How to detect whether a web website has been crawled
How to detect whether the web site has been crawled, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain in detail for you, people with this need can come to learn, I hope you can gain something.
With the development of big data era, data and information has become the benchmark of a lot of work. The effective extraction and utilization of this kind of information has become a major challenge. In order to solve this problem, crawlers specializing in crawling relevant web resources came into being. Nowadays, more and more websites have established anti-crawler mechanisms, so how do these websites find that crawlers are collecting website information?
1. Block IP detection.
That is, the IP access speed of the user is detected. If the access speed reaches the set threshold, the restriction blocking IP is turned on, so that the crawler can no longer obtain data.
2. Request header detection. The crawler is not a user and has no other characteristics during access.
The site can detect whether the crawler is a user or a crawler by detecting the crawler's request header.
3. Check the verification code and limit the setting of the login verification code.
If you do not enter the correct CAPTCHA, you will not be able to get this information. Because crawlers can use other tools to identify CAPTCHA, the site continues to deepen the difficulty of verifying the code, from ordinary pure data research CAPTCHA to mixed CAPTCHA, sliding CAPTCHA, and so on.
4. Cookie detection.
The browser will save the cookies so that the website will test the cookie to determine if you are a real user. If it is not camouflaged, restrict access is triggered.
Through the above methods, the website can monitor the crawlers, and the crawler practitioners can also break down one by one according to these methods. Crawlers and anti-reptiles are a long battle.
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