ubuntu root下的无密码登陆

以前都是两台机器在普通用户之间无密码登陆，今天两台机器都是root下配置无密码登陆，方法很简单，写下过程：

注：以root下节点c01无密码登陆c02为例

1.c01执行：ssh-keygen -t rsa，按y，enter，enter

root@c01:~# ssh-keygen -t rsa
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:
12:68:51:41:7a:72:65:ba:e7:d3:ab:d6:0f:3b:d4:f6 root@cloud
The key's randomart image is:
+--[ RSA 2048]----+
|    .o+.o        |
|     + +         |
|    = =          |
|   . + o         |
|      o S  .     |
|       + .. o    |
|        ooo. .   |
|        ..o+  E  |
|       ...oo.    |
+-----------------+

2.在c02上为root添加密码：passwd root，输入你的密码

root@c02:~/.ssh# passwd root
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully

3.把c01公钥传至c02，并命名authorized_keys,执行：scp /root/.ssh/id_rsa.pub [email protected]:/root/.ssh/authorized_keys,输入你的root密码，发送成功

4.co1上执行：ssh 172.18.48.5，就可以在root下直接c01无密码登陆c02了