It sounds easy to use a crawler to access publicly available data from a website and turn it into structured data, but in reality, scraping web data is getting trickier, and most websites today have access bugs in their servers that restrict crawlers as soon as they are detected. However, for businesses and developers who need to crawl through large amounts of data for market research, competitor analysis, or other data collection needs, getting around these restrictions has become critical. In this article, we will cover some effective ways to break the limits of crawler data and help you smoothly get the data you need.
1. Use a proxy server
The proxy server acts as the intermediate layer between the user and the target website, hiding the real user IP address and providing multiple IP addresses for the user at the same time, thus allowing a large number of concurrent requests, avoiding being blocked by the website, and improving the efficiency and stability of data collection.
Some websites have adopted anti-crawling measures, which detect frequent requests or visits from the same IP address and treat them as crawling behavior, and then impose restrictive measures such as blocking IP or limiting access speed. By using a proxy server, you can hide the real IP address and send the request to the target website through the proxy server. The target website can only see the IP address of the proxy server but cannot obtain the IP address of the real user. This way, even if a large number of requests are made, the real IP address is not directly exposed, thus reducing the risk of being blocked.
In addition, a proxy server can provide users with multiple IP addresses, which can come from different geographic areas or devices. This multi-IP function is called IP pool, which allows users to constantly switch IP addresses during data capture, simulating the access behavior of different users. This dynamic IP switching makes data scraping more stealthy, reducing the likelihood of being identified by websites as crawlers.
There are other benefits to using a proxy server for data scraping. For example, proxy servers can implement load balancing, spreading requests across multiple proxy IP addresses, reducing the burden on the target website server. In addition, for websites or data sources that need to access different regions, the proxy server can provide the IP address of the corresponding geographic region, making data fetching more targeted and operable.
2. Set the user agent header
Websites often distinguish between real users and robot web crawlers by examining User-Agent information in HTTP headers. User-agent is an HTTP header field that contains information about the User Agent, such as the operating system, browser type, and version. By setting the appropriate user agent header, your crawler request can be disguised as a request from an ordinary user, thereby avoiding being identified as a crawler by the website and increasing the success rate of data scraping.
When crawling data, in general, we will use a specific crawling framework or tool, such as the Requests library commonly used in Python, Scrapy, etc. The default User-Agent header of these crawlers often contains the name and version information of the tool, which makes crawler requests easily recognized by websites as bot behavior.
To avoid being detected as a crawler, we can set the appropriate user-agent header to make the crawler request look more like a normal User's request. Typically, we can add User-Agent information to the crawler tool's HTTP request header by looking for the real browser's user-agent information. In this way, when the target website receives the request, it will assume that the real user is visiting and will not restrict or block it.
3. Use dynamic IP
When using a Web proxy, make sure the proxy service provider supports IP rotation. IP rotation is one of the best ways to send requests through a series of different IP addresses to crawl Web data and avoid being blocked from websites. Using the IP rotation function of the proxy service provider, you can capture data with different IP addresses, simulate the identity of multiple different users, and reduce the risk of suspicion and blocking.
4. Request frequency control
Controlling the frequency of requests is the key to circumventing the crawler data limit. Requests that are too frequent may trigger the site's anti-crawler mechanism, resulting in a block or restricted access. Therefore, it is recommended to set an appropriate request interval to simulate the access behavior of real users. In accordance with the site's anti-crawling strategy, a moderate extension of the request interval helps to maintain a low profile and complete the data crawl smoothly.
To sum up, breaking the crawler data limit requires a series of effective methods to hide the real IP address, simulate the real user behavior, and reasonably control the request frequency. Using proxy servers, setting user agent headers, dynamic IP rotation, and request frequency control are important strategies to circumvent restrictions.