以centos7系统为例，两台服务器之间（多台配置一样）进行服务器免密码登录配置：
test1主机免密码登录reserve5主机配置如下：
1. 制作密钥文件：
[root@test1 ~]# cd .ssh/
[root@test1 .ssh]# ls
authorized_keys known_hosts
[root@test1 .ssh]# 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):
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:FaJD4yiMN4S1KxcVjEe+AGgnezpyTYpgEfmdawWHFUg root@test1
The key's randomart image is:
+---[RSA 2048]----+
|o+=+=E*oo . |
|oX.=oB + . . |
|o #.+ B . |
|.+ O.+ o . |
|+.=+. o S |
|o=o .o |
|... . |
| |
| |
+----[SHA256]-----+
2.把制作好的密钥文件拷贝到需要免密登录的服务器主机：
[root@test1 .ssh]# ssh-copy-id root@主机ip地址
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
/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@主机ip地址's password:
Number of key(s) added: 1
Now try logging into the machine, with: "ssh 'root@reserve5主机ip地址'"
and check to make sure that only the key(s) you wanted were added.
3.验证是否可以免密码登录reserve5服务器主机
[root@test1 ~]# ssh 主机ip地址
Last failed login: Thu Mar 11 09:08:34 CST 2021 from xx.xxx.xx.xxx on ssh:notty
There were 31 failed login attempts since the last successful login.
Last login: Thu Mar 11 08:52:36 2021 from test主机IP地址
Welcome to JDCLOUD Elastic Compute Service
[root@reserve5 ~]# ifconfig
。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。
上述可知：免密码登录成功！