有一种流行的方法叫做“画布指纹”，在这篇科学文章《网络永不遗忘》中有描述: 野外的持久跟踪机制。一旦你开始寻找它，你会惊讶于它被使用的频率。该方法创建一个唯一的指纹，该指纹对于每个浏览器/硬件组合都是一致的。

本文还介绍了其他持久跟踪方法，如evercookie、respawning http和Flash cookie以及cookie同步。

更多关于画布指纹的信息:

完美像素:HTML5中的指纹画布 https://en.wikipedia.org/wiki/Canvas_fingerprinting

我猜结论是我不能通过编程唯一地识别一台正在访问我的网站的计算机。

I have the following question. When i use a machine which has never visited my online banking web site i get asked for additional authentification. then, if i go back a second time to the online banking site i dont get asked the additional authentification. reading the answers to my question i decided it must be a cookie involved. therefore, i deleted all cookies in IE and relogged onto my online banking site fully expecting to be asked the authentification questions again. to my surprise i was not asked. doesnt this lead one to believe the bank is doing some kind of pc tagging which doesnt involve cookies?

此外，今天在谷歌搜索了很多之后，我发现了以下公司，他们声称出售一种解决方案，可以唯一地识别访问网站的机器。http://www.the41.com/products.asp。

我很感激所有好的信息，如果你能进一步澄清这些相互矛盾的信息，我将非常感激。

一个技巧:

Create 2 Registration Pages: First Registration Page: without any email or security check (just with username and password) Second Registration Page: with high security level (email verification request and security image and etc.) For customer satisfaction, and easy registration, default registration page should be the (First Registration Page) but in the (First Registration Page) there is a hidden restriction. It's IP Restriction. If an IP tried to register for second time, (for example less than 1 hour) instead of showing the block page. you can show the (Second Registration Page) automatically. in the (First Registration Page) you can set (for example: block 2 attempts from 1 ip for just 1 hour or 24 hours) and after (for example) 1 hour, you can open access from that ip automatically

请注意:(第一注册页)和(第二注册页)不应在分开的页面。你只写了一页。(例如:register.php)，并在第一PHP样式和第二PHP样式之间切换

你可能想尝试在evercookie中设置一个唯一的ID(它可以跨浏览器工作，见他们的常见问题): http://samy.pl/evercookie/

还有一家叫做ThreatMetrix的公司，被很多大公司用来解决这个问题: http://threatmetrix.com/our-solutions/solutions-by-product/trustdefender-id/ 它们相当昂贵，而且他们的其他一些产品也不太好，但他们的设备id运行良好。

最后，还有这个开源jquery实现的panopticlick的想法: https://github.com/carlo/jquery-browser-fingerprint 它现在看起来很不成熟，但可以扩展。

希望能有所帮助!

我觉得饼干可能就是你要找的东西;这是大多数网站唯一识别访问者的方式。

如果没有用户的合作，识别访问网站的电脑是不可能的。但是，如果他们允许，您可以存储一个cookie，以便在机器再次访问您的网站时识别它。关键在于，访问者是可控的;他们可以删除cookie，并随时以新访客的身份出现。