* ssh 多台服务器之间连接

例如有4台机器，需要相互之间不使用密码通信。
|----------+-------------|
| host     |    IP       |
|----------+-------------|
| server01 | 192.168.0.1 |
| server02 | 192.168.0.2 |
| server03 | 192.168.0.3 |
| server04 | 192.168.0.4 |
|----------+-------------|

** 第一步：生成各自的文件夹

server01:# mkdir -p /root/.ssh; chmod 700 /root/.ssh
server02:# mkdir -p /root/.ssh; chmod 700 /root/.ssh
server03:# mkdir -p /root/.ssh; chmod 700 /root/.ssh
server04:# mkdir -p /root/.ssh; chmod 700 /root/.ssh

** 第二步： 生成各自的key

1. 分别进入/root/.ssh/目录，执行命令：
server01:# ssh-keygen -t rsa
server02:# ssh-keygen -t rsa 
server03:# ssh-keygen -t rsa 
server04:# ssh-keygen -t rsa

一路回车即可生成对应的key（private key: id_rsa  ) （ public key: id_rsa.pub ）

server01:# cp id_rsa.pub authorized_keys

server02:# cp id_rsa.pub authorized_keys

server03:# cp id_rsa.pub authorized_keys

server04:# cp id_rsa.pub authorized_keys

2. 四台服务器上分别执行下面买的命令
server01:# ssh-keygen -t rsa1 -f /etc/ssh/ssh_host_key -N ""
server01:# ssh-keygen -t rsa1 -f /etc/ssh/ssh_host_rsa_key -N ""
server01:# ssh-keygen -t dsa -f /etc/ssh/ssh_host_dsa_key -N ""
server01:# /etc/init.d/ssh restart

** 第三步： 添加不同服务器的public key(id_rsa.pub)到自己的authorized_keys文件中

(注意：下面的scp命令中还需要手动输入密码才能登陆)
server01:# scp 192.168.0.2:/root/.ssh/id_rsa.pub /root/
server01:# cat /root/id_rsa.pub >> /root/.ssh/authorized_keys

server01:# scp 192.168.0.3:/root/.ssh/id_rsa.pub /root/
server01:# cat /root/id_rsa.pub >> /root/.ssh/authorized_keys

server01:# scp 192.168.0.4:/root/.ssh/id_rsa.pub /root/
server01:# cat /root/id_rsa.pub >> /root/.ssh/authorized_keys

现在server01上的/root/.ssh/authorized_keys已经包含了四台服务器的public key。

server01:# scp /root/.ssh/authorized_keys scp 192.168.0.2:/root/.ssh/authorized_keys
server01:# scp /root/.ssh/authorized_keys scp 192.168.0.3:/root/.ssh/authorized_keys
server01:# scp /root/.ssh/authorized_keys scp 192.168.0.4:/root/.ssh/authorized_keys

至此，应该可以相互之间无密码连接了。

engoy it!