Web crawlers play an important role in the Internet, with more than half of all traffic coming from web crawlers. However, in order to protect the information security of the website and prevent abuse, many websites will set up anti-crawling measures. When faced with the anti-crawling measures of websites, crawlers need to adopt corresponding strategies to ensure the smooth progress of crawling target data. Here are some strategies to be aware of when dealing with anti-crawling measures on your website:
1. Dynamic page restrictions
2. User behavior detection
Some sites will detect user behavior to determine whether it is a crawler. This may involve checking the user's Cookies, verifying information, etc. In response to such anti-crawling measures, crawlers may need to simulate real user behavior, including the reasonable setting of Cookies, processing verification information, etc., to avoid detection and interception by the website.
3, block the frequency of access to the collection of public data
Blocking the frequency of access to collect public data is one of the common anti-crawling measures of websites, websites will limit the number of visits of a single IP in a specific time to prevent excessive frequent access and protect the normal operation of the website. When crawlers need to grab data on a large scale, faced with this frequency limitation, they need to adopt some strategies to circumvent this limitation to ensure the smooth progress of the crawling process. Using proxy IP is a common and effective strategy to circumvent frequency restrictions on a single IP. Proxy IP allows crawlers to change IP addresses when requesting a website, thus simulating different user visits and avoiding overly centralized requests.
4. Use request header information
The use of request header information is one of the common strategies used by crawlers to avoid websites identifying crawlers based on request header information. The request header information contains some metadata, such as User-Agent and Referer fields, that the client sends to the server. By simulating the request header information of real users, crawlers can make the request look more like a visit from a real browser, reducing the probability of being detected by the website.
5. Set a reasonable request interval
Reasonable setting of request interval is one of the important strategies for reptilians to reduce the risk of being blocked. Sending requests too frequently may attract the attention of the website, be identified as crawling behavior by the website, and take corresponding anti-crawling measures, such as blocking IP addresses. In order to ensure that the crawler can carry out stable and continuous data collection, the crawler should set a reasonable request interval to avoid frequent visits to the same page in a short period of time. In summary, the anti-crawling measures to deal with the website need to take a multi-faceted strategy, including dealing with dynamic pages, simulating user behavior, using proxy IP, modifying the request header information, etc.