[root@zshts011 backup]# telnet 192.168.31.42

Trying 192.168.31.42...

telnet: connect to address 192.168.31.42: No route to host

解决方法：

在目标机器上执行：iptables -F

[root@zshts011 backup]# telnet 192.168.31.42

Trying 192.168.31.42...

Connected to 192.168.31.42.

Escape character is '^]'.

Red Hat Enterprise Linux Server release 6.2 (Santiago)

Kernel 2.6.32-220.el6.x86_64 on an x86_64

login: 

执行成功了！！！