通过HTTP连接只能获得少量信息。

IP - But as others have said, this is not fixed for many, if not most Internet users due to their ISP's dynamic allocation policies. Useragent String - Nearly all browsers send what kind of browser they are with every request. However, this can be set by the user in many browsers today. Collection of request fields - There are other fields sent with each request, such as supported encodings, etc. These, if used in the aggregate can help to ID a user's machine, but again are browser dependent and can be changed. Cookies - Setting a cookie is another way to identify a machine, or more specifically a browser on a machine, but as others have said, these can be deleted, or turned off by the users, and are only applicable on a browser, not a machine.

So, the correct response is that you cannot achieve what you would live via the HTTP over IP protocols alone. However, using a combination of cookies, as well as IP, and the fields in the HTTP request, you have a good chance at guessing, sort of, what machine it is. Users tend to use only one browser, and often from one machine, so this may be fairly relieable, but this will vary depending on the audience...techies are more likely to mess with this stuff, and use more machines/browsers. Additionally, this could even be coupled with some attempt to geo-locate the IP, and use that data as well. But in any case, there is no solution that will be correct all of the time.

我将使用cookie和flash cookie的组合来做到这一点。创建一个GUID并将其存储在一个cookie中。如果cookie不存在，请尝试从flash cookie中读取它。如果仍未找到，则创建它并将其写入flash cookie。通过这种方式，您可以跨浏览器共享相同的GUID。

这些人开发了一种指纹识别方法，可以非常准确地识别用户:

https://panopticlick.eff.org/static/browser-uniqueness.pdf

We investigate the degree to which modern web browsers are subject to “device fingerprinting” via the version and configuration information that they will transmit to websites upon request. We implemented one possible fingerprinting algorithm, and collected these fingerprints from a large sample of browsers that visited our test side, panopticlick.eff.org. We observe that the distribution of our finger- print contains at least 18.1 bits of entropy, meaning that if we pick a browser at random, at best we expect that only one in 286,777 other browsers will share its fingerprint. Among browsers that support Flash or Java, the situation is worse, with the average browser carrying at least 18.8 bits of identifying information. 94.2% of browsers with Flash or Java were unique in our sample.

通过观察回访用户，我们估计浏览器指纹随时间变化的速度。在我们的样本中，指纹变化很大 很快，但即使是一个简单的启发式通常也能猜出指纹是先前观察到的浏览器的“升级”版本 指纹，99.1%的猜测正确率和假阳性率只有 0.86%。

We discuss what privacy threat browser fingerprinting poses in practice, and what countermeasures may be appropriate to prevent it. There is a tradeoff between protection against fingerprintability and certain kinds of debuggability, which in current browsers is weighted heavily against privacy. Paradoxically, anti-fingerprinting privacy technologies can be self- defeating if they are not used by a sufficient number of people; we show that some privacy measures currently fall victim to this paradox, but others do not.

与前面的解决方案一样，cookie是一个很好的方法，但要注意它们可以识别浏览器。如果我先用火狐浏览器访问一个网站，然后再用ie浏览器访问，两次访问都会分别存储cookie。一些用户也禁用cookie(但更多的人禁用JavaScript)。

另一种需要考虑的方法是IP和主机名标识(请注意，对于拨号/非静态IP用户，这些可能有所不同，AOL也使用通用IP)。然而，由于这只识别网络，这可能不像cookie那样工作。

我的文章可能不是一个解决方案，但我可以提供一个例子，这个功能已经实现。

如果你第一次在电脑上访问www.supertorrents.org的注册页面，没问题。但如果您刷新页面或再次打开页面，它会识别出您之前访问过该页面。真正的美妙之处在于——即使你重新安装Windows或其他操作系统，它也能识别出来。

我在某处读到，他们存储CPU ID。虽然我不知道他们是怎么做到的，但我非常怀疑，他们可能使用MAC地址来做到这一点。

如果我知道怎么做，我一定会分享的。

实际上，您想做的事情无法实现，因为协议不允许这样做。如果静态ip被普遍使用，那么你可能就能做到这一点。它们不是，所以你不能。

如果您真的想要识别用户，请让他们登录。

因为它们可能会移动到你网站上的不同页面，你需要一种方法来跟踪它们的移动。

只要他们登录了，你就可以通过cookie /链接参数/信标等跟踪他们在你网站上的会话，你就可以很确定他们在这段时间内使用的是同一台计算机。

最终，如果你的用户没有使用你自己的本地网络，也没有静态IP地址，说这能告诉你他们在使用哪台计算机是不正确的。

如果你想要做的事情是在用户的合作下完成的，每个cookie只有一个用户，他们使用单一的网络浏览器，那就使用cookie。