本地公钥登录服务器

1、修改配置

# sudo vim /etc/ssh/sshd_config

# 禁止密码登录
PasswordAuthentication no
#允许密钥认证
RSAAuthentication yes # 7.4之后废除
PubkeyAuthentication yes
#默认公钥存放的位置
AuthorizedKeysFile      .ssh/authorized_keys

2、重启sshd

service sshd restart

# 查看 ssh 状态
systemctl status sshd
# 启动 ssh
systemctl start sshd
# 停止 ssh
systemctl stop sshd

3、本地生成公钥、私钥

$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/jiqing/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/jiqing/.ssh/id_rsa.
Your public key has been saved in /home/jiqing/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:LDe1utjTXrLkuU961zkZdYI+yHaOcr0PLXTLYjRD0uE jiqing@JQ-Mac
The key's randomart image is:
+---[RSA 2048]----+
|            .    |
|           o .   |
|          o E.   |
|       . . +. . o|
|      . S..o= ..o|
|       o o+o+* o |
|        .oo=B.+.+|
|       oo++O++.+.|
|      . o=B+o+. .|
+----[SHA256]-----+

-rw-------  1 jiqing jiqing 1679 5月  28 17:05 id_rsa
-rw-r--r--  1 jiqing jiqing  395 5月  28 17:05 id_rsa.pub

4、用ssh-copy-id将公钥复制到远程机器中

ssh-copy-id -i ~/.ssh/id_rsa.pub root@线上IP

5、直接免密登录

ssh root@线上IP

我们发现线上的authorized_keys文件中有了秘钥

# cat authorized_keys 
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDDU3UxwVJVTqY80s9HhGrBue3PIbsvWuIkXxIokPLN8C6mSUW/PeJQ73jjp1ZXEEygePXkxAou7JsPBItHQ5C7U1Zg6rAt3x7JTccNjvoVIRRbpxLY4AK/qlr1nEHtLxGEfCTtZ4pVrtEyLXQDGYIS6lexvA96z9Z19YfZLRRkzbPp6Jud8kBG+j3hLAlfXMkB/+HJ6HFOQ7Sa5DUoZn98on0LvZPdThxwxBpLcNqjIZ3tiTUobnY1EKbi/8kcq9tS8vLoPFdsEQM4F3pe9P6cXQGaHy73z06/tWGfsVlGomJFSOrvNvtPXd/SsRRLrUMlE8yM7zQaoZULNG7KEVyb jiqing@JQ-Mac

$ cat id_rsa.pub 
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDDU3UxwVJVTqY80s9HhGrBue3PIbsvWuIkXxIokPLN8C6mSUW/PeJQ73jjp1ZXEEygePXkxAou7JsPBItHQ5C7U1Zg6rAt3x7JTccNjvoVIRRbpxLY4AK/qlr1nEHtLxGEfCTtZ4pVrtEyLXQDGYIS6lexvA96z9Z19YfZLRRkzbPp6Jud8kBG+j3hLAlfXMkB/+HJ6HFOQ7Sa5DUoZn98on0LvZPdThxwxBpLcNqjIZ3tiTUobnY1EKbi/8kcq9tS8vLoPFdsEQM4F3pe9P6cXQGaHy73z06/tWGfsVlGomJFSOrvNvtPXd/SsRRLrUMlE8yM7zQaoZULNG7KEVyb jiqing@JQ-Mac

我们删除一下authorized_keys试试，删除后发现无法登录了。