Question

我想绑定一个套接字来侦听某个范围内的任何开放端口。通常我绑定到零，操作系统很好地给我一个随机的开放端口。但是现在我需要保持在防火墙指定的4000-5000之间的某个范围内。如何向操作系统询问此范围内的开放端口？

我是用Python做的。我对跨平台解决方案很感兴趣，但我会选择特定于Linux的解决方案。

Answer 1

你需要写一个函数来做到这一点。像这样的东西。

它只是在给定的范围内随机选择一个端口并尝试绑定它。如果已经采用，则引发套接字错误98。然后循环并选择另一个直到成功，或者在10次尝试后仍然不成功退出以防止死锁。主程序调用此函数并侦听套接字。如果需要，可以使用getsockname来显示端口。

import socket
import random

def bind_to_random_socket(low, up):
    _counter = 0
    foo = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    while True:
        try:
            _port = random.randint(low, up)
            foo.bind(("localhost", _port))
            return foo
        except:
            counter += 1

        if counter > 10:
            print "cannot find a free port within range"
            exit(1)


_ns = bind_to_random_socket(4000, 4200)
# to get the port number:
_addr, _port = _ns.getsockname()
print _port

_ns.listen(1)

希望这会有所帮助。

哈努哈利

Answer 2

为了完全相同的目的，我写了一小段代码

# SWAMI KARUPPASWAMI THUNNAI
import socket

class Ports:
    """
    This class is ued to find all the open ports present
    """
    __upper_bound = 0
    __lower_bound = 0
    __ip = "127.0.0.1" # change your i.p if it is not your machine IP
    __ports = [] # our actively available ports
    # used to set upper and lower bounds i.e the range of the ports to be scanned
    def __init__(self,initial,final):
        self.__lower_bound=initial
        self.__upper_bound=final

    # a method which scans for the range of ports
    def scan_for_ports(self):
        for i in range(self.__lower_bound,self.__upper_bound):
            print("[SCANNING]: "+str(i))
            check = self.is_port_opened(i)
            if check == 0:
                self.__ports.append(i) # append our opened port no
    # a method to find whether a port is opened
    def is_port_opened(self,portNo):
        try:
            client = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
            connection = client.connect_ex((self.__ip,portNo)) # remember it is a tuple
            port_opened = connection
            client.close()
            print(port_opened)
            return port_opened
        except socket.error as e:
            print("SOCKET CANNOT BE CREATED! Do you have admin previlidges? or the port may be closed!")
            print(e)
            return -1
        return -1
    # A method to get the list of open ports
    def get_list(self):
        for i in self.__ports:
            print("OPENED: "+str(i))


if __name__=="__main__":
    ports = Ports(75,81)
    ports.scan_for_ports()
    ports.get_list()

现在，您可以轻松编写客户端以侦听特定端口。我已经在我的计算机上打开了一个端口（80），使用一个小的python脚本进行几分钟测试，结果很好看到这里！

绑定在特定范围内打开端口

2 个答案: