作業系統：kail32位

第二章：網路程式設計

   tcp（傳輸控制協議）：面向連線，通訊時創造一條連線，提供順序的可靠地，不重複的資料傳輸，不會被加上資料邊界，每個傳送的訊息，可能會拆成很多份，每一份會不多不少的到達目的地，然後按照一定的順序拼接起來，傳給正在等待的應用程式

  UDP：無連線，資料是整個傳送，具有資料邊界，資料到達的順序、可靠性及不重複性無法保證

建立一個netcat工具：

  1）匯入模組，定義全域性變數，

subprocess：提供強大的程序建立藉口，可以提供多種與客戶端互動的方法

#!/usr/bin/env python2
# -*- coding: utf-8 -*-
"""
Created on Sun Jul  2 04:24:51 2017

@author: root
"""

import sys
import socket
import getopt
import threading
import subprocess

# define the global arg
listen  = False
command = False
upload = False
execute = ""
target = ""
upload_destination = ""
port = 0


def usage():
    print "BHP Net Tool"
    print 
    print "Usage:bhpnet.py -t target_host -p port"
    print "-l --listen     -listen on [host]:[port] for incoming connect"
    print "-e --execute = file_to_run -execute the given file upon receiving a connection"
    print "-c --command   -- initialize a commend shell"
    print  "-u --upload = destination -upon receiving connecction upload file and write to [destination]"
    print
    print
    print "examples:"
    print "bhpnet.py -t 192.168.0.1 -p 5555 -l -c"
    print "bhpnet.py -t 192.168.0.1 -p 5555 -l -u=c:\\target.exe"
    print "bhpnet.py -t 192.168.0.1 -p 5555 -l -e=\"cat /etc/passwd\""
    print "echo 'ABCDEFG' | ./bhpnet.py -t 192.168.11.12 -p 135"
    sys.exit(0)
    
def main():
    global listen
    global port
    global execute
    global command
    global upload_destination
    global target
    
    if not len(sys.argv[1:]):
        usage()
    try:
        opts,args = getopt.getopt(sys.argv[1:],"hle:t:p:cu:",["help","listen","execute","target","port","command","upload"])
        print opts
    except getopt.GetoptError as err:
        print str(err)
        usage()
    for o,a in opts:
        if o in ("-h","help"):
            usage()
        elif o in("-l","--listen"):
            listen = True
        elif o in("-e","--execute"):
            execute = a
        elif o in ("-c","--commadnshell"):
            command = True
        elif o in ("-u","--upload"):
            upload_destination = a
        elif o in ("-t","--target"):
            target = a
        elif o in("-p","--port"):
            port = int(a)
        else:
            assert False,"unhandled option"
        
    def client_sender(buffer):
        client = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        
        try: 
            client.connect((target,port))
            if len(buffer):
                client.send(buffer)
                
            while True:
                recv_len = 1
                response = ""
                while recv_len:
                    data =client.recv(4096)
                    recv_len = len(data)
                    response += data
                    
                    if recv_len <4096:
                        break
                print response,
                buffer = raw_input("")
                buffer += "\n"
                
                client.send(buffer)
        except:
            print "[*] Exception exiting."
            client.close()
        
    def server_loop():
        global target
        
        if not len(target):
            target = "0.0.0.0"
            
        server = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        server.bind((target,port))
        
        server.listen(5)
        while True:
            client_socket,addr = server.accept()
            
            client_thread = threading.Thread(target=client_handler,args=(client_socket,))
            client_thread.start()
    def run_command(command):
        
        command = command.rstrip()
        try:
            output = subprocess.check_output(command,stderr=subprocess.STDOUT,shell=True)
        except:
            output = "faile to exectue command \r\n"
            
        return output
    
    def client_handler(client_socket):
        global upload
        global execute
        global command
        
        if len(upload_destination):
            file_buffer = ""
            while True:
                data = client_socket.recv(1024)
                if not data:
                    break
                else:
                    file_buffer += data
            try:
                file_descriptor = open(upload_destination,"w")
                file_descriptor.write(file_buffer)
                file_descriptor.close()
                
                client_socket.send("successfully saved file %s\r\n"%upload_destination)
            except:
                client_socket.send("Failed to save file to %s\r\n"%upload_destination)
        if len(execute):
            output = run_command(execute)
            client_socket.send(output)
            
        if command:
            while True:
                client_socket.send("<BHP:#>")
                cmd_buffer = ""
                while "\n" not in cmd_buffer:
                    cmd_buffer += client_socket.recv(1024)
                response = run_command(cmd_buffer)
                client_socket.send(response)
                
    if not listen and len(target) and port >0:
        buffer = sys.stdin.read()
        client_sender(buffer)
    
    if listen:
        server_loop()
main()