如何确定给定的IP地址是官方Internet地址还是内部Intranet IP地址?
Intranet IP通常位于私有IP范围内:
10.0.0.0 through 10.255.255.255 172.16.0.0 through 172.31.255.255 192.168.0.0 through 192.168.255.255
这些不适用于Internet IP地址.
另见http://compnetworking.about.com/od/workingwithipaddresses/f/privateipaddr.htm