I. Introduction

With the rapid development of the Internet, data has become an important basis for corporate decision-making. As an important means of obtaining network data, crawler technology is widely used in various fields. 

However, in the face of the increasingly enhanced anti-crawling mechanism of websites, how to ensure efficient and stable crawling by crawlers has become an urgent problem to be solved. This article will focus on the practical application of rotating ISP proxy in crawler crawling, and explore its principles, methods and practical effects.

2. Overview of anti-crawling mechanism

Before discussing the application of rotating ISP proxy in crawler crawling, let's first understand the common anti-crawling mechanism. The anti-crawling mechanism is a series of technical means used by websites to protect their own data security and prevent malicious crawlers from making large and frequent visits to the website. 

Common anti-crawling mechanisms include verification codes, IP blocking, request frequency control, restrictions based on user behavior, and User-proxy detection, etc. The existence of these anti-crawling mechanisms brings great challenges to crawler crawling.

3. Principles and advantages of rotating ISP proxies

Rotating ISP proxy is a method to bypass the anti-crawling mechanism of the website by constantly changing IP addresses. The principle is to use proxy servers provided by multiple ISPs (Internet Service Providers) to dynamically change the IP address requested by the crawler, thereby avoiding being identified and blocked by the website. The advantages of rotating ISP proxies are:

Improve crawler crawling efficiency: By constantly changing IP addresses, you can bypass the website's IP blocking and request frequency control, allowing crawlers to obtain target data more quickly and stably.

Increase the anonymity of the crawler: Since each request uses a different IP address, the behavior of the crawler is more difficult to track and identify, increasing the anonymity of the crawler.

Reduce the risk of being crawled: Due to the use of proxy servers provided by multiple ISPs, even if a proxy server is blocked by the website, you can continue to crawl by changing other proxy servers, reducing the risk of being crawled.

4. Practical application of rotating ISP proxy in crawler crawling

During the crawler crawling process, the application of rotating ISP proxy mainly includes the following steps:

Obtain the proxy IP list: First, you need to obtain a certain number of ISP proxy IP lists. These proxy IPs can be obtained from public proxy IP websites or by purchasing proxy IP services. When obtaining a proxy IP, you need to pay attention to factors such as the anonymity, stability, and speed of the proxy IP.

Test the availability of proxy IPs: After obtaining the proxy IP list, you need to conduct a usability test on these proxy IPs. You can write a simple test program and use network request tools such as the requests library to send HTTP requests to check whether the proxy IP can successfully connect to the target website and return a correct response. Unusable proxy IPs need to be removed from the list in time.

Dynamically switch proxy IP: During the crawler crawling process, the proxy IP needs to be dynamically switched as needed. This can be done by writing a proxy IP manager class that is responsible for getting the available proxy IP from the proxy IP list and setting it as the Proxy-Authorization field in the request header every time an HTTP request is sent. 

At the same time, you need to set a timer or counter to automatically change the proxy IP when a certain number of requests or time interval is reached.

Monitoring and adjustment: During the crawler running process, it is necessary to monitor the usage of the proxy IP and the response of the website in real time. If you find that a certain proxy IP is frequently blocked or the website responds too slowly to a certain proxy IP, you need to adjust the proxy IP list or change other proxy IPs in time. 

In addition, the crawler strategy needs to be adjusted in time according to the update status of the website to adapt to changes in the anti-crawling mechanism of the website.

5. Conclusion

To sum up, rotating ISP proxy technology has significant advantages and practical effects in crawler crawling. By constantly changing IP addresses and dynamically adjusting crawler strategies, you can bypass the anti-crawling mechanism of the website, improve crawler crawling efficiency and anonymity, and reduce the risk of being crawled. 

Therefore, in practical applications, we can combine specific business needs and the characteristics of the anti-crawling mechanism of the website, and flexibly use rotating ISP proxy technology to improve the performance and stability of the crawler.