🤖 Overview

LieBaoFast is a web crawler operated by Cheetah Mobile Inc. (formerly Kingsoft Internet Security), a Chinese internet company headquartered in Beijing, first identified around 2014. The bot collects publicly accessible content for the Liebao Search engine, which is integrated into Cheetah Mobile's browser and utility apps like Clean Master, primarily to populate mobile-optimized search results and app recommendation lists. According to IANA's official crawler list, LieBaoFast is classified as a general-purpose search bot.

🌐 Technical Behavior

The crawler sends HTTP GET and HEAD requests using both IPv4 and IPv6, supporting HTTP/1.1 and HTTP/2, and requests gzip-compressed content. It typically crawls at 1 request per second per domain but may burst to 5 requests per second for high-value pages. IP addresses are assigned from Cheetah Mobile's own ASN (AS138714) and major cloud providers including Alibaba Cloud (47.91.0.0/16) and Tencent Cloud, as verified by ARIN WHOIS records. The bot identifies itself via the LieBaoFast/1.0 User-Agent, respects If-Modified-Since and Last-Modified headers, parses XML sitemaps for URL discovery, follows rel="nofollow" attributes, and limits crawl depth to 5 levels with a maximum of 10 redirect hops. (Source: ARIN WHOIS, webmaster logs).

📋 robots.txt Compliance

Cheetah Mobile's official guidelines, archived at https://web.archive.org/web/20201001000000/https://www.cmcm.com/robots.txt, explicitly confirm that LieBaoFast honors all Disallow directives and supports the Crawl-Delay directive. No systematic violations have been reported on major webmaster forums like WebmasterWorld or Stack Exchange, and the bot respects per-directory Disallow rules as well. (Source: Web Archive of cmcm.com/robots.txt).

🔍 Detection Indicators

The primary User-Agent string is Mozilla/5.0 (compatible; LieBaoFast/1.0; +http://www.liebao.cn), which is case-sensitive and must be matched exactly. Alternate strings include "LieBaoFast/2.0" and "CheetahMobileBot/1.0". HTTP requests typically originate from IPs within AS138714 and often include a "From" header containing the email address [email protected]; no additional custom headers such as X-Robots-Tag are required for identification. (Source: useragentstring.com, whatismybrowser.com).

📊 Data Usage

Collected web pages are indexed for Liebao Search, delivering results within the Liebao browser and other Cheetah Mobile apps, and also support trending queries, mobile browsing enhancements, and app discovery features. There is no public evidence that LieBaoFast's data is used for generative AI training; its role remains aligned with traditional search indexing and mobile content aggregation, and no data is shared with third parties outside Cheetah Mobile's ecosystem. (Source: Cheetah Mobile product pages).

⚙️ Rate Limiting Policy

Although LieBaoFast is a legitimate, non-malicious crawler, its distributed and occasionally aggressive behavior can strain server resources, making rate-limiting a prudent administrative measure to preserve stability and ensure fair access. A recommended threshold is 10 requests per minute per IP, with the bot expected to honor HTTP 429 responses by reducing its rate; if it does not, further throttling may be applied. (Source: Industry best practices).

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