Polar Proxy

A proxy server is a kind of "mediator" between your equipment and a remote server (or the whole Internet). It can be used, for example, to swap your real IP address for another one, to bypass blocking. Proxies can also be actively used to intercept traffic (e.g. when testing created web applications).

To keep only unique external links while scraping with Scrapy, you can use a set to track the visited external links and filter out duplicates. Here's an example spider that demonstrates how to achieve this:

import scrapy
from urllib.parse import urlparse, urljoin

class UniqueLinksSpider(scrapy.Spider):
    name = 'unique_links'
    start_urls = ['http://example.com']  # Replace with the starting URL of your choice
    visited_external_links = set()

    def parse(self, response):
        # Extract all links from the current page
        all_links = response.css('a::attr(href)').extract()

        for link in all_links:
            full_url = urljoin(response.url, link)

            # Check if the link is external
            if urlparse(full_url).netloc != urlparse(response.url).netloc:
                # Check if it's a unique external link
                if full_url not in self.visited_external_links:
                    # Add the link to the set of visited external links
                    self.visited_external_links.add(full_url)

                    # Yield the link or process it further
                    yield {
                        'external_link': full_url
                    }

        # Follow links to other pages
        for next_page_url in response.css('a::attr(href)').extract():
            yield scrapy.Request(url=urljoin(response.url, next_page_url), callback=self.parse)

- visited_external_links is a class variable that keeps track of the unique external links across all instances of the spider.
- The parse method extracts all links from the current page.
- For each link, it checks if it is an external link by comparing the netloc (domain) of the current page and the link.
- If the link is external, it checks if it is unique by looking at the visited_external_links set.
- If the link is unique, it is added to the set, and the spider yields the link or processes it further.
- The spider then follows links to other pages, recursively calling the parse method.

Remember to replace the start_urls with the URL from which you want to start scraping.

Technically, the ISP cannot block all VPN servers. But it is possible to block some of them. In this case, you can use any other VPN service. But you have to be careful with "free" ones, as they often make money from collecting and selling users' confidential data.

A VPN on your phone lets you protect your privacy when you connect to public WiFi hotspots. You can also use it to hide your real location, connect to blocked sites and applications. There are many ways to use VPN.

Common users can use proxies to bypass blocking, to protect their personal data and to hide their real IP address or data about the equipment they use. But network administrators use them to analyze network traffic and test web applications.