python对ip地址的子网掩码各种转换处理

1.反掩码（0.0.0.1）转换成（255.255.255.254）

a = "255.255.255.255"
b = "0.0.0.1"
d = []
for i in range(4):
    d.append(int(a.split(".")[i])-int(b.split(".")[i]))
print str(d).replace("[","").replace(",",".").replace("]","").replace(" ","")