How does a website identify crawler users?

The development of the Internet era makes the work inseparable from the network data, and many individuals or enterprises want to extract and use these information data. In order to solve this business demand, crawler tools to crawl related web pages have gradually emerged. However, in order to maintain the proper operation of the website and protect the user experience, many websites have set up access mechanisms to identify and block crawling users. So, how does a website detect crawlers?

1, detect the user IP access speed:

On the Internet, a crawler is an automated program that can quickly extract large amounts of data from web pages. While crawlers are very useful in some scenarios, such as search engine crawling and data mining, in other cases they may put excessive load pressure on the website and even interfere with the normal user experience. Therefore, the site manager needs to set a threshold for access speed, and once the access speed exceeding the set threshold is detected, appropriate measures will be taken to prevent the crawler from continuing to obtain data.

①What are the advantages of exclusive representation?

In order to monitor access speed, website managers can use various technologies and algorithms to monitor users' access behavior in real time. A common method is to analyze the user's request interval to determine its access speed. Normal user access tends to have a certain time interval, while crawlers usually request data continuously at a very fast speed, so their request time interval is shorter. When a website detects that an IP address is being accessed faster than a set threshold, it determines that the IP address is likely to be a crawler and takes measures to prevent further access.

2. Detection request header:

On the Internet, different users use different browsers and devices to access, so the information in their request headers will be different. Crawlers typically send requests using automated scripts whose request headers may differ significantly from those of ordinary users. Website administrators can detect some characteristic information in the request header, such as the user-agent field, to determine whether a normal User or a crawler is accessing. The User-Agent field is an identifier attached to the browser when it sends a request to tell the server its identity and capabilities. Different browsers and devices will contain different information in the User-Agent field, such as the name and version of the browser and the type and version of the operating system. When an ordinary User uses a browser to access a website, its user-agent field is real, reflecting its real browser and device information. When a crawler visits a website, because it is an automated script that sends requests, its User-Agent field may be fixed or customized, which is obviously different from the User-Agent field of a real browser.

By comparing the User-Agent field in the request header, the website can more accurately determine whether the visitor is a crawler. Once the use of an unconventional or fixed User-Agent field is detected, the site has reason to suspect that it is a crawler and take appropriate measures to limit it. This approach may work for some simple crawlers, but for advanced crawlers, they may forge the request header to look more like a real user's request, thus avoiding detection.

②The advantages and disadvantages of dynamic IP versus static IP

3. Verification code detection:

In order to prevent crawlers from bypassing detection, many websites set up captcha verification mechanisms. When a website suspects that a visitor may be a crawler, it asks them to enter a verification code for verification. This can effectively prevent most crawlers from illegally accessing the website.

4. Cookie detection:

Websites set cookies to track the user's visit behavior and status. Crawlers generally do not support cookies or save cookies, whereas the browsers of ordinary users save cookies automatically. Therefore, the website can detect whether the visitor is carrying a Cookie to determine whether it is a crawler or an ordinary user.

The above methods are only part of the means for websites to identify crawler users, in fact, websites may use a variety of techniques and algorithms to identify crawlers. Due to the emergence of access mechanisms, proxy IP has become widely known and widely used. Using rotating residential proxy IP can reduce the chances of IP being restricted while improving the efficiency of crawlers. When using crawler tools, we should abide by the website's access rules and avoid excessive access to the website in order to maintain a good network environment and user experience.