Three common anti-reptile methods

Python crawler is a program or script that can automatically grab network data according to certain rules. It has the characteristics of fast and efficient, which can save a lot of time and cost. However, due to the frequent crawling behavior of Python crawlers, many servers have taken certain restrictive measures in order to protect their own resources, that is, we often say anti-crawler means to prevent the continued collection of Python crawlers. In this article, we will cover three common anti-reptile methods to help you understand and deal with these limitations.

1. Limit the request Headers

Limiting Headers is one of the most common and basic anti-crawler measures, and it is used to initially determine whether a request is coming from a real browser operation. Headers is a set of fields in an HTTP request that is used to pass additional information to the server. One of the most important fields is User-Agent, which identifies the type and version of the client that sent the request. Websites usually check the user-agent field to see if the request is coming from a real browser, because the browser used by the average User will have specific user-agent information, and the crawler may use the default user-agent or a custom user-agent, thereby exposing its crawler identity.

To get around the restrictions on Headers, crawlers need to simulate requests from real browsers, making the information in Headers look more like a request from an ordinary user. Specific measures include:

User-Agent Settings: Set User-Agent to a common browser, such as Chrome and Firefox, and the corresponding version information. This makes the request look more like it came from a real browser.

Referer setting: Some websites check the Referer field to determine the source of the request. The crawler can set the Referer field as the URL of the target website, indicating that the request is jumped from the target website, increasing the legitimacy of the request.

①What are the advantages and disadvantages of the HTTP p

Accept-Encoding Settings: The crawler can set the Accept-Encoding field to specify the content encoding supported, common ones include gzip and deflate. This indicates to the server that the crawler supports the compressed format, reducing the amount of data transferred.

Other field Settings: According to the specific requirements of the target website, other fields, such as authorization and Cookie, may need to be set to meet the authentication requirements of the website.

2. Limit the request IP address

Restricting the requested IP is one of the common anti-crawler measures for websites. When a crawler makes frequent crawls, if the same IP address sends a large number of requests in a row, the website may flag that IP as a crawler or frequent visitor and take restrictive measures, such as denying further requests for that IP or returning a 403 Forbidden access error. This restriction is designed to protect the site from malicious crawlers while safeguarding the access experience of normal users.

To cope with the limitations of the requested IP, the crawler can consider using proxy IP. Proxy IP addresses are used to forward requests through third-party proxy servers to hide real client IP addresses and anonymously access target websites. Using a proxy IP has the following advantages:

Hide real IP: Using proxy IP can hide real client IP and avoid being identified by websites as crawlers or frequent visitors.

IP switching: Proxy IP service providers usually provide a large number of IP addresses, and crawlers can constantly switch IP addresses to reduce the risk of being blocked.

②Three common application scenarios of proxy IP addresses

Improve crawler stability: By using proxy IP, crawlers can avoid the problem of limited request IP and ensure the continuous operation and stability of crawlers.

There are also some issues to be aware of when using proxy IP:

Select a reliable proxy IP service provider: Ensure that you select a stable and reliable proxy IP service provider to ensure the quality and availability of proxy IP addresses.

Avoid excessive frequent access: Although using proxy IP can circumvent the problem of the request IP being restricted, excessive frequent access may still trigger other anti-reptile mechanisms, so the frequency of access needs to be reasonably controlled.

Monitor IP address usage: Periodically monitor proxy IP address usage to ensure IP address stability and validity.

3. Limit request cookies

Some websites require the user to log in to get the data, so they check the Cookie information in the request to see if the user is logged in. If the crawler can't log in or can't stay logged in, it may be because the crawler's Cookie was found by the website. In order to solve this problem, the crawler needs to ensure that the crawler's Cookie information is valid and legal. You can simulate the login process to obtain legitimate cookies, and add the correct Cookie information to the request to maintain the login status, so that you can normally access the page that requires login permission.

When using Python crawlers for data scraping, we need to take care to avoid common anti-crawler methods. Proper setting of Headers, use of proxy IP, and valid Cookie information are key to resolving these limitations. At the same time, we should also abide by the rules of the use of the website, avoid excessive burden on the website, and maintain a reasonable crawling frequency to ensure the stability and efficiency of the crawler work.