找出指定网络内能连通外网的ip

#/*************************************************************************                                                                                                                  
#    > File Name: scannet.sh
#    > Author: liyong
#    > Mail: 2550702985@qq.com
#    > Created Time: 2017-05-10 11:08
#    > Last modified: 2017-05-10 11:08
read -p " please input your network(eg:172.16.252.166)" net 

#取ip段 设置ip
net=` echo $net|cut -d"."