ssh免密码登陆

 有时候在运维过程中，需要连接N多机器进行故障排查，即使密码都相同，敲来敲去也很麻烦，所以有了下文。

A机器上的操作：

[root@localhost ~]# cd .ssh/
[root@localhost .ssh]# ll
总用量 4
-rw-r--r-- 1 root root 1179  3月 27 10:14 known_hosts
[root@localhost .ssh]# ssh-keygen -t rsa  ---生成密钥文件
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:
04:e8:26:15:76:ff:18:79:b5:4c:09:b7:19:5b:5f:47 root@localhost
The key's randomart image is:
+--[ RSA 2048]----+
|    ooo   ..=...E|
|   .o. o . =.B .o|
|   o    = . *   .|
|  . o  . =       |
|   o    S .      |
|                 |
|                 |
|                 |
|                 |
+-----------------+
[root@localhost .ssh]# ll
总用量 12
-rw------- 1 root root 1675  9月 25 14:35 id_rsa
-rw-r--r-- 1 root root  396  9月 25 14:35 id_rsa.pub
-rw-r--r-- 1 root root 1179  3月 27 10:14 known_hosts
[root@localhost .ssh]# scp id_rsa.pub [email protected]:/root/.ssh/
The authenticity of host '192.168.7.7 (192.168.7.7)' can't be established.
RSA key fingerprint is 9d:95:85:d6:77:9b:d8:56:23:9b:0d:5c:95:22:c9:84.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.7.7' (RSA) to the list of known hosts.
[email protected]'s password:
scp: /root/.ssh/: Is a directory  ---B机器没有.ssh目录
[root@localhost .ssh]# scp id_rsa.pub [email protected]:/root/.ssh/
[email protected]'s password:
id_rsa.pub                                            100%  396     0.4KB/s   00:00      ---向B机器拷贝生成的密钥文件

B机器上的操作：

[root@Cacti ~]# ls -lart
total 40
-rw-r--r--.  1 root root  100 Sep 23  2004 .cshrc
-rw-r--r--.  1 root root  129 Dec  4  2004 .tcshrc
-rw-r--r--.  1 root root  176 May 20  2009 .bash_profile
-rw-r--r--.  1 root root   18 May 20  2009 .bash_logout
-rw-------   1 root root  568 Sep 19 14:51 .mysql_history
-rw-r--r--   1 root root  191 Sep 19 14:52 .bashrc
-rw-------   1 root root 1039 Sep 21 16:54 .viminfo
dr-xr-xr-x. 22 root root 4096 Sep 24 14:37 ..
-rw-------   1 root root 1947 Sep 25 15:24 .bash_history
dr-xr-x---.  2 root root 4096 Sep 25 15:25 .
[root@Cacti ~]# mkdir .ssh
[root@Cacti ~]# cd .ssh/  ----A机器向B机器拷贝密钥文件
[root@Cacti .ssh]# ll
total 4
-rw-r--r-- 1 root root 396 Sep 25 15:26 id_rsa.pub
[root@Cacti .ssh]# mv id_rsa.pub authorized_keys
[root@Cacti .ssh]# chmod 600 /root/.ssh/authorized_keys
[root@Cacti .ssh]#

 操作完以上后，再来从A机器登陆B机器试试看：

操作完成后，做下免密码登陆测试：
[root@localhost .ssh]# ssh [email protected]
Last login: Tue Sep 25 14:32:47 2012 from 192.168.7.36
[root@Cacti ~]#   ----A机器登陆B已经不需要再输入密码了！