Linux生成key

[root@centos7 ~]# ssh-keygen -b [ 2048 -t rsa  #这里的-b 2048 是密钥加密的长度，最好设大点
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
/root/.ssh/id_rsa already exists.
Overwrite (y/n)? y
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:TydATlOwdC66CUu6o7thGHI1ZwXnaCqsDOuDKtthx3k root@centos7.magedu.com
The key's randomart image is:
+---[RSA 2048]----+
|      ..Ooo      |
|       X =       |
|    o = * .      |
| . . * . o       |
|+ + + . S o .    |
|== = + o o o     |
|*o+ = E   .      |
|==.+ .           |
|O*+.             |
+----[SHA256]-----+
[root@centos7 ~]# cd /root/.ssh  #key文件会保存在/root/.ssh目录下
[root@centos7 ~/.ssh]# ls
authorized_keys  id_rsa （#私钥文件）  id_rsa.pub）（#公钥文件，这个文件里的内容要放到其它主机里面去。）
  known_hosts
[root@centos7 ~/.ssh]# cat id_rsa.pub 
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDRbiHp1QZqiQdP+sCX9LuZutfLmDbJ6WFCW1kaHp2WtGtvBgI
zsxA0LKglJKXdy2B/lUXXYQrpaNV2gT4fJDHAUFwq6NszUSwF2/6mW0T4lEt2SIWEVpbinYrmDxi0khgjuvzwcC
VButqtjUCJbE6Cg0Lc+0PS5Jha+QyCdKiOmCBKJlSdT5do9HEOdmhU96/jV+Km+h0mJBdTwS3JxcYrZoFCJBDpQ
ucs+gZSJvSwgSO57iZYoJHRiOfRzqVuE5PDbMf6bCaQ2yOoGOH/nWNqttozScEIcSsWbxTtPpIqVtmNwFhCy7Vg
O7sX+98iubPzGG7+PAiT1wbWtOIfpnWz root@centos7.magedu.com