In today's digital age, the data on a website becomes more and more important. However, in order to protect the security and stability of data, many websites have adopted anti-crawling mechanisms to identify and block access to crawlers. In this paper, we will discuss how websites identify crawlers and how they can use proxies to evade these anti-crawling mechanisms.

A. Methods of website identification crawlers

1. User behavior analysis: The website analyzes the user's access behavior to determine whether it is a crawler. For example, frequent requests, high-speed access speed, drone operations and other behaviors may be considered as crawler activities.

2. IP address-based identification: The website can determine whether it is a crawler by monitoring the source and usage of IP addresses. For example, a large number of requests coming from the same IP address, or IP addresses belonging to data centers or proxy service providers, etc., may be considered as crawlers. Some well-known crawlers use a specific range of IP addresses for access, so a website can filter based on these IP addresses.

3. CAPTCHA and human verification: In order to block crawlers' access, websites may use measures such as CAPTCHA or human verification to require users to perform manual verification to prove that they are real users.

4. User-Agent identification: Websites can determine whether a request comes from a crawler by checking the User-Agent header in HTTP requests. Common crawlers often have obvious User-Agent identifiers, such as "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)".

5. Request frequency limit: Websites can monitor the frequency of requests to identify if a crawler is visiting. If the requests are too frequent and beyond the range of normal users, the website may consider them as crawlers.

B, the use of proxies to avoid the anti-crawl mechanism

1. Use proxy IP: By using a proxy IP, you can hide the real IP address and simulate multiple different IP addresses for access. This can make it more difficult for crawlers to be identified by websites, as each request will use a different IP address. Choose a high quality proxy provider that can provide stable proxy IPs and support multiple geographic locations to choose from

2. IP Rotation: With the IP rotation function provided by the proxy service provider, you can automatically switch proxy IP addresses. This way you can simulate different user behavior and reduce the probability of being identified by the website. Changing proxy IPs regularly can increase the crawler's invisibility. You can use a proxy pool or automatic IP switching tool to automatically switch proxy IPs randomly to avoid being recognized as a crawler by websites.

3. Simulate real user behavior: The crawler can simulate the behavior of real users, such as simulating random access intervals, page clicks and scrolls, to avoid being recognized as a crawler by the website. This can be achieved by adjusting the request frequency and pattern of the crawler.

4. Using random User-Agents: By using a random User-Agent header in each request, the crawler can be made more anonymous and reduce the probability of being recognized by the website.

5. Handle CAPTCHA and human verification: If a website requires CAPTCHA or human verification, you can respond by using an automated tool or manually handling it. Automation tools can help you automate the filling of CAPTCHAs or simulate human-machine operations to increase efficiency.

Conclusion:

Websites identify crawlers by means of IP address identification, User-Agent identification, access pattern analysis, and JavaScript parsing. However, anti-crawling mechanisms can be evaded by using a proxy server. Proxy servers hiding real IPs, simulating User-Agents, adjusting request intervals, implementing distributed crawling, and choosing high-quality proxy service providers are all effective ways to evade anti-crawling mechanisms by using proxies.