用wireshark抓包後要修改固定字段的值,代碼如下:
實作思路:
1. 用wireshark 打開pcap包,找到要修改的字段位置
2.用scapy讀取pcap包,取出指定位置的值,判斷是否為要替換的值,如果是替換新值後,把資料流拼接成新的一條完成資料流,放入新的資料包中,如果不符合的不修改直接放回,具體代碼如下:
一次修改單一IP的值
from tqdm import tqdm
from scapy.utils import PcapReader, PcapWriter
import socket
OLD_SOURCE_IP = '192.168.1.100'
OLD_DEST_IP = '192.168.2.100'
OLD_TEID = '0x0e60b0a4'
NEW_TEID = '0xd970575e'
NEW_SOURCE_IP = '172.16.1.100'
NEW_DEST_IP = '172.16.1.200'
i_filepath = "tpcu_200000.pcap" # pcap to read
o_filepath = "out_{0}".format(i_filepath) # pcap to write
i_open_file = PcapReader(i_filepath)
o_open_file = PcapWriter(o_filepath) # opened file to write
new_pkt = ''
for packet in tqdm(i_open_file):
byteArray = packet['Raw'].load
# format ip
source_ip = socket.inet_ntoa(byteArray[26:30])
des_ip = socket.inet_ntoa(byteArray[30:34])
if source_ip == OLD_SOURCE_IP and des_ip == OLD_DEST_IP:
# ip to bytes
new_source_ip = socket.inet_aton(NEW_SOURCE_IP)
new_dest_ip = socket.inet_aton(NEW_DEST_IP)
# hex to bytes
new_teid = bytes.fromhex(NEW_TEID.replace('0x',''))
new_pkt = byteArray[0:26] + new_source_ip + new_dest_ip + byteArray[34:46] + new_teid+byteArray[50:]
# write new pacp package
o_open_file.write(new_pkt)
elif source_ip == OLD_DEST_IP and des_ip == OLD_SOURCE_IP:
new_source_ip = socket.inet_aton(NEW_DEST_IP)
new_dest_ip = socket.inet_aton(NEW_SOURCE_IP)
new_teid = bytes.fromhex(NEW_TEID.replace('0x', ''))
new_pkt = byteArray[0:26] + new_source_ip + new_dest_ip + byteArray[34:46] + new_teid + byteArray[50:]
o_open_file.write(new_pkt)
else:
new_pkt = byteArray
o_open_file.write(new_pkt)
批量修改IP的值,dpkt 讀取pcap包的性能是scapy的10倍以上,批量操作時讀取用dpkt進行讀取,替換時間從12s優化到3s左右。
from tqdm import tqdm
from scapy.utils import PcapReader, PcapWriter
import socket
from config import *
from dpkt.pcap import Reader
'''
data = [{"source_ip":[old_source_ip,new_source_ip], "dest_ip":[old_dest_ip,new_dest_ip],"teid":[old_teid,new_teid]},
{"source_ip":[old_source_ip,new_source_ip], "dest_ip":[old_dest_ip,new_dest_ip],"teid":[old_teid,new_teid]}
]
'''
# pcap to write
o_filepath = "out_dpkt_{0}".format(i_filepath)
i_open_file = PcapReader(i_filepath)
# opened file to write
o_open_file = PcapWriter(o_filepath)
new_pkt = ''
flags = 0
def bytes_format_ip(byte):
return socket.inet_ntoa(byte)
def ip_format_bytes(ip):
return socket.inet_aton(ip)
def hex_format_bytes(hex_value):
return bytes.fromhex(hex_value.replace('0x',''))
with open(i_filepath,'rb') as f:
for _, byteArray in tqdm(Reader(f)):
flags = 0
source_ip = bytes_format_ip(byteArray[26:30])
des_ip = bytes_format_ip(byteArray[30:34])
teid = byteArray[46:50]
for i in data:
if teid == hex_format_bytes(i["teid"][0]) and source_ip == i["source_ip"][0] and des_ip == i["dest_ip"][0]:
new_source_ip = ip_format_bytes(i["source_ip"][-1])
new_dest_ip = ip_format_bytes(i["dest_ip"][-1])
new_teid = hex_format_bytes(i["teid"][-1])
new_pkt = byteArray[0:26] + new_source_ip + new_dest_ip + byteArray[34:46] + new_teid + byteArray[50:]
o_open_file.write(new_pkt)
flags = 1
break
# Unqualified direct return
if flags == 0:
o_open_file.write(byteArray)
# if __name__ == '__main__':
# update_ip_teid()