I tried to communicate with a remote server by Socket communication with Python.

Purpose

--Exchange data with a remote VPS server in Python

There are many insecure parts due to the nature of what we are doing, so it is for testing and hobbies only.

environment

• CentOS 7.8.2003
• PHP 7.3
• Python 3.7 --Sakura's VPS (* 10th Anniversary Congratulations!)

Server side

Prepare the server. In my example, I borrowed Sakura's VPS.

Environment

(Note) Precautions when using Sakura's VPS

Add packet filtering settings from the control panel. You can turn it off, but it is not recommended as it is not good for security.

In this example, I wanted to use the port number of 50000, so I turned it off temporarily.

Port settings

Set as necessary. This example is Sakura's VPS setting example. Also, change the port number to your liking.

$ firewall-cmd --zone=public --add-port=50000/tcp --permanent

Don't forget to reflect the settings!

$ firewall-cmd --reload

install php

In this example, php7.3 is installed.

remi

$ yum -y install http://rpms.famillecollet.com/enterprise/remi-release-7.rpm

There are a lot of extra things in it, but please change them as needed.

$ yum -y install --enablerepo=remi,remi-php73 php php-mbstring php-xml php-xmlrpc php-gd php-pdo php-pecl-mcrypt php-mysqlnd php-pecl-mysql

Build a socket server using PHP-WebSocket

In this example, the external library PHP-WebSocket is used.

Drop Binaries here into your Apache directory.

$ cd /var/www/html
$ wget https://github.com/nicokaiser/php-websocket/archive/php-websocket.zip
$ unzip php-websocket.zip
$ sudo rm -rf php-websocket.zip

After downloading, edit server.php in php-websocket / server. If vim is not installed, use vi or install it with yum -y install vim.

$ cd php-websocket/server
$ vim server.php

Change and save '<global IPv4 address>' and 50000 (port) as appropriate.

<?php

error_reporting(0);

require(__DIR__ . '/lib/SplClassLoader.php');

$classLoader = new SplClassLoader('WebSocket', __DIR__ . '/lib');
$classLoader->register();

$server = new \WebSocket\Server('<Global IPv4 address>', 50000);
$server->registerApplication('echo', \WebSocket\Application\EchoApplication::getInstance());
$server->registerApplication('time', \WebSocket\Application\TimeApplication::getInstance());
$server->run();

Then rewrite the handshake function in php-websocket / lib / WebSocket / Connection.php. Rewrite the handshake function on the 28 line as follows.

private function handshake($data)
{
    socket_write($this->socket, $data, strlen($data));
    $this->application->onConnect($this);
    return true;
}

Start WebSocket server

Start with the following command.

$ php server.php

When this happens, the server startup is complete. Move on to the client.

[root@~]# php server.php 
2020-09-14 14:02:13 [info] Server created

Client side (Python)

Client-side code that sends data.

--Replace '<global IPv4 address>' -- 50000 is the port

import socket

if __name__ == '__main__':
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
        sock.connect(('<Global IPv4 address>', 50000))
        data = 'Hello From Python Client!'
        sock.send(data.encode())
        print(sock.recv(1024).decode())

Try to hit

If the transmitted data is echoed, it is successful. It's a bit of a push, but I was able to do it for the time being.

[root@myserver]# php server.php 
2020-09-14 15:00:53 [info] Server created
2020-09-14 15:00:55 [info] [client XXX] Connected

in conclusion

It was unexpectedly troublesome. .. Thank you for visiting.