scanner.py

#coding=utf-8

import socket

import os
import struct
from ctypes import *

import threading
import time
from netaddr import IPNetwork,IPAddress


# 监听的主机
host = "192.168.0.105"

# 扫描的目标子网
subnet = "192.168.0.0/24"

# 自定义的字符串，我们将在ICMP响应中进行核对
magic_message = "PYTHONRULES!"

# 批量发送UDP数据包
def udp_sender(subnet, magic_message):
    time.sleep(5)
    sender = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    
    for ip in IPNetwork(subnet):
        
        try:
            sender.sendto(magic_message, ("%s" % ip, 65212))
        except:
            pass
        

# IP头定义
class IP(Structure):
    _fields_ = [
        ("ihl",          c_ubyte, 4),
        ("version",      c_ubyte, 4),
        ("tos",          c_ubyte),
        ("len",          c_ushort),
        ("id",           c_ushort),
        ("offset",       c_ushort),
        ("ttl",          c_ubyte),
        ("protocol_num", c_ubyte),
        ("sum",          c_ushort),
        ("src",          c_ulong),
        ("dst",          c_ulong)
    ]
    
    def __new__(self, socket_buffer=None):
        return self.from_buffer_copy(socket_buffer)
    
    def __init__(self, socket_buffer=None):
        
        # 协议字段与协议名称对应
        self.protocol_map = {1:"ICMP", 6:"TCP", 17:"UDP"}
        
        # 可读性更强的IP地址
        self.src_address = socket.inet_ntoa(struct.pack("<L", self.src))
        self.dst_address = socket.inet_ntoa(struct.pack("<L", self.dst))
        
        # 协议类型
        try:
            self.protocol = self.protocol_map[self.protocol_num]
        except:
            self.protocol = str(self.protocol_num)


# ICMP头定义
class ICMP(Structure):
    
    _fields_ = [
        ("type",         c_ubyte),
        ("code",         c_ubyte),
        ("checksum",     c_ushort),
        ("unused",       c_ushort),
        ("next_hop_mtu", c_ushort)
    ]
    
    def __new__(self, socket_buffer):
        return self.from_buffer_copy(socket_buffer)
    
    def __init__(self, socket_buffer):
        pass
    


# 下面的代码类似于之前的例子
if os.name == "nt":
    socket_protocol = socket.IPPROTO_IP
else:
    socket_protocol = socket.IPPROTO_ICMP

sniffer = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket_protocol)

sniffer.bind((host,0))
sniffer.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)

if os.name == "nt":
    sniffer.ioctl(socket.SIO_RCVALL, socket.RCVALL_ON)


t = threading.Thread(target=udp_sender,args=(subnet, magic_message))
t.start()


try:
    
    while True:
        
        # 读取数据包
        raw_buffer = sniffer.recvfrom(65565)[0]
        
        # 将缓冲区的前20个字节按IP头进行解析
        ip_header = IP(raw_buffer[0:20])
        
        # 输出协议和通信双方IP地址
        # print "Protocol: %s %s -> %s" % (ip_header.protocol, ip_header.src_address, ip_header.dst_address)
        
        # 如果为ICMP，进行处理
        if ip_header.protocol == "ICMP":
            
            # 计算ICMP包的起始位置
            offset = ip_header.ihl * 4
            buf = raw_buffer[offset:offset + sizeof(ICMP)]
            
            # 解析ICMP数据
            icmp_header = ICMP(buf)
            
            # print "ICMP -> Type: %d Code: %d" % (icmp_header.type, icmp_header.code)
            
            # 检查类型和代码值是否为3
            if icmp_header.code == 3 and icmp_header.type == 3:
                
                # 确认相应的主机在我们的目标子网内
                if IPAddress(ip_header.src_address) in IPNetwork(subnet):
                    
                    # 确认ICMP数据中包含我们发送的自定义字符串
                    if raw_buffer[len(raw_buffer)-len(magic_message):] == magic_message:
                        print "Host Up: %s" % ip_header.src_address
                
        
# 处理CTRL-C
except KeyboardInterrupt:
    
    # 如果运行在Windows上，关闭混杂模式
    if os.name == "nt":
        sniffer.ioctl(socket.SIO_RCVALL, socket.RCVALL_OFF)