通过CRON批量发起CURL请求抓取站点内容是否会被判定为攻击？

Great question—this is a super common concern when setting up scheduled web scraping, and the short answer is: yes, this absolutely could get you flagged as an attacker if you're not careful. Let me break down why, and what you can do to avoid it:

Why you might get flagged #

• Rate limits & server load: Most websites (even small ones) have unwritten or explicit rate limits to keep their servers from being overwhelmed. Blasting hundreds of curl requests in a tight window looks identical to a brute-force attack or a small DDoS attempt to their security systems. Even if you space them out a little, if your total daily request volume is way higher than a normal human would generate, you'll trigger alarms.
• Bot-like patterns: Curl requests on their own are easy to spot. If you're using the default user agent, not storing cookies, crawling pages in a perfect sequential order (e.g., /page1, /page2, /page3), or not adding delays between requests, the site's anti-bot tools will immediately know you're not a real person browsing.
• Potential consequences: The best case is you start getting 429 (Too Many Requests) or 403 (Forbidden) responses. Worst case? Your IP gets permanently blocked, or the site serves you fake data to throw off your scraping efforts.

How to stay under the radar #

Here are practical steps to make your scheduled scraping look more like legitimate traffic:

• Add delays between requests: Throw a sleep 2 (or even sleep 1) between each curl call in your script. Even a 1-3 second pause mimics how a real person would navigate between pages, and it drastically reduces the chance of triggering rate limits.
• Spoof user agents: Use the -A flag in curl to pretend you're a real browser. For example:

  curl -A "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36" https://target-site.com/page1
  

  Rotate different user agents occasionally to make it even harder to track.
• Respect robots.txt: Always check the site's /robots.txt file first. If it disallows crawling the pages you're targeting, either skip them or reach out to the site owner for permission—ignoring this is a quick way to get blocked.
• Split your cron job: Instead of running all hundreds of requests in one batch, split them into smaller chunks throughout the day. For example, run 20 requests every hour instead of 240 all at once. This spreads out the load and looks more natural.
• Leverage caching smartly: Don't re-request pages unless they've changed. Use curl to check the Last-Modified or ETag headers, and only download the page again if the content has been updated. This cuts down on unnecessary requests entirely.
• Ask for permission: If the site is small or has a contact page, sending a polite note explaining what you're scraping and why might get you explicit permission. This eliminates all risk of being flagged as an attacker.

内容的提问来源于stack exchange，提问作者Alvaro