Web crawlers play a big role in the Internet. More than half of the traffic comes from web crawlers. If a website does not set up an anti-crawling mechanism, the information of the website will be transparent. Therefore, most websites will set up an anti-crawling mechanism. How to break through if you encounter anti-web crawler measures?
Why is there an anti-crawling mechanism?
The anti-crawling mechanism is to prevent web crawlers from making excessive access requests to the website, which will cause server overload, network congestion, data leakage and other problems. The anti-crawling mechanism is usually set by website administrators or developers to limit the access rate or frequency of crawlers.
Some websites may have sensitive information, such as financial data or personal information. In order to protect this information, they need to take some measures to prevent unwelcome access and attacks.
Crawler programs can automatically crawl and extract data by simulating browser behavior on the website, which may have a serious impact on the website, including reducing the response speed of the website, blocking services, consuming resources, etc.
The anti-crawling mechanism can limit the access rate of crawlers to ensure the normal operation of website services while protecting sensitive information on the website from being abused.
In addition, some people may use crawlers to maliciously attack websites, such as using crawlers to brute-force passwords, inject malicious code, etc. In order to prevent these attacks, websites need to take anti-crawling measures.
How to solve the anti-crawling mechanism when crawling
When encountering anti-crawling mechanisms, using HTTP can be a solution, because the real IP address and user identifier of the crawler can be hidden, making the crawler's access look like it comes from different places and devices, thereby reducing the risk of being detected by the anti-crawling mechanism.
The following are some common ways to use HTTP to solve anti-crawling mechanisms:
1. Use multiple IP addresses: You can use multiple IP addresses to visit the target website in turn to avoid frequent access to a single IP address, thereby reducing the risk of being detected by the anti-crawling mechanism. You can use public IP or purchase paid IP services.
2. Randomly select IP addresses: When visiting the target website, you can randomly select an IP address to visit, thereby avoiding using the same IP address every time. You can use IP pools to manage and rotate IP addresses.
3. Set the IP address access frequency: You can set the IP address access frequency according to the anti-crawling mechanism of the target website to avoid excessive access and detection. Some IP services provide a rate limit function that can control the access rate of each IP.
4. Use different user identifiers: In addition to using IP addresses, you can also use different user identifiers, such as changing the browser type, operating system, language, etc., to simulate different user access behaviors, thereby reducing the risk of being detected by anti-crawling mechanisms.
It should be noted that using HTTP is not a perfect solution, because some anti-crawling mechanisms will also detect IP addresses and user identifiers, so the use of HTTP should be cautious, and the strategy needs to be constantly adjusted and optimized to adapt to different anti-crawling mechanisms.