使用 Scapy 从 pcap 中选择数据包

Question

I'm tryng to get ciphersuites from pcap file with Scapy. I would like to get only the first packet from every file, beacause I'm using a filter.

This is my code:

from scapy.all import *
from scapy.layers.radius import Radius
import re
import os
import pathlib

    

def get_ciphersuite():
    ciphersuites = {
        #'0000' : 'TLS_NULL_WITH_NULL_NULL',
        '002f' : 'TLS_RSA_WITH_AES_128_CBC_SHA',
        '0035' : 'TLS_RSA_WITH_AES_256_CBC_SHA',
        '003c' : 'TLS_RSA_WITH_AES_128_CBC_SHA256',
        '003d' : 'TLS_RSA_WITH_AES_256_CBC_SHA256',
        '009c' : 'TLS_RSA_WITH_AES_128_GCM_SHA256',
        '009d' : 'TLS_RSA_WITH_AES_256_GCM_SHA384',
        'c02c' : 'TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384'
    }
    dir_pcaps = "./pcaps/"
    pcaps = os.listdir(dir_pcaps)
    for pcap in pcaps:
        if pathlib.Path(pcap).suffix in [".pcap", ".cap", ".pcapng"]:
            packets = rdpcap(dir_pcaps+pcap)
            print(packets)
            for packet in packets:
                if packet.haslayer("Radius") and packet[IP].src == "10.10.10.40":
                    rp = packet.getlayer("Radius")
                    rp_hex = bytes_hex(rp).decode()
                    for ciphersuite in ciphersuites:
                        r = re.findall(ciphersuite, rp_hex)
                        if r:
                            print(ciphersuites[ciphersuite]," --> "+pcap)
                            
                            break
                        else:
                            pass
                        
get_ciphersuite()

This is the output:

<128CBCSHA.pcapng: TCP:0 UDP:20 ICMP:0 Other:1>
TLS_RSA_WITH_AES_128_CBC_SHA  --> 128CBCSHA.pcapng
TLS_RSA_WITH_AES_128_CBC_SHA256  --> 128CBCSHA.pcapng
TLS_RSA_WITH_AES_128_CBC_SHA256  --> 128CBCSHA.pcapng
TLS_RSA_WITH_AES_128_CBC_SHA256  --> 128CBCSHA.pcapng
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384  --> 128CBCSHA.pcapng
<test.pcapng: TCP:0 UDP:11 ICMP:0 Other:1>
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384  --> test.pcapng
TLS_RSA_WITH_AES_256_CBC_SHA256  --> test.pcapng

This script returns me the ciphersuite for every packet in every pcap file, but I need only the first packet in every file.

Answer 1

You could try using sniff . For instance, replace

packets = rdpcap(dir_pcaps+pcap)

with

packets = sniff(offline=dir_pcaps+pcap, count=1,
                lfilter=lambda x: x.haslayer("Radius") and x[IP].src == "10.10.10.40")