ssh 免密码登入

1、普通免密码登入

(1)  生成秘钥

[root@vick ~]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Created directory '/root/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
67:c6:ca:04:ff:52:d7:e0:f2:14:f1:ae:55:cc:39:6b root@localhost.localdomain
The key's randomart image is:
+--[ RSA 2048]----+
|            .    |
|             o o.|
|      .     o .o+|
|       o . . = .o|
|        S B + +E |
|       o B = o.  |
|        + . o    |
|         .       |
|                 |
+-----------------+

执行完后 本地会生成公钥和私钥

[root@vick ~]# ls -l /root/.ssh/
-rw-------. 1 root root 1675 Aug 12 17:33 id_rsa
-rw-r--r--. 1 root root  408 Aug 12 17:33 id_rsa.pub

(2)  将公钥复制到远程主机

[root@vick ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub 192.168.88.180

(3)  启用认证代理

[root@vick ~]# ssh-agent bash

(4)  测试

远程主机上面会出现/root/.ssh/authorized_keys

OK 现在就实现免密码登入了

2、秘钥加密

(1)  同样先生成公钥和私钥

[root@vick ~]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase):     #输入密码
Enter same passphrase again: 　　　　　　　　　　　#再次输入密码
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
34:a7:99:96:7d:83:69:9a:53:df:82:ff:e4:a5:52:94 root@localhost.localdomain
The key's randomart image is:
+--[ RSA 2048]----+
|                 |
|                 |
|        o .    . |
|       . O o  E  |
|        S * o.   |
|       . = + o.  |
|        + . o.o .|
|         . ..+ o |
|            .o+  |
+-----------------+

执行完后会生成两个秘钥

[root@vick ~]# ls -l /root/.ssh/
-rw-------. 1 root root 1743 Aug 13 00:47 id_rsa
-rw-r--r--. 1 root root  408 Aug 13 00:47 id_rsa.pub

(2)  将公钥复制到远程主机

[root@vick ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub 192.168.88.180

(3)  启用认证代理

[root@vick ~]# ssh-agent bash

(4) 将私钥密码加入认证代理

[root@vick ~]# ssh-add
Enter passphrase for /root/.ssh/id_rsa:  #在这里输入加密密码
Identity added: /root/.ssh/id_rsa (/root/.ssh/id_rsa)

(5)测试

秘钥加密和不加密的区别：

第一种方法秘钥不加密，将生成的秘钥放在任何台设备上都，都可以实现免密登入，秘钥被盗取后 其他人一样能用改秘钥登入

第二种方法秘钥加密，只有本机生成的秘钥在本机才能实现免密码登入，就算秘钥被盗取，其他人也无法通过该秘钥登入 除非有加密密码