如何在Windows中使用Python生成TCP / UDP数据包？

Question

In Linux, I can generate a TCP/UDP packet with the following command.

echo "hello world" > /dev/tcp/127.0.0.1/1337
echo "hello world" > /dev/udp/127.0.0.1/31337

I've been searching a similar way to do it in Python, but it's not as simple as Linux.

1. https://wiki.python.org/moin/TcpCommunication

2. How To Generate Tcp,ip And Udp Packets In Python?

I'm using Python 3.5.1 in Windows and try the following code.

#!/usr/bin/env python

import socket

TCP_IP = '127.0.0.1'
TCP_PORT = 1337
BUFFER_SIZE = 1024
MESSAGE = "Hello, World!"

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((TCP_IP, TCP_PORT))
s.send(MESSAGE)
data = s.recv(BUFFER_SIZE)
s.close()

print ("received data:", data)

I've also performed a packet capture to see this packet and was able to see TCP 3 way handshake followed by FIN packet.

So, my questions are:

1. Why "Hello, World!" message did not appear in Wireshark (Follow TCP Stream)?

I can see the message when I run echo "hello world" > /dev/tcp/127.0.0.1/1337 in Linux.

2. I also get the following error when running the code.

I googled the error and found similar error here , but the code is different.

Please let me know what's wrong with the code and how to fix it.

C:\Python\Codes>tcp.py
Traceback (most recent call last):
  File "C:\Python\Codes\tcp.py", line 12, in <module>
    s.send(MESSAGE)
TypeError: a bytes-like object is required, not 'str'

C:\Python\Codes>

3. Is this the simplest way to generate TCP packet in Python?

Answer 1

Instead of this:

s.send(MESSAGE)

This:

b = s.send(MESSAGE.encode("utf8"))
s.send(b)

Answer 2

As the traceback says, it is a TypeError: a bytes-object like is required, not a str

so, you can use .encode() on a string to get a bytes-object like and then .decode() to get back the string.

MESSAGE = 'Hello, World!'
encoded = str.encode(MESSAGE)     # b'Hello, World!'
decoded = encoded.decode()        # 'Hello, World!' 

here, this link, you might find it useful. Best way to convert string to bytes in Python 3?

Hope it helps.