直接上程式碼：

<pre name="code" class="python"># _*_ coding: utf-8 _*_
__author__ = 'Hondsam Xu <[email protected]>'
import socket,struct

'''
 轉換為子網地址,並檢驗和輸出正確的子網地址
 192.168.2.1 -> 192.168.2.1/255.255.255.255
 192.168.2.1/24 -> 192.168.2.0/255.255.255.0
 192.168.2.1/255.255.255.0 -> 192.168.2.0/255.255.255.0
 '''
def format_subnet(subnet_input):
    # 如果輸入的ip，將掩碼加上後輸出
    if subnet_input.find("/") == -1:
        return subnet_input + "/255.255.255.255"

    else:
        # 如果輸入的是短掩碼，則轉換為長掩碼
        subnet = subnet_input.split("/")
        if len(subnet[1]) < 3:
            mask_num = int(subnet[1])
            last_mask_num = mask_num % 8
            last_mask_str = ""
            for i in range(last_mask_num):
                last_mask_str += "1"
            if len(last_mask_str) < 8:
                for i in range(8-len(last_mask_str)):
                    last_mask_str += "0"
            last_mask_str = str(int(last_mask_str,2))
            if mask_num / 8 == 0:
                subnet = subnet[0] + "/" + last_mask_str +"0.0.0"
            elif mask_num / 8 == 1:
                subnet = subnet[0] + "/255." + last_mask_str +".0.0"
            elif mask_num / 8 == 2 :
                subnet = subnet[0] + "/255.255." + last_mask_str +".0"
            elif mask_num / 8 == 3:
                subnet = subnet[0] + "/255.255.255." + last_mask_str
            elif mask_num / 8 == 4:
                subnet = subnet[0] + "/255.255.255.255"
            subnet_input = subnet

        # 計算出正確的子網地址並輸出
        subnet_array = subnet_input.split("/")
        subnet_true = socket.inet_ntoa(\
            struct.pack("!I",struct.unpack("!I",socket.inet_aton(subnet_array[0]))[0] & \
            struct.unpack("!I",socket.inet_aton(subnet_array[1]))[0]))\
            + "/" + subnet_array[1]
        return subnet_true


# 判斷ip是否屬於某個網段
def ip_in_subnet(ip,subnet):
    subnet = format_subnet(str(subnet))
    subnet_array = subnet.split("/")
    ip = format_subnet(ip + "/" + subnet_array[1])
    return ip == subnet

print (ip_in_subnet("192.168.2.252","192.168.0.0/255.255.0.0"))
print (ip_in_subnet("192.168.2.252","192.168.3.0/255.255.255.0"))
print (ip_in_subnet("192.168.2.252","192.168.2.0/23"))
print (ip_in_subnet("192.168.2.252","192.168.2.0/29"))
print (ip_in_subnet("192.168.2.2","192.168.2.2"))
print (ip_in_subnet("192.168.2.2","192.168.2.3"))