How do I avoid getting blocked while scraping with Simple HTML DOM?

Simple HTML DOM is a PHP library that provides an easy way to parse HTML documents and extract information from them. However, when scraping websites, it's common to encounter anti-scraping measures that can lead to your IP address being blocked. Here are some tips to avoid getting blocked while using Simple HTML DOM or any scraping tool:

1. Respect robots.txt: Before you start scraping a website, check its robots.txt file (usually found at http://www.example.com/robots.txt). This file tells search engines and other automated services which parts of the site should not be accessed. If the robots.txt disallows access to the parts you are interested in, you should respect that and avoid scraping those parts.

2. User-Agent: Change your HTTP request's User-Agent to mimic a real web browser. Websites often block requests with non-standard user agents (often associated with bots).

   $context = stream_context_create(array('http' => array('header' => 'User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3')));
   $html = file_get_html('http://www.example.com/', false, $context);
   

3. Rate Limiting: Do not send too many requests in a short time. Websites might block you for excessive access. Implement a delay between requests.

   foreach ($urls as $url) {
       $html = file_get_html($url);
       // Process the page...
   
       // Wait for 5 seconds before the next request
       sleep(5);
   }
   

4. Referer: Some websites check the Referer header to see if you navigated from within the site. You can set this header to make it look like you're browsing the site normally.

   $context = stream_context_create(array('http' => array('header' => "Referer: http://www.example.com/\r\n")));
   $html = file_get_html('http://www.example.com/page', false, $context);
   

5. Cookies and Sessions: Some websites require you to maintain a session. You can use curl in PHP to handle cookies.

   $ch = curl_init();
   curl_setopt($ch, CURLOPT_URL, 'http://www.example.com/');
   curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
   curl_setopt($ch, CURLOPT_HEADER, 1);
   curl_setopt($ch, CURLOPT_USERAGENT, 'Your User Agent');
   $result = curl_exec($ch);
   
   // Use regex or another method to extract cookies from the response headers
   // and use them in subsequent requests
   

6. IP Rotation: If you have access to multiple IP addresses, you can rotate them to avoid IP-based blocking.

7. Proxy Servers and VPNs: Use proxy servers or VPNs to mask your IP address. There are many services available that provide rotating proxies specifically for web scraping.

8. CAPTCHA Solving: Some websites employ CAPTCHAs to block bots. You might need to use a CAPTCHA solving service or implement a manual intervention step.

9. Headless Browsers: For complex websites, especially those loaded with JavaScript, consider using a headless browser like Puppeteer or Selenium. They can mimic human-like interactions more effectively.

10. Ethical Considerations: Always consider the ethical implications and legal aspects of web scraping. Obtain permission when possible and avoid scraping personal or sensitive information.

Remember, the goal is to be a good internet citizen: scrape responsibly, be respectful of the website's resources, and always comply with their terms of service and legal restrictions. If your scraping activities are causing issues for the website, you should reconsider your approach and possibly seek a more legitimate way to obtain the data, such as through an API provided by the site.