检查服务是否可达并使用 Python 中的套接字模块

Question

The context related to my question is that I work for a company in the networking area. This company has several stores around the country where DVRs are accessible through port 2781 and a domain for people to access security cameras, the problem is that in order for these people to successfully access DVRs through the domain and port you must have a DMZ configured in the modem of the stores. To corroborate the DMZ I'm trying to use Python with the sockets module but I don't understand the best way to do it yet.

import socket
    
s = socket.socket()
s.connect((domain, port))
s.close()

Once I make the proper connection which is the best way to check if there is a communication? Work it with an exception or just use socket.recv and detect if it is empty?

Answer 1

In order for connect to succeed there already has to be some kind of connection be done. Otherwise the TCP handshake would fail. Thus the first step would be to check if connect succeeds or throws an exception.

It can still be possible that there is some deep packet inspection firewall in place which does not block the initial connection but only blocks the later data exchange. To find out if this is the case you have to do actual bidirectional communication. But how this communication should look like depends on the specific application protocol which is unknown in your case. Still you need to check that a) sending and receiving works (catching exceptions) and b) that a response returns the expected data.