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Many web crawlers do not function properly and, even with proxy IP, are recognized and access restricted by the target site after some time. So what's the problem? How does a website identify a crawler? Let's explore that.
First, website identification method:
1. Frequency of unconventional access to a single IP
Websites use frequency monitoring to detect IP address activity. If an IP address visits the site frequently for a short period of time, exceeding the frequency of normal users, the site will recognize it as a crawler. In order to reduce the load on the server and protect its own resources, the website will take measures to limit the IP address that is visited too frequently.
Such restrictions can take different forms. One common way to do this is by setting an access rate limit, which limits the number of requests that each IP address can send in a specific time period. For example, websites can set up to allow only a certain number of requests per minute or hour from a certain IP address, and requests that exceed the limit will be rejected or delayed. Another approach is to adopt capTCHA authentication, which requires users to enter a captCHA for verification when they frequently access or perform sensitive actions to confirm that they are real users and not crawlers.
2. unconventional data traffic
When an IP generates abnormally high data traffic, it will also attract the attention of the website. When I talk about data traffic, I don't mean a single download, but a large number of concurrent requests. If an IP sends a large number of requests at the same time, it will cause a high load on the server, so the website will restrict it.
3. Repeat a lot of simple web browsing
Different users have different browsing speed and habits, and their browsing behavior will be different. If the same IP accesses a website page at the same speed, such as visiting a page every 3 seconds, it will arouse suspicion and be banned from the site. Even using proxy IP is difficult to circumvent this problem.
4. Crawler identification in HTTP:
To identify crawlers, websites typically check the User-Agent field in the HTTP request header. A crawler usually identifies itself with a specific user-agent string, but this is not absolute because a crawler can masquerading as a common browser User Agent to avoid detection.
5. JavaScript and dynamic content:
Websites can use JavaScript to generate dynamic content that makes it more difficult for crawlers to identify. Crawlers usually only get static content and cannot execute JavaScript code. By verifying the browser's ability to interpret and execute JavaScript, websites can distinguish between crawlers and real browsers.
6. Cookies and session tracking:
By setting cookies in the user's browser and tracking sessions, websites can distinguish between crawlers and real users. Crawlers typically do not have cookies or session information, and real users save and pass this data in the browser. Websites can use this information to determine the identity of visitors.
These are the methods commonly used by websites to identify crawlers. If you want to visit the target website without being easily identified, you should effectively avoid the above points and develop a reasonable crawling strategy. Of course, these are just some of the methods, want to reduce the risk of being identified in the reptile business, you can choose a high-quality residential agent.
Second,how does proxy IP help crawler ip evade anti-crawler mechanisms
① Hide the real IP address: The use of proxy IP can hide the real IP address of the crawler, so that the target website can not trace the source of the crawler. Anti-crawler systems usually restrict or block based on IP addresses, and by using proxy IP, IP addresses can be changed to increase the anonymity and concealability of crawlers.
② Avoid access frequency restrictions: Anti-crawler systems usually restrict frequent requests from the same IP address, such as setting access frequency limits or verification codes. By using proxy IP, different IP addresses can be rotated to simulate the behavior of multiple users, reducing the probability of being restricted by the anti-crawler system.
③ Simulation of geographical location and user behavior: some websites may be restricted or filtered according to the user's geographical location or behavior pattern, and the IP address of different regions or countries can be selected using proxy IP to simulate the behavior of real users. This reduces the likelihood of being identified as a crawler by anti-crawler systems.
It should be noted that different websites and anti-crawler systems may adopt different identification methods, so choose high-quality and stable proxy IP service providers, and reasonably configure the use of proxy IP to improve the effect of avoiding anti-crawler mechanisms.
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