原文地址：http://www.theonionrouter.com/about/overview.html.en#overview

概述

“The Tor network is a group of?volunteer-operated servers that allows people to improve their privacy and security on the Internet. Tor's users employ this network by connecting through a series of virtual tunnels rather than making a direct connection, thus allowing both organizations and individuals to share information over public networks without compromising their privacy. Along the same line, Tor is an effective censorship circumvention tool, allowing its users to reach otherwise blocked destinations or content. Tor can also be used as a building block for software developers to create new communication tools with built-in privacy features.”

Tor網絡由一組自運行服務器組成，滿足了人們提升網絡隱私和安全等級的需要。與傳統直連不同，tor用戶通過連接一系列虛擬隧道來訪問網絡。這樣一來，機構和個人都不在需要以妥協隱私為代價來進行公共網絡活動。同時，tor也是一款優秀的避開審查制度的工具。使用者可以訪問本被禁止的地址或內容。它還在一些時候被軟件開發者們內置于帶隱私功能的通訊類軟件。

“Individuals use Tor to keep websites from tracking them and their family members, or to connect to news sites, instant messaging services, or the like when these are blocked by their local Internet providers. Tor's?onion services?let users publish web sites and other services without needing to reveal the location of the site. Individuals also use Tor for socially sensitive communication: chat rooms and web forums for rape and abuse survivors, or people with illnesses.”

個人用戶可通過tor擺脫網站的跟蹤、訪問當地運營商禁掉的新聞站點和網絡服務。Tor提供的“洋蔥服務”允許用戶在不暴露真實地址的情況下發布網站以及提供服務！個人用戶同樣可以用其交流一些較敏感的話題。如：

“Journalists use Tor to communicate more safely with whistleblowers and dissidents. Non-governmental organizations (NGOs) use Tor to allow their workers to connect to their home website while they're in a foreign country, without notifying everybody nearby that they're working with that organization.”

新聞工作者可以用其保證自身不遭受打擊報復。NGO的工作人員可以通過Tor在異國訪問組織的網站。并且不需要暴露自己和該組織的關系。

Groups such as Indymedia recommend Tor for safeguarding their members' online privacy and security. Activist groups like the Electronic Frontier Foundation (EFF) recommend Tor as a mechanism for maintaining civil liberties online. Corporations use Tor as a safe way to conduct competitive analysis, and to protect sensitive procurement patterns from eavesdroppers. They also use it to replace traditional VPNs, which reveal the exact amount and timing of communication. Which locations have employees working late? Which locations have employees consulting job-hunting websites? Which research divisions are communicating with the company's patent lawyers?

如Indymedia之類的團體出于保護其成員的網絡隱私和安全也建議成員使用Tor。激進主義團體如EFF也推薦使用Tor作為一種維護網絡自由的機制。大型集團經常使用Tor來防止被監聽，以確保能安全地實施競爭調查以及保護敏感的采購規律。Tor也被用于替代傳統虛擬代理，其能夠顯示準確的通訊時間和通訊量。哪個地區的員工加班晚？那個地區的雇員在找獵頭公司？哪家調查機構和公司的專利律師有聯絡？

A branch of the U.S. Navy uses Tor for open source intelligence gathering, and one of its teams used Tor while deployed in the Middle East recently. Law enforcement uses Tor for visiting or surveilling web sites without leaving government IP addresses in their web logs, and for security during sting operations.

一直美國海軍部隊使用Tor公開招募智囊，其中一支小隊在最近的中東部署中也用到了Tor。一些執法機關用Tor訪問監控站點而不會在其網絡日志中留下政府的IP地址，這也保證了釣魚執法的安全有效。

The variety of people who use Tor is actually?part of what makes it so secure. Tor hides you among?the other users on the network, so the more populous and diverse the user base for Tor is, the more your anonymity will be protected.

用戶多樣性是保證Tor安全性中的重要一環。Tor讓你隱藏在網絡的其他用戶之中。因此，Tor的用戶群體越大越多樣，你的隱匿性就會越發得到保護。

為什么需要Tor？

Using Tor protects you against a common form of Internet surveillance known as "traffic analysis." Traffic analysis can be used to infer who is talking to whom over a public network. Knowing the source and destination of your Internet traffic allows others to track your behavior and interests. This can impact your checkbook if, for example, an e-commerce site uses price discrimination based on your country or institution of origin. It can even threaten your job and physical safety by revealing who and where you are. For example, if you're travelling abroad and you connect to your employer's computers to check or send mail, you can inadvertently reveal your national origin and professional affiliation to anyone observing the network, even if the connection is encrypted.

使用Tor能讓你有效避免一種叫做“流量分析”的東東。流量分析可以被用于找出公共網絡上哪兩個人在通信。通過了解你的源和目的地址，其他人可以由此分析你的行為規律和喜好。這很大程度上會影響你的決策，比如說，一個電商網站可以根據你的人所在國家以及機構制定價格歧視策略。說得嚴重一些，它甚至有可能暴露你的實際地理位置，從而對你的現實人身安全造成威脅。比如說，如果你出國了然后你連了你雇主的計算機查發郵件，這個時候其實你已經一不小心就把你的國籍和單位信息暴露給了這個監聽這個網絡的人，就算鏈接是加密的也不例外。

How does traffic analysis work? Internet data packets have two parts: a data payload and a header used for routing. The data payload is whatever is being sent, whether that's an email message, a web page, or an audio file. Even if you encrypt the data payload of your communications, traffic analysis still reveals a great deal about what you're doing and, possibly, what you're saying. That's because it focuses on the header, which discloses source, destination, size, timing, and so on.

流量分析是怎么回事？網絡數據包分兩部分：用戶數據和用來路由的數據包頭。數據部分就是你真正要發送的部分，可能是一封電郵，一個網頁，或者一個音頻文件。即使你在通信過程中對數據部分進行了加密，數據分析仍然還是能分析出一大部分你正在干的事兒或者你正在說的話。那是因為它主要分析數據包頭，包頭里包含有源、目的、大小、時間以及其他種種信息。

A basic problem for the privacy minded is that the recipient of your communications can see that you sent it by looking at headers. So can authorized intermediaries like Internet service providers, and sometimes unauthorized intermediaries as well. A very simple form of traffic analysis might involve sitting somewhere between sender and recipient on the network, looking at headers.

從隱私的角度來說，有一個基礎的問題要解決，就是接收方可以通過數據包頭部信息知道是你發送了這些數據。被授權的網絡中間方也可以看到，例如，運營商們。更可怕的是，有的時候，甚至未被授權的人也能查看這些信息。

But there are also more powerful kinds of traffic analysis. Some attackers spy on multiple parts of the Internet and use sophisticated statistical techniques to track the communications patterns of many different organizations and individuals. Encryption does not help against these attackers, since it only hides the content of Internet traffic, not the headers.

而流量分析的手段還遠不止于此。有些攻擊者監聽著互聯網的多個部分，并利用一些復雜的技術來跟蹤許多不同機構或個人的通信規律。加密對于這種攻擊者來說束手無策，因為它只能幫你隱藏數據內容，而包頭部信息則赤裸裸地暴露在攻擊者面前。

本文為純翻譯，不帶有個人觀點。有不當的地方請指正。

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