Linux [Errno 13]权限被拒绝

Question

我有一个在Windows上工作的python脚本，但是在上运行它很困难。这里没有太多的智慧

test.py

#!/usr/bin/env python3

"""
https://pymodbustcp.readthedocs.io/en/latest/examples/server_allow.html

An example of Modbus/TCP server which allow modbus read and/or write only from
specific IPs.

Run this as root to listen on TCP privileged ports (<= 1024).
"""

import argparse
from pyModbusTCP.server import ModbusServer, DataHandler
from pyModbusTCP.constants import EXP_ILLEGAL_FUNCTION


# some const
ALLOW_R_L = ['127.0.0.1', '192.168.0.104']
ALLOW_W_L = ['127.0.0.1']


# a custom data handler with IPs filter
class MyDataHandler(DataHandler):
    def read_coils(self, address, count, srv_info):
        if srv_info.client.address in ALLOW_R_L:
            return super().read_coils(address, count, srv_info)
        else:
            return DataHandler.Return(exp_code=EXP_ILLEGAL_FUNCTION)

    def read_d_inputs(self, address, count, srv_info):
        if srv_info.client.address in ALLOW_R_L:
            return super().read_d_inputs(address, count, srv_info)
        else:
            return DataHandler.Return(exp_code=EXP_ILLEGAL_FUNCTION)

    def read_h_regs(self, address, count, srv_info):
        if srv_info.client.address in ALLOW_R_L:
            return super().read_h_regs(address, count, srv_info)
        else:
            return DataHandler.Return(exp_code=EXP_ILLEGAL_FUNCTION)

    def read_i_regs(self, address, count, srv_info):
        if srv_info.client.address in ALLOW_R_L:
            return super().read_i_regs(address, count, srv_info)
        else:
            return DataHandler.Return(exp_code=EXP_ILLEGAL_FUNCTION)

    def write_coils(self, address, bits_l, srv_info):
        if srv_info.client.address in ALLOW_W_L:
            return super().write_coils(address, bits_l, srv_info)
        else:
            return DataHandler.Return(exp_code=EXP_ILLEGAL_FUNCTION)

    def write_h_regs(self, address, words_l, srv_info):
        if srv_info.client.address in ALLOW_W_L:
            return super().write_h_regs(address, words_l, srv_info)
        else:
            return DataHandler.Return(exp_code=EXP_ILLEGAL_FUNCTION)


if __name__ == '__main__':
    # parse args
    parser = argparse.ArgumentParser()
    parser.add_argument('-H', '--host', type=str, default='localhost', help='Host (default: localhost)')
    parser.add_argument('-p', '--port', type=int, default=502, help='TCP port (default: 502)')
    args = parser.parse_args()
    # init modbus server and start it
    server = ModbusServer(host=args.host, port=args.port, data_hdl=MyDataHandler())
    server.start()

当我从SSH运行这个程序时，我得到：

Traceback (most recent call last):
  File "/home/ben/anaconda3/lib/python3.7/site-packages/pyModbusTCP/server.py", line 989, in start
    self._service.server_bind()
  File "/home/ben/anaconda3/lib/python3.7/socketserver.py", line 466, in server_bind
    self.socket.bind(self.server_address)
PermissionError: [Errno 13] Permission denied

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "test.py", line 69, in <module>
    server.start()
  File "/home/ben/anaconda3/lib/python3.7/site-packages/pyModbusTCP/server.py", line 992, in start
    raise ModbusServer.NetworkError(e)
pyModbusTCP.server.NetworkError: [Errno 13] Permission denied

如果我在目录上执行一个ls -la：

total 12
drwxrwxr-x 2 ben ben 4096 Aug  7 10:57 .
drwxr-xr-x 5 ben ben 4096 Aug  7 10:50 ..
-rw-rw-r-- 1 ben ben 2522 Aug  7 10:54 test.py

Answer 1

在基于Unix的环境中(Linux等)1024及以下的TCP端口被视为特权。这是有历史原因的，因为内部服务运行在低端口上(即端口22上的sshd )。

有两种方法可以解决这个问题：

1. 作为根用户运行，允许您从bind到端口502 (这似乎是默认的)。
2. 使用-p或--port命令行选项运行，以指定端口为1025或更多。这些端口不需要根特权。

Answer 2

您与哪个用户一起运行脚本？

为了不将用户更改为root用户，可以在命令开始时输入sudo来测试运行脚本。例如：

sudo python3 script.py