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59 lines
2.0 KiB
Plaintext
59 lines
2.0 KiB
Plaintext
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Special Hostnames in Tor
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Nick Mathewson
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1. Overview
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Most of the time, Tor treats user-specified hostnames as opaque: When
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the user connects to www.torproject.org, Tor picks an exit node and uses
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that node to connect to "www.torproject.org". Some hostnames, however,
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can be used to override Tor's default behavior and circuit-building
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rules.
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These hostnames can be passed to Tor as the address part of a SOCKS4a or
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SOCKS5 request. If the application is connected to Tor using an IP-only
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method (such as SOCKS4, TransPort, or NATDPort), these hostnames can be
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substituted for certain IP addresses using the MapAddress configuration
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option or the MAPADDRESS control command.
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2. .exit
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SYNTAX: [hostname].[name-or-digest].exit
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[name-or-digest].exit
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Hostname is a valid hostname; [name-or-digest] is either the nickname of a
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Tor node or the hex-encoded digest of that node's public key.
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When Tor sees an address in this format, it uses the specified hostname as
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the exit node. If no "hostname" component is given, Tor defaults to the
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published IPv4 address of the exit node.
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It is valid to try to resolve hostnames, and in fact upon success Tor
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will cache an internal mapaddress of the form
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"www.google.com.foo.exit=64.233.161.99.foo.exit" to speed subsequent
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lookups.
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The .exit notation is disabled by default as of Tor 0.2.2.1-alpha, due
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to potential application-level attacks.
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EXAMPLES:
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www.example.com.exampletornode.exit
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Connect to www.example.com from the node called "exampletornode".
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exampletornode.exit
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Connect to the published IP address of "exampletornode" using
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"exampletornode" as the exit.
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3. .onion
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SYNTAX: [digest].onion
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The digest is the first eighty bits of a SHA1 hash of the identity key for
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a hidden service, encoded in base32.
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When Tor sees an address in this format, it tries to look up and connect to
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the specified hidden service. See rend-spec.txt for full details.
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