsa
  6.  -rw-r--r-- 1 usera usera 399 8月 24 09:22 id_rsa.pub

 

然后将公钥上传到serverB 服务器的,并以userb用户登录

 

  1.  [usera@portalweb1 ~]$ ssh-copy-id userb@10.124.84.20
  2.  The authenticity of host '10.124.84.20 (10.124.84.20)' can't be established.
  3.  RSA key fingerprint is f0:1c:05:40:d3:71:31:61:b6:ad:7c:c2:f0:85:3c:cf.
  4.  Are you sure you want to continue connecting (yes/no)? yes
  5.  Warning: Permanently added '10.124.84.20' (RSA) to the list of known hosts.
  6.  userb@10.124.84.29's password:
  7.  Now try logging into the machine, with "ssh 'userb@10.124.84.20'", and check in:
  8.  
     
  9.  .ssh/authorized_keys
  10.  
     
  11.  to make sure we haven't added extra keys that you weren't expecting.


 

这个时候usera的公钥文件内容会追加写入到userb的 .ssh/authorized_keys 文件中

 

  1.  [usera@serverA ~]$ cat .ssh/id_rsa.pub
  2.  ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEA2dpxfvifkpswsbusPCUWReD/mfTWpDEErHLWAxnixGiXLvHuS9QNavepZoCvpbZWHade88KLPkr5XEv6M5RscHXxmxJ1IE5vBLrrS0NDJf8AjCLQpTDguyerpLybONRFFTqGXAc/ximMbyHeCtI0vnuJlvET0pprj7bqmMXr/2lNlhIfxkZCxgZZQHgqyBQqk/RQweuYAiuMvuiM8Ssk/rdG8hL/n0eXjh9JV8H17od4htNfKv5+zRfbKi5vfsetfFN49Q4xa7SB9o7z6sCvrHjCMW3gbzZGYUPsj0WKQDTW2uN0nH4UgQo7JfyILRVZtwIm7P6YgsI7vma/vRP0aw== usera@serverA

 

查看serverB服务器userb用户下的 ~/.ssh/authorized_keys文件,内容是一样的,此处我就不粘贴图片了。

 

  1.  [userb@serverB ~]$ cat .ssh/authorized_keys
  2.  ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEA2dpxfvifkpswsbusPCUWReD/mfTWpDEErHLWAxnixGiXLvHuS9QNavepZoCvpbZWHade88KLPkr5XEv6M5RscHXxmxJ1IE5vBLrrS0NDJf8AjCLQpTDguyerpLybONRFFTqGXAc/ximMbyHeCtI0vnuJlvET0pprj7bqmMXr/2lNlhIfxkZCxgZZQHgqyBQqk/RQweuYAiuMvuiM8Ssk/rdG8hL/n0eXjh9JV8H17od4htNfKv5+zRfbKi5vfsetfFN49Q4xa7SB9o7z6sCvrHjCMW3gbzZGYUPsj0WKQDTW2uN0nH4UgQo7JfyILRVZtwIm7P6YgsI7vma/vRP0aw== usera@serverA

 

另外我们要注意,.ssh目录的权限为700,其下文件authorized_keys和私钥的权限为600。否则会因为权限问题导致无法免密码登录。我们可以看到登陆后会有known_hosts文件生成。

 

  1.  [useb@serverB ~]$ ls -la .ssh
  2.  total 24
  3.  drwx------. 2 useb useb 4096 Jul 27 16:13 .
  4.  drwx------. 35 useb useb 4096 Aug 24 09:18 ..
  5.  -rw------- 1 useb useb 796 Aug 24 09:24 authorized_keys
  6.  -rw------- 1 useb useb 1675 Jul 27 16:09 id_rsa
  7.  -rw-r--r-- 1 useb useb 397 Jul 27 16:09 id_rsa.pub
  8.  -rw-r--r-- 1 useb useb 1183 Aug 11 13:57 known_hosts

这样做完之后我们就可以免密码登录了

 

[usera@serverA ~]$ ssh userb@10.124.84.20


另外,将公钥拷贝到服务器的~/.ssh/authorized_keys文件中方法有如下几种:
1、将公钥通过scp拷贝到服务器上,然后追加到~/.ssh/authorized_keys文件中,这种方式比较麻烦。scp -P 22 ~/.ssh/id_rsa.pub user@host:~/。
2、通过ssh-copy-id程序,就是我演示的方法,ssh-copyid user@host即可
3、可以通过cat ~/.ssh/id_rsa.pub | ssh -p 22 user@host ‘cat >> ~/.ssh/authorized_keys’,这个也是比较常用的方法,因为可以更改端口号。

posted @ 2018-09-06 11:23  Xuwenxing  阅读(38926)  评论(0编辑  收藏