page_title: Tor (anonymity network)
section_title: Originating traffic
hierarchical_section_title: Tor (anonymity network) / Operation / Originating traffic
caption_attribution_description: English: A depiction of the traffic between some Tor replay nodes from the open source packet sniffing program EtherApe.
context_page_description: Tor is free and open-source software for enabling anonymous communication. The name derived from the acronym for the original software project name "The Onion Router". Tor directs Internet traffic through a free, worldwide, volunteer overlay network consisting of more than seven thousand relays to conceal a user's location and usage from anyone conducting network surveillance or traffic analysis. Using Tor makes it more difficult to trace Internet activity to the user: this includes "visits to Web sites, online posts, instant messages, and other communication forms". Tor's intended use is to protect the personal privacy of its users, as well as their freedom and ability to conduct confidential communication by keeping their Internet activities unmonitored.
  Tor does not prevent an online service from determining that it is being accessed through Tor. Tor protects a user's privacy, but does not hide the fact that someone is using Tor. Some websites restrict allowances through Tor. For example, Wikipedia blocks attempts by Tor users to edit articles unless special permission is sought.
context_section_description: A Tor user's SOCKS-aware applications can be configured to direct their network traffic through a Tor instance's SOCKS interface, which is listening on TCP port 9150 at localhost. Tor periodically creates virtual circuits through the Tor network through which it can multiplex and onion-route that traffic to its destination. Once inside a Tor network, the traffic is sent from router to router along the circuit, ultimately reaching an exit node at which point the cleartext packet is available and is forwarded on to its original destination. Viewed from the destination, the traffic appears to originate at the Tor exit node.
  Tor's application independence sets it apart from most other anonymity networks: it works at the Transmission Control Protocol (TCP) stream level. Applications whose traffic is commonly anonymized using Tor include Internet Relay Chat (IRC), instant messaging, and World Wide Web browsing.
caption: A visual depiction of the traffic between some Tor relay nodes from the open-source packet sniffing program EtherApe
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