OpenSSH Service(SSH Service)-基于Key秘钥对验证(免密登录)

基于Password认证请参考文件：

OpenSSH Service(SSH Service)-基于Password认证

        SSH为Sec […]

配置方法：
1、登陆服务器利用命令（ssh-keygen）生成密钥对，默认回车直到结束；在登录用户家目录（/UserHome/.ssh）下生成公钥(id_rsa.pub)文件和私钥(id_rsa)文件；公钥文件是用于服务器端，私钥文件是用于客户端；将私钥下载至本地电脑上(第三方软件登录时会用到)。

[root@localhost ~]# ssh-keygen 
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:
SHA256:nvp8CzSb43wQnBa14gL42Q6FBp2XurM028XWo8i/Tec root@localhost.localdomain
The key's randomart image is:
+---[RSA 2048]----+
|  .. . . ..      |
|   oo.o .  .     |
|  . +o...o.      |
|   o.= .=.       |
|    +.ooSo       |
|    =o +==o      |
|   . B.+Bo...    |
|    o +=.=oo     |
|      .oB+o.E    |
+----[SHA256]-----+

[root@localhost ~]# ll .ssh/
total 8
-rw------- 1 root root 1679 Mar  8 00:30 id_rsa
-rw-r--r-- 1 root root  408 Mar  8 00:30 id_rsa.pub

2、将公钥文件上传至服务器端：ssh-copy-id UserName@Server-IP  #自动创建密钥验证文件(authorized_keys)并把公钥信息写入进该文件内

[root@localhost ~]# ssh-copy-id root@192.168.80.247
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host '192.168.80.247 (192.168.80.247)' can't be established.
ECDSA key fingerprint is SHA256:2Eo2WLWyofiltEAs4nLUFLOcXLFD6YvsuPSDlEDUZGk.
ECDSA key fingerprint is MD5:3c:b0:5f:a8:af:6a:15:45:eb:a9:2a:b0:20:21:65:04.
Are you sure you want to continue connecting (yes/no)? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
root@192.168.80.247's password: 

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'root@192.168.80.247'"
and check to make sure that only the key(s) you wanted were added.

3、编辑修改SSH服务端配置文件（/etc/ssh/sshd_config）确保参数开启无误：
RSAAuthentication yes 开启RSA验证
PubkeyAuthentication yes 是否使用公钥验证
PS：
    1、CentOS7系列系统默认已开启了相关配置可忽略此步骤
    2、如修改了配置文件请重启服务生效：systemctl restart sshd.service
4、验证登录：此时已无需密码验证直接登录了

[root@localhost ~]# ssh root@192.168.80.247
Last login: Sun Mar  7 23:29:42 2021 from 192.168.80.105
[root@ceph3 ~]#

[root@ceph3 ~]# ll -d .ssh/
drwx------ 2 root root 29 Feb 26 02:41 .ssh/
[root@ceph3 ~]# ll .ssh/authorized_keys 
-rw------- 1 root root 1003 Mar  8 00:36 .ssh/authorized_keys