本文已参与[新人创作礼]活动，一起开启掘金创作之路。
本文介绍快速配置ssh无密码登录，看到很多文章介绍的配置无密码登录需要很多步骤，虽然不算麻烦，但是本身只需要一个命令就能够配置的东西却搞半天，实在是很烦，所以我就在这里整理记录了两种快速配置ssh无密码登录的方法。
前提：现在要配置A服务器免密码登录B服务器。
第一种方法： 在A服务器上执行ssh-keygen，一路按确定即可，如果已经生成过密码，甚至这一步都可以省略。 接着执行ssh-copy-id root@B服务器ip，输入B服务器的密码就配置完成了。下面是操作步骤：
[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:+FEfmqvoLiTOFp7hL+Ov8JiHHOvcYX0vYVWe5Fwpt+U
root@localhost.localdomain
The key's randomart image is:
+---[RSA 2048]----+
| . |
| + + . |
| B * + |
| . o O o E |
| . S o . |
| .+ o + . . |
|o*oO ...o . |
|oB& o .o.. |
|+*+Bo++ o. |
+----[SHA256]-----+
[root@localhost ~]# ssh-copy-id root@192.168.11.200
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host '192.168.11.200 (192.168.11.200)' can't be established.
ECDSA key fingerprint is SHA256:fmsVpyf+39IPGV5YNO+MlDvAOViAKcYPrrla4ihULxo.
ECDSA key fingerprint is MD5:77:c0:4a:1e:0b:b3:47:1c:a0:7b:97:8b:91:df:b2:1d.
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@192.168.11.200's password:
第二种方法： 同上一步执行ssh-keygen，一路确定生成密钥，将/root/.ssh/id_rsa.pub的内容复制出来。 在B服务器用户家目录（如果用的root用户登录就是/root目录），创建.ssh目录。将刚才A服务器的id_rsa.pub的内容复制到authorized_keys文件，如果没有该文件的话创建一个就可以。
