[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！！！
转自：http://blog.sina.com.cn/s/blog_5022501501010pin.html