root@kali2:~/.ssh# ssh-keygen -t rsa

Generating public/private rsa key pair.

Enter file in which to save the key (/root/.ssh/id_rsa): 　　<-- 此处使用默认路径，直接回车

Enter passphrase (empty for no passphrase): 　　　　　　　　　　<-- 此处使用空密码，直接回车

Enter same passphrase again: 　　　　　　　　　　　　　　　　　　　<-- 继续回车

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:

e9::e1:c9::9e:cb:1e:ec::8c:e9:9a:a5::ff root@kali2

The key's randomart image is:

+---[RSA ]----+

|                 |

|                 |

|          .      |

|         + .     |

|        S+o      |

|       +o*o.     |

|      ..O =.     |

|       X.o ..    |

|      =...E.     |

+-----------------+

root@kali2:~/.ssh# ls -l

total

-rw-------  root root  Jul  : id_rsa

-rw-r--r--  root root   Jul  : id_rsa.pub

-rw-r--r--  root root   Jul  : known_hosts

root@kali2:~/.ssh# scp -r /root/.ssh/id_rsa.pub root@192.168.129.128:/root/.ssh

root@192.168.129.128's password:

id_rsa.pub                                                                                     %       .4KB/s   : 

[root@localhost .ssh]# ls

id_rsa.pub  known_hosts

[root@localhost .ssh]# touch authorized_keys

[root@localhost .ssh]# ls

authorized_keys  id_rsa.pub  known_hosts

[root@localhost .ssh]# cat id_rsa.pub >> ./authorized_keys

[root@localhost .ssh]# ls -l

total

-rw-r--r--.  root root  Jul  : authorized_keys

-rw-r--r--.  root root  Jul  : id_rsa.pub

-rw-r--r--.  root root  Jul  : known_hosts

root@kali2:~/.ssh# ssh 192.168.129.128

Last failed login: Tue Jul  :: CST  from 192.168.129.129 on ssh:notty

There was  failed login attempt since the last successful login.

Last login: Tue Jul  ::  from 192.168.129.129

[root@localhost ~]#

在使用公钥认证之前，先检查一下服务器的ssh配置文件/etc/ssh/sshd_config

RSAAuthentication yes        # 启用 RSA 认证，默认为yes

PubkeyAuthentication yes     # 启用公钥认证，默认为yes

如果安全性要求高，修改一下服务器的配置文件/etc/sshd/sshd_config，
禁用密码登录，只能通过公钥方式登录。

　　PasswordAuthentication no