to print the limited number of packet using pyshark

Question

I want to capture the limited number of packet. for example, while I am using the command python python.py -I eth0 -c 10 then I wan to capture only 10 number of packet and exit but I am getting error.the below are the code and erro I am getting.

!/usr/bin/python

import argparse
import pyshark
import time
import re as regex


parser = argparse.ArgumentParser()
parser.add_argument('-i', '--interface', metavar=" ", type=str, required = True, help = 'To specify the interface ')
parser.add_argument('-v', '--verbose', required = False, action = 'store_true', help = 'To print the all layer of packet')
parser.add_argument('-o', '--output', metavar=' ', help = 'To capture and save the pcap in a file')
parser.add_argument('-p', '--protocol', metavar=' ', help= 'To capture packet using ptotocl filter')
parser.add_argument('-u', '--udp', action = 'store_true', help = 'To capture udp packet only')
parser.add_argument('-t', '--tcp', action = 'store_true', help = 'To capture tcp packet only')
parser.add_argument('-c', '--count', metavar=' ',default=1,  help = 'To capture limited number of packet')

args = parser.parse_args()

if args.protocol:
   capture = pyshark.LiveCapture(interface=args.interface, display_filter=args.protocol)


elif args.udp:
   capture = pyshark.LiveCapture(interface=args.interface, bpf_filter='udp')

elif args.tcp:
   capture = pyshark.LiveCapture(interface=args.interface, bpf_filter='tcp')

else:
   capture = pyshark.LiveCapture(interface=args.interface, output_file=args.output)
   capture.sniff(packet_count = args.count)

packet_list = []

for packet in capture.sniff_continuously():
    if 'IP Layer' in str(packet.layers):
        protocol = regex.search(r'(Protocol:)(.*)',str(packet.ip))
        protocol_type = protocol.group(2).strip().split(' ')[0]
       # proto = protocol_type
    localtime = time.asctime(time.localtime(time.time())) 
    proto = protocol_type
    src_addr = packet.ip.src
    dst_addr = packet.ip.dst
    length = packet.length
    print (localtime, '\t' , proto, '\t' ,src_addr, '\t', dst_addr, '\t' , length)
    if args.verbose:
       print(packet.show())

error

python python.py -i eth0 -c 10  

Traceback (most recent call last):
  File "/home/kali/python.py", line 32, in <module>
    capture.sniff(packet_count = args.count)
  File "/home/kali/.local/lib/python3.10/site-packages/pyshark/capture/capture.py", line 144, in load_packets
    self.apply_on_packets(
  File "/home/kali/.local/lib/python3.10/site-packages/pyshark/capture/capture.py", line 256, in apply_on_packets
    return self.eventloop.run_until_complete(coro)
  File "/usr/lib/python3.10/asyncio/base_events.py", line 646, in run_until_complete
    return future.result()
  File "/home/kali/.local/lib/python3.10/site-packages/pyshark/capture/capture.py", line 267, in packets_from_tshark
    await self._go_through_packets_from_fd(tshark_process.stdout, packet_callback, packet_count=packet_count)
  File "/home/kali/.local/lib/python3.10/site-packages/pyshark/capture/capture.py", line 299, in _go_through_packets_from_fd
    if packet_count and packets_captured >= packet_count:
TypeError: '>=' not supported between instances of 'int' and 'str'

score 0 · Answer 1 · answered Feb 04 '23 at 07:04

  File "/home/kali/.local/lib/python3.10/site-packages/pyshark/capture/capture.py", line 299, in _go_through_packets_from_fd
    if packet_count and packets_captured >= packet_count:
TypeError: '>=' not supported between instances of 'int' and 'str'

It is expected that packet_count is an integer. But packet count is taken from the command line (args) and thus is as string unless explicitly given otherwise:

parser.add_argument('-c', '--count', metavar=' ',default=1,  help = 'To capture limited number of packet')
... 
    capture.sniff(packet_count = args.count)

To fix this args.count either must be converted to int explicitly or the proper type should be given when parsing the args with the type argument:

parser.add_argument('-c', '--count', type=int, metavar=' ', default=1,  help = 'To capture limited number of packet')

to print the limited number of packet using pyshark

1 Answers1