.常用子网掩码与位数对应表在ROS算号器里已经写了，不过为了方便，容易搜索，单独成文，方便查阅！记下规律，以后都不用在查了！128.0.0.0=1192.0.0.0=2224.0.0.0=3240.0.0.0=4248.0.0.0=5252.0.0.0=6254.0.0.0=7255.0.0.0=8255.128.0.0=9255.192.0.0=10255.224.0.0=11255.240.0.0=12255.248.0.0=13255.252.0.0=14255.254.0.0=15255.255.0.0=16255.255.128.0=17255.255.192.0=18255.255.224.0=19255.255.240.0=20255.255.248.0=21255.255.252.0=22255.255.254.0=23255.255.255.0=24255.255.255.128=25255.255.255.192=26255.255.255.2
