第三方如何“跟踪 cookie"工作? [英] How do Third-Party "tracking cookies" work?

问题描述

我在这里阅读了这个问题:互联网广告商如何使用第三方 Cookie?关于第三方跟踪 cookie 的工作原理，但我仍然很困惑.我不明白如果我访问网站A(一个有广告的普通网站)网站B(一个广告网站)如何给我的电脑分配一个ID，然后弄清楚我在网站A上，然后其他网站有它的广告.

I have read this question here: How Do Internet Advertisers Use Third-Party Cookies? on how third-party tracking cookies work, but am still very confused. I don't understand how if I visit Website A (a normal website with ads) how Website B (an advertising website) can assign my computer an ID, and then figure out that I was on website A, and other websites after it that have its ads.

推荐答案

首先，cookie 是通过 HTTP 标头设置和检索的.如果您的浏览器向 http://example.com 发送请求，则响应可能会返回一个标有 Set-Cookie 的标头: foo=bar.您的浏览器会存储此 cookie，并且在对 http://example.com 的任何后续请求中，您的浏览器将发送 foo=barCookie 标头中的 code>.(或者至少在 cookie 过期或被删除之前.)浏览器将带有 any 请求的 foo=bar cookie 发送到 http://example.com，无论是谁发起请求或上下文是什么.如果 http://example2.com 包含标签 <img src="http://example.com/img.jpg">，那么浏览器在获取http://example时会发送cookiefoo=bar.com/img.jpg，即使 http://example2.com 负责发送的请求.

First, cookies are set and retrieved through HTTP headers. If your browser sends a request to http://example.com, then the response might come back with a header that says Set-Cookie: foo=bar. Your browser stores this cookie, and on any subsequent requests to http://example.com, your browser will send foo=bar in the Cookie header. (Or at least until the cookie expires or is deleted.) The browser sends the foo=bar cookie with any request to http://example.com, regardless of who initiated the request or what the context is. If http://example2.com contains the tag <img src="http://example.com/img.jpg">, then the browser will send the cookie foo=bar when it fetches http://example.com/img.jpg, even though http://example2.com is responsible for the request being sent.

因此，如果网站 A 包含由网站 B 提供的广告，则网站 B 可以在您的浏览器中设置 cookie.例如，也许网站 A 使用 <iframe src="http://websiteB.com/ad.html></iframe> 来投放来自网站 B 的广告.然后当您的浏览器转到要获取 http://websiteB.com/ad.html，响应将返回一个 Set-Cookie 标头，该标头设置了具有一些唯一随机字符串的 cookie.如果网站 C 还包含来自网站 B 的广告，那么当从网站 B 获取网站 C 上的广告时，将发送该唯一 cookie.

So, if website A contains an ad that is served by website B, then website B can set a cookie in your browser. For example, maybe website A uses <iframe src="http://websiteB.com/ad.html></iframe> to serve the ad from website B. Then when your browser goes to fetch http://websiteB.com/ad.html, the response will come back with a Set-Cookie header that sets a cookie with some unique random string. If website C also includes an ad from website B, then that unique cookie will be sent when the ad on website C is fetched from website B.

至于网站 B 如何知道您正在访问的实际网站，有多种方式.在某些情况下，当浏览器向一个网站发送请求时，它会告诉该网站您来自哪个网站.因此，当浏览器去获取 http://websiteB.com/ad.html 时，它可能包含 HTTP 标头 Referer: http://websiteA.com网站 B 发现请求是由网站 A 发起的.每次网站 B 看到它分配给您的唯一随机字符串时，它都会检查 Referer 标头以将您去过的地方添加到它的日志中.如果网站 A 与网站 B 合作，则 A 可以直接告诉 B 您来自网站 A.例如，网站 A 可以使用 <iframe src="http://websiteB.com/ad.html?referer=websiteA.com">，然后网站B就会在查询字符串中看到referer.

As far as how website B knows which actual website you're visiting, there are a variety of ways. In some cases, when the browser sends a request to one website, it tells the website which website you're coming from. So when the browser goes to fetch http://websiteB.com/ad.html, it might include the HTTP header Referer: http://websiteA.com that tells website B that the request was initiated by website A. Every time website B sees the unique random string that it assigned to you, it can check the Referer header to add to its log of where you've been. If website A is cooperating with website B, A can just directly tell B that you're coming from website A. For example, website A could include the ad from website B by using <iframe src="http://websiteB.com/ad.html?referer=websiteA.com">, and then website B will see the referer in the query string.

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