Argparse '参数 1 必须是 str、bytes 或字节数组，而不是 None'

Question

import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
import sys
from scapy.all import *
import argparse
parser = argparse.ArgumentParser(add_help=False)
parser.add_argument("--remote_host")
parser.add_argument("--verbose")
parser.add_argument("--help", action='store_true')
args = parser.parse_args()

if args.help:
print("HELP...")
# Define end host and TCP port range
hostInput    = args.remote_host
host  = socket.gethostbyname(hostInput)
port_range = [21,22,23,25,53,80,110,135,137,138,139,443,1433,1434,8080]
# Send SYN with random Src Port for each Dst port
for dst_port in port_range:
src_port = random.randint(1025,65534)
resp = sr1(
IP(dst=host)/TCP(sport=src_port,dport=dst_port,flags="S"),timeout=1,
verbose=int(args.verbose),
)
if resp is None:
print(f"{host}:{dst_port} is filtered (silently dropped).")
elif(resp.haslayer(TCP)):
if(resp.getlayer(TCP).flags == 0x12):
# Send a gratuitous RST to close the connection
send_rst = sr(
IP(dst=host)/TCP(sport=src_port,dport=dst_port,flags='R'),
timeout=1,
verbose=int(args.verbose),
)
print(f"{host}:{dst_port} is open.")
elif (resp.getlayer(TCP).flags == 0x14):
print(f"{host}:{dst_port} is closed.")
elif(resp.haslayer(ICMP)):
if(
int(resp.getlayer(ICMP).type) == 3 and
int(resp.getlayer(ICMP).code) in [1,2,3,9,10,13]
):
print(f"{host}:{dst_port} is filtered (silently dropped).")

使用--remote_host 127.0.0.1 --verbose 1运行正常，无错误

使用--help运行生成：

TypeError: gethostbyname() argument 1 must be str, bytes or bytearray, not None

注：当然，只有当我包括print("Help...")以下的所有行时，才会出现上述错误

以下是完整的回溯：

Python 3.8.0 (tags/v3.8.0:fa919fd, Oct 14 2019, 19:37:50) [MSC v.1916 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license()" for more information.
>>> 
= RESTART: C:Users0082563AppDataLocalProgramsPythonAT2_PythonNetworkApplications.v1.1aScenario 1logger.py
HELP...
Traceback (most recent call last):
File "C:Users0082563AppDataLocalProgramsPythonAT2_PythonNetworkApplications.v1.1aScenario 1logger.py", line 48, in <module>
host  = socket.gethostbyname(hostInput)
TypeError: gethostbyname() argument 1 must be str, bytes or bytearray, not None
>>>

Answer 1

正如上面评论中所建议的，我需要在之后退出程序

if args.help:
print("HELP...")

因此，在下面的脚本中，用户可以在CLI中添加--remote_host google.com --verbose 0(或verbose 1表示完整的verbose…(

用户可以在CLI中使用--help来打印自定义帮助部分，之后程序将退出。

#!/usr/bin/env python

import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
import sys
from scapy.all import *
import argparse
parser = argparse.ArgumentParser(add_help=False)
parser.add_argument("--remote_host")
parser.add_argument("--verbose")
parser.add_argument("--help", action='store_true')
args = parser.parse_args()

if args.help:
print("Help section...")
exit()

# Define end host and TCP port range
hostInput    = args.remote_host
host  = socket.gethostbyname(hostInput)
port_range = [21,22,23,25,53,80,110,135,137,138,139,443,1433,1434,8080]
# Send SYN with random Src Port for each Dst port
for dst_port in port_range:
src_port = random.randint(1025,65534)
resp = sr1(
IP(dst=host)/TCP(sport=src_port,dport=dst_port,flags="S"),timeout=1,
verbose=int(args.verbose),
)
if resp is None:
print(f"{host}:{dst_port} is filtered (silently dropped).")
elif(resp.haslayer(TCP)):
if(resp.getlayer(TCP).flags == 0x12):
# Send a gratuitous RST to close the connection
send_rst = sr(
IP(dst=host)/TCP(sport=src_port,dport=dst_port,flags='R'),
timeout=1,
verbose=int(args.verbose),
)
print(f"{host}:{dst_port} is open.")
elif (resp.getlayer(TCP).flags == 0x14):
print(f"{host}:{dst_port} is closed.")
elif(resp.haslayer(ICMP)):
if(
int(resp.getlayer(ICMP).type) == 3 and
int(resp.getlayer(ICMP).code) in [1,2,3,9,10,13]
):
print(f"{host}:{dst_port} is filtered (silently dropped).")