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130 lines
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130 lines
4.7 KiB
Plaintext
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Glossary
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The Tor Project
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Note: This document aims to specify terms, notations or phrases related
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to Tor and The Tor Project.
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This glossary is not a design document; it is only a reference.
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0. Preliminaries
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
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NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
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"OPTIONAL" in this document are to be interpreted as described in
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RFC 2119.
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1.0 Commonly used Tor configuration terms
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ORPort - Onion Router Port
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DirPort - Directory Port
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2.0 Tor network components
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2.1 Relay, aka OR (onion router)
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2.1.1 Specific roles
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Exit relay: The final hop in an exit circuit before traffic leaves
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the Tor network to connect to external servers.
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Non-exit relay: Relays which send and receive traffic only to
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other Tor relays.
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Entry relay: The first hop in a Tor circuit. Can be either a guard
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relay or a bridge, with bridges taking precedant.
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Guard relay: Currently only used as entry relays. Guard relays
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are rotated more slowly to prevent enumeration attacks.
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Bridge: A relay intentionally not listed in the public Tor
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consensus, with the purpose of circumventing entities (such as
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governments or ISPs) seeking to block clients from using Tor.
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Currently, bridges are used only as entry relays.
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Directory cache: On bootstrap, clients will query a directory
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authority for the latest consensus. However, later consensus
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fetches can be made to directory caches, which can be any relay in
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the network.
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Rendezvous point: A relay connecting a client to a hidden service.
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Each party will build a three-hop circuit, meeting at the
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rendezvous point.
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2.2 Client, aka OP (onion proxy)
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2.3 Authorities:
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Directory Authority: Nine total in the Tor network, operated by
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trusted individuals. Directory authorities define and serve the
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consensus document, i.e, the "state of the network," which contains
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router statuses for all relays currently in the network. Directory
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authorities also serve server descriptors, extra info documents,
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microdescriptors, and the microdescriptor consensus,
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Bridge Authority: One total. Similar in responsibility to directory
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authorities, but for bridges.
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Fallback Directory Mirror: On bootstrap, a client will first attempt
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to fetch the consensus document from fallback directory mirrors,
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a relay selected for this role due to its stability and longevity
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on the network.
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2.4 Hidden Service:
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A hidden service is a server that will only accept incoming
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connections via the hidden service protocol. Connection
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initiators will not be able to learn the IP address of the hidden
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service, allowing the hidden service to receive incoming connections,
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serve content, etc, while preserving its location anonymity.
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2.5 Circuit:
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An established path through the network, where cryptographic keys
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are negotiated using the ntor protocol or TAP (Tor Authentication
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Protocol (deprecated) with each hop. Circuits can differ in length
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depending on their purpose. See also Leaky Pipe Topology.
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Origin Circuit -
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Exit Circuit: A circuit which connects clients to destinations
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outside the Tor network. For example, if a client wanted to visit
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duckduckgo.com, this connection would require an exit circuit.
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Internal Circuit: A circuit whose traffic never leaves the Tor
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network. For example, a client could connect to a hidden service via
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an internal circuit.
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2.6 Edge connection:
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2.7 Consensus: The state of the Tor network, published every hour,
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decided by a vote from the network's directory authorities. Clients
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fetch the consensus from directory authorities, fallback
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directories, or directory caches.
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2.8 Descriptor: Each descriptor represents information about one
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relay in the Tor network. The descriptor includes the relay's IP
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address, public key fingerprint, along with other data. Relays send
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descriptors to directory authorities, who will vote and publish a
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summary of them in the network consensus.
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3.0 Tor network protocols
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Link handshake
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Circuit handshake
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Hidden Service Protocol
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Directory Protocol
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4.0 General network definitions
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Leaky Pipe Topology: The ability for packets to be addressed to any
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hop in the path of a circuit. In Tor, the destination hop is
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determined by using the recognized field of relay cells.
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Stream: In the Tor network specifically, TCP streams are multiplexed
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over circuits.
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TLS connection: All pairwise connections in the Tor network are made
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over TLS.
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