tor/doc/tor.1.txt

// Copyright (c) The Tor Project, Inc.
// See LICENSE for licensing information
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TOR(1)
======

NAME
----
tor - The second-generation onion router


SYNOPSIS
--------
**tor** [__OPTION__ __value__]...

DESCRIPTION
-----------
__tor__ is a connection-oriented anonymizing communication
service. Users choose a source-routed path through a set of nodes, and
negotiate a "virtual circuit" through the network, in which each node
knows its predecessor and successor, but no others. Traffic flowing down
the circuit is unwrapped by a symmetric key at each node, which reveals
the downstream node. +

Basically __tor__ provides a distributed network of servers ("onion routers").
Users bounce their TCP streams -- web traffic, ftp, ssh, etc -- around the
routers, and recipients, observers, and even the routers themselves have
difficulty tracking the source of the stream.

OPTIONS
-------
**-h**, **-help**::
    Display a short help message and exit.

**-f** __FILE__::
    FILE contains further "option value" paris. (Default: @CONFDIR@/torrc)

**--hash-password**::
    Generates a hashed password for control port access.

**--list-fingerprint**::
    Generate your keys and output your nickname and fingerprint.

**--verify-config**::
    Verify the configuration file is valid.

**--nt-service**::
    **--service [install|remove|start|stop]** Manage the Tor Windows
    NT/2000/XP service. Current instructions can be found at
    https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#WinNTService

**--list-torrc-options**::
    List all valid options.

**--version**::
    Display Tor version and exit.

**--quiet**::
    Do not start Tor with a console log unless explicitly requested to do so.
    (By default, Tor starts out logging messages at level "notice" or higher to
    the console, until it has parsed its configuration.)

Other options can be specified either on the command-line (--option
    value), or in the configuration file (option value or option "value").
    Options are case-insensitive. C-style escaped characters are allowed inside
    quoted values.

**BandwidthRate** __N__ **bytes**|**KB**|**MB**|**GB**|**TB**::
    A token bucket limits the average incoming bandwidth usage on this node to
    the specified number of bytes per second, and the average outgoing
    bandwidth usage to that same value. (Default: 5 MB)

**BandwidthBurst** __N__ **bytes**|**KB**|**MB**|**GB**|**TB**::
    Limit the maximum token bucket size (also known as the burst) to the given
    number of bytes in each direction. (Default: 10 MB)

**MaxAdvertisedBandwidth** __N__ **bytes**|**KB**|**MB**|**GB**|**TB**::
    If set, we will not advertise more than this amount of bandwidth for our
    BandwidthRate. Server operators who want to reduce the number of clients
    who ask to build circuits through them (since this is proportional to
    advertised bandwidth rate) can thus reduce the CPU demands on their server
    without impacting network performance.

**RelayBandwidthRate** __N__ **bytes**|**KB**|**MB**|**GB**|**TB**::
    If defined, a separate token bucket limits the average incoming bandwidth
    usage for \_relayed traffic_ on this node to the specified number of bytes
    per second, and the average outgoing bandwidth usage to that same value.
    Relayed traffic currently is calculated to include answers to directory
    requests, but that may change in future versions. (Default: 0)

**RelayBandwidthBurst** __N__ **bytes**|**KB**|**MB**|**GB**|**TB**::
    Limit the maximum token bucket size (also known as the burst) for
    \_relayed traffic_ to the given number of bytes in each direction.
    (Default: 0)

**PerConnBWRate** __N__ **bytes**|**KB**|**MB**|**GB**|**TB**::
    If set, do separate rate limiting for each connection from a non-relay.
    You should never need to change this value, since a network-wide value is
    published in the consensus and your relay will use that value. (Default: 0)

**PerConnBWBurst** __N__ **bytes**|**KB**|**MB**|**GB**|**TB**::
    If set, do separate rate limiting for each connection from a non-relay.
    You should never need to change this value, since a network-wide value is
    published in the consensus and your relay will use that value. (Default: 0)

**ConLimit** __NUM__::
    The minimum number of file descriptors that must be available to the Tor
    process before it will start. Tor will ask the OS for as many file
    descriptors as the OS will allow (you can find this by "ulimit -H -n").
    If this number is less than ConnLimit, then Tor will refuse to start. +
 +
    You probably don't need to adjust this. It has no effect on Windows
    since that platform lacks getrlimit(). (Default: 1000)

**ConstrainedSockets** **0**|**1**::
    If set, Tor will tell the kernel to attempt to shrink the buffers for all
    sockets to the size specified in **ConstrainedSockSize**. This is useful for
    virtual servers and other environments where system level TCP buffers may
    be limited. If you're on a virtual server, and you encounter the "Error
    creating network socket: No buffer space available" message, you are
    likely experiencing this problem. +
 +
    The preferred solution is to have the admin increase the buffer pool for
    the host itself via /proc/sys/net/ipv4/tcp_mem or equivalent facility;
    this configuration option is a second-resort. +
 +
    The DirPort option should also not be used if TCP buffers are scarce. The
    cached directory requests consume additional sockets which exacerbates
    the problem. +
 +
    You should **not** enable this feature unless you encounter the "no buffer
    space available" issue. Reducing the TCP buffers affects window size for
    the TCP stream and will reduce throughput in proportion to round trip
    time on long paths. (Default: 0.)

**ConstrainedSockSize** __N__ **bytes**|**KB**::
    When **ConstrainedSockets** is enabled the receive and transmit buffers for
    all sockets will be set to this limit. Must be a value between 2048 and
    262144, in 1024 byte increments. Default of 8192 is recommended.

**ControlPort** __Port__::
    If set, Tor will accept connections on this port and allow those
    connections to control the Tor process using the Tor Control Protocol
    (described in control-spec.txt). Note: unless you also specify one of
    **HashedControlPassword** or **CookieAuthentication**, setting this option will
    cause Tor to allow any process on the local host to control it. This
    option is required for many Tor controllers; most use the value of 9051.

**ControlListenAddress** __IP__[:__PORT__]::
    Bind the controller listener to this address. If you specify a port, bind
    to this port rather than the one specified in ControlPort. We strongly
    recommend that you leave this alone unless you know what you're doing,
    since giving attackers access to your control listener is really
    dangerous. (Default: 127.0.0.1) This directive can be specified multiple
    times to bind to multiple addresses/ports.

**ControlSocket** __Path__::
    Like ControlPort, but listens on a Unix domain socket, rather than a TCP
    socket. (Unix and Unix-like systems only.)

**HashedControlPassword** __hashed_password__::
    Don't allow any connections on the control port except when the other
    process knows the password whose one-way hash is __hashed_password__. You
    can compute the hash of a password by running "tor --hash-password
    __password__". You can provide several acceptable passwords by using more
    than one HashedControlPassword line.

**CookieAuthentication** **0**|**1**::
    If this option is set to 1, don't allow any connections on the control port
    except when the connecting process knows the contents of a file named
    "control_auth_cookie", which Tor will create in its data directory. This
    authentication method should only be used on systems with good filesystem
    security. (Default: 0)

**CookieAuthFile** __Path__::
    If set, this option overrides the default location and file name
    for Tor's cookie file. (See CookieAuthentication above.)

**CookieAuthFileGroupReadable** **0**|**1**|__Groupname__::
    If this option is set to 0, don't allow the filesystem group to read the
    cookie file. If the option is set to 1, make the cookie file readable by
    the default GID. [Making the file readable by other groups is not yet
    implemented; let us know if you need this for some reason.] (Default: 0).

**DataDirectory** __DIR__::
    Store working data in DIR (Default: @LOCALSTATEDIR@/lib/tor)

**DirServer** [__nickname__] [**flags**] __address__:__port__ __fingerprint__::
    Use a nonstandard authoritative directory server at the provided address
    and port, with the specified key fingerprint. This option can be repeated
    many times, for multiple authoritative directory servers. Flags are
    separated by spaces, and determine what kind of an authority this directory
    is. By default, every authority is authoritative for current ("v2")-style
    directories, unless the "no-v2" flag is given. If the "v1" flags is
    provided, Tor will use this server as an authority for old-style (v1)
    directories as well. (Only directory mirrors care about this.) Tor will
    use this server as an authority for hidden service information if the "hs"
    flag is set, or if the "v1" flag is set and the "no-hs" flag is **not** set.
    Tor will use this authority as a bridge authoritative directory if the
    "bridge" flag is set. If a flag "orport=**port**" is given, Tor will use the
    given port when opening encrypted tunnels to the dirserver. Lastly, if a
    flag "v3ident=**fp**" is given, the dirserver is a v3 directory authority
    whose v3 long-term signing key has the fingerprint **fp**. +
 +
    If no **dirserver** line is given, Tor will use the default directory
    servers. NOTE: this option is intended for setting up a private Tor
    network with its own directory authorities. If you use it, you will be
    distinguishable from other users, because you won't believe the same
    authorities they do.

**AlternateDirAuthority** [__nickname__] [**flags**] __address__:__port__ __fingerprint__ +

**AlternateHSAuthority** [__nickname__] [**flags**] __address__:__port__ __fingerprint__ +

**AlternateBridgeAuthority** [__nickname__] [**flags**] __address__:__port__ __ fingerprint__::
    As DirServer, but replaces less of the default directory authorities. Using
    AlternateDirAuthority replaces the default Tor directory authorities, but
    leaves the hidden service authorities and bridge authorities in place.
    Similarly, Using AlternateHSAuthority replaces the default hidden service
    authorities, but not the directory or bridge authorities.

**DisableAllSwap** **0**|**1**::
    If set to 1, Tor will attempt to lock all current and future memory pages,
    so that memory cannot be paged out. Windows, OS X and Solaris are currently
    not supported. We believe that this feature works on modern Gnu/Linux
    distributions, and that it should work on *BSD systems (untested). This
    option requires that you start your Tor as root, and you should use the
    **User** option to properly reduce Tor's privileges. (Default: 0)

**FetchDirInfoEarly** **0**|**1**::
    If set to 1, Tor will always fetch directory information like other
    directory caches, even if you don't meet the normal criteria for fetching
    early. Normal users should leave it off. (Default: 0)

**FetchDirInfoExtraEarly** **0**|**1**::
    If set to 1, Tor will fetch directory information before other directory
    caches. It will attempt to download directory information closer to the
    start of the consensus period. Normal users should leave it off.
    (Default: 0)

**FetchHidServDescriptors** **0**|**1**::
    If set to 0, Tor will never fetch any hidden service descriptors from the
    rendezvous directories. This option is only useful if you're using a Tor
    controller that handles hidden service fetches for you. (Default: 1)

**FetchServerDescriptors** **0**|**1**::
    If set to 0, Tor will never fetch any network status summaries or server
    descriptors from the directory servers. This option is only useful if
    you're using a Tor controller that handles directory fetches for you.
    (Default: 1)

**FetchUselessDescriptors** **0**|**1**::
    If set to 1, Tor will fetch every non-obsolete descriptor from the
    authorities that it hears about. Otherwise, it will avoid fetching useless
    descriptors, for example for routers that are not running. This option is
    useful if you're using the contributed "exitlist" script to enumerate Tor
    nodes that exit to certain addresses. (Default: 0)

**HTTPProxy** __host__[:__port__]::
    Tor will make all its directory requests through this host:port (or host:80
    if port is not specified), rather than connecting directly to any directory
    servers.

**HTTPProxyAuthenticator** __username:password__::
    If defined, Tor will use this username:password for Basic HTTP proxy
    authentication, as in RFC 2617. This is currently the only form of HTTP
    proxy authentication that Tor supports; feel free to submit a patch if you
    want it to support others.

**HTTPSProxy** __host__[:__port__]::
    Tor will make all its OR (SSL) connections through this host:port (or
    host:443 if port is not specified), via HTTP CONNECT rather than connecting
    directly to servers. You may want to set **FascistFirewall** to restrict
    the set of ports you might try to connect to, if your HTTPS proxy only
    allows connecting to certain ports.

**HTTPSProxyAuthenticator** __username:password__::
    If defined, Tor will use this username:password for Basic HTTPS proxy
    authentication, as in RFC 2617. This is currently the only form of HTTPS
    proxy authentication that Tor supports; feel free to submit a patch if you
    want it to support others.

**Socks4Proxy** __host__[:__port__]::
    Tor will make all OR connections through the SOCKS 4 proxy at host:port
    (or host:1080 if port is not specified).

**Socks5Proxy** __host__[:__port__]::
    Tor will make all OR connections through the SOCKS 5 proxy at host:port
    (or host:1080 if port is not specified).

**Socks5ProxyUsername** __username__ +

**Socks5ProxyPassword** __password__::
    If defined, authenticate to the SOCKS 5 server using username and password
    in accordance to RFC 1929. Both username and password must be between 1 and
    255 characters.

**KeepalivePeriod** __NUM__::
    To keep firewalls from expiring connections, send a padding keepalive cell
    every NUM seconds on open connections that are in use. If the connection
    has no open circuits, it will instead be closed after NUM seconds of
    idleness. (Default: 5 minutes)

**Log** __minSeverity__[-__maxSeverity__] **stderr**|**stdout**|**syslog**::
    Send all messages between __minSeverity__ and __maxSeverity__ to the standard
    output stream, the standard error stream, or to the system log. (The
    "syslog" value is only supported on Unix.) Recognized severity levels are
    debug, info, notice, warn, and err. We advise using "notice" in most cases,
    since anything more verbose may provide sensitive information to an
    attacker who obtains the logs. If only one severity level is given, all
    messages of that level or higher will be sent to the listed destination.

**Log** __minSeverity__[-__maxSeverity__] **file** __FILENAME__::
    As above, but send log messages to the listed filename. The
    "Log" option may appear more than once in a configuration file.
    Messages are sent to all the logs that match their severity
    level.

**OutboundBindAddress** __IP__::
    Make all outbound connections originate from the IP address specified. This
    is only useful when you have multiple network interfaces, and you want all
    of Tor's outgoing connections to use a single one.

**PidFile** __FILE__::
    On startup, write our PID to FILE. On clean shutdown, remove
    FILE.

**ProtocolWarnings** **0**|**1**::
    If 1, Tor will log with severity \'warn' various cases of other parties not
    following the Tor specification. Otherwise, they are logged with severity
    \'info'. (Default: 0)

**RunAsDaemon** **0**|**1**::
    If 1, Tor forks and daemonizes to the background. This option has no effect
    on Windows; instead you should use the --service command-line option.
    (Default: 0)


**SafeLogging** **0**|**1**|**relay**::
    Tor can scrub potentially sensitive strings from log messages (e.g.
    addresses) by replacing them with the string [scrubbed]. This way logs can
    still be useful, but they don't leave behind personally identifying
    information about what sites a user might have visited. +
 +
    If this option is set to 0, Tor will not perform any scrubbing, if it is
    set to 1, all potentially sensitive strings are replaced. If it is set to
    relay, all log messages generated when acting as a relay are sanitized, but
    all messages generated when acting as a client are not. (Default: 1)

**User** __UID__::
    On startup, setuid to this user and setgid to their primary group.

**HardwareAccel** **0**|**1**::
    If non-zero, try to use built-in (static) crypto hardware acceleration when
    available. (Default: 0)

**AccelName** __NAME__::
    When using OpenSSL hardware crypto acceleration attempt to load the dynamic
    engine of this name. This must be used for any dynamic hardware engine.
    Names can be verified with the openssl engine command.

**AccelDir** __DIR__::
    Specify this option if using dynamic hardware acceleration and the engine
    implementation library resides somewhere other than the OpenSSL default.

**AvoidDiskWrites** **0**|**1**::
    If non-zero, try to write to disk less frequently than we would otherwise.
    This is useful when running on flash memory or other media that support
    only a limited number of writes. (Default: 0)

**TunnelDirConns** **0**|**1**::
    If non-zero, when a directory server we contact supports it, we will build
    a one-hop circuit and make an encrypted connection via its ORPort.
    (Default: 1)

**PreferTunneledDirConns** **0**|**1**::
    If non-zero, we will avoid directory servers that don't support tunneled
    directory connections, when possible. (Default: 1)

**CircuitPriorityHalflife** __NUM1__::
    If this value is set, we override the default algorithm for choosing which
    circuit's cell to deliver or relay next. When the value is 0, we
    round-robin between the active circuits on a connection, delivering one
    cell from each in turn. When the value is positive, we prefer delivering
    cells from whichever connection has the lowest weighted cell count, where
    cells are weighted exponentially according to the supplied
    CircuitPriorityHalflife value (in seconds). If this option is not set at
    all, we use the behavior recommended in the current consensus
    networkstatus. This is an advanced option; you generally shouldn't have
    to mess with it. (Default: not set.)

CLIENT OPTIONS
--------------

The following options are useful only for clients (that is, if
**SocksPort** is non-zero):

**AllowInvalidNodes** **entry**|**exit**|**middle**|**introduction**|**rendezvous**|**...**::
    If some Tor servers are obviously not working right, the directory
    authorities can manually mark them as invalid, meaning that it's not
    recommended you use them for entry or exit positions in your circuits. You
    can opt to use them in some circuit positions, though. The default is
    "middle,rendezvous", and other choices are not advised.

**ExcludeSingleHopRelays** **0**|**1**::
    This option controls whether circuits built by Tor will include relays with
    the AllowSingleHopExits flag set to true. If ExcludeSingleHopRelays is set
    to 0, these relays will be included. Note that these relays might be at
    higher risk of being seized or observed, so they are not normally included.
    (Default: 1)

**Bridge** __IP__:__ORPort__ [fingerprint]::
    When set along with UseBridges, instructs Tor to use the relay at
    "IP:ORPort" as a "bridge" relaying into the Tor network. If "fingerprint"
    is provided (using the same format as for DirServer), we will verify that
    the relay running at that location has the right fingerprint. We also use
    fingerprint to look up the bridge descriptor at the bridge authority, if
    it's provided and if UpdateBridgesFromAuthority is set too.

**CircuitBuildTimeout** __NUM__::
    Try for at most NUM seconds when building circuits. If the circuit isn't
    open in that time, give up on it. (Default: 1 minute.)

**CircuitIdleTimeout** __NUM__::
    If we have kept a clean (never used) circuit around for NUM seconds, then
    close it. This way when the Tor client is entirely idle, it can expire all
    of its circuits, and then expire its TLS connections. Also, if we end up
    making a circuit that is not useful for exiting any of the requests we're
    receiving, it won't forever take up a slot in the circuit list. (Default: 1
    hour.)

**CircuitStreamTimeout** __NUM__::
    If non-zero, this option overrides our internal timeout schedule for how
    many seconds until we detach a stream from a circuit and try a new circuit.
    If your network is particularly slow, you might want to set this to a
    number like 60. (Default: 0)

**ClientOnly** **0**|**1**::
    If set to 1, Tor will under no circumstances run as a server or serve
    directory requests. The default is to run as a client unless ORPort is
    configured. (Usually, you don't need to set this; Tor is pretty smart at
    figuring out whether you are reliable and high-bandwidth enough to be a
    useful server.) (Default: 0)

**ExcludeNodes** __node__,__node__,__...__::
    A list of identity fingerprints, nicknames, country codes and address
    patterns of nodes to never use when building a circuit. (Example:
    ExcludeNodes SlowServer, $    EFFFFFFFFFFFFFFF, \{cc}, 255.254.0.0/8)

**ExcludeExitNodes** __node__,__node__,__...__::
    A list of identity fingerprints, nicknames, country codes and address
    patterns of nodes to never use when picking an exit node. Note that any
    node listed in ExcludeNodes is automatically considered to be part of this
    list.

**EntryNodes** __node__,__node__,__...__::
    A list of identity fingerprints, nicknames, country codes and address
    patterns of nodes to use for the first hop in normal circuits. These are
    treated only as preferences unless StrictNodes (see below) is also set.

**ExitNodes** __node__,__node__,__...__::
    A list of identity fingerprints, nicknames, country codes and address
    patterns of nodes to use for the last hop in normal exit circuits. These
    are treated only as preferences unless StrictNodes (see below) is also set.

**StrictNodes** **0**|**1**::
    If 1 and EntryNodes config option is set, Tor will never use any nodes
    besides those listed in EntryNodes for the first hop of a normal circuit.
    If 1 and ExitNodes config option is set, Tor will never use any nodes
    besides those listed in ExitNodes for the last hop of a normal exit
    circuit. Note that Tor might still use these nodes for non-exit circuits
    such as one-hop directory fetches or hidden service support circuits.

**FascistFirewall** **0**|**1**::
    If 1, Tor will only create outgoing connections to ORs running on ports
    that your firewall allows (defaults to 80 and 443; see **FirewallPorts**).
    This will allow you to run Tor as a client behind a firewall with
    restrictive policies, but will not allow you to run as a server behind such
    a firewall. If you prefer more fine-grained control, use
    ReachableAddresses instead.

**FirewallPorts** __PORTS__::
    A list of ports that your firewall allows you to connect to. Only used when
    **FascistFirewall** is set. This option is deprecated; use ReachableAddresses
    instead. (Default: 80, 443)

**HidServAuth** __onion-address__ __auth-cookie__ [__service-name__]::
    Client authorization for a hidden service. Valid onion addresses contain 16
    characters in a-z2-7 plus ".onion", and valid auth cookies contain 22
    characters in A-Za-z0-9+/. The service name is only used for internal
    purposes, e.g., for Tor controllers. This option may be used multiple times
    for different hidden services. If a hidden service uses authorization and
    this option is not set, the hidden service is not accessible. Hidden
    services can be configured to require authorization using the 
    **HiddenServiceAuthorizeClient** option.

**ReachableAddresses** __ADDR__[/__MASK__][:__PORT__]...::
    A comma-separated list of IP addresses and ports that your firewall allows
    you to connect to. The format is as for the addresses in ExitPolicy, except
    that "accept" is understood unless "reject" is explicitly provided. For
    example, \'ReachableAddresses 99.0.0.0/8, reject 18.0.0.0/8:80, accept
    \*:80' means that your firewall allows connections to everything inside net
    99, rejects port 80 connections to net 18, and accepts connections to port
    80 otherwise. (Default: \'accept \*:*'.)

**ReachableDirAddresses** __ADDR__[/__MASK__][:__PORT__]...::
    Like **ReachableAddresses**, a list of addresses and ports. Tor will obey
    these restrictions when fetching directory information, using standard HTTP
    GET requests. If not set explicitly then the value of
    **ReachableAddresses** is used. If **HTTPProxy** is set then these
    connections will go through that proxy.

**ReachableORAddresses** __ADDR__[/__MASK__][:__PORT__]...::
    Like **ReachableAddresses**, a list of addresses and ports. Tor will obey
    these restrictions when connecting to Onion Routers, using TLS/SSL. If not
    set explicitly then the value of **ReachableAddresses** is used. If
    **HTTPSProxy** is set then these connections will go through that proxy. +
 +
    The separation between **ReachableORAddresses** and
    **ReachableDirAddresses** is only interesting when you are connecting
    through proxies (see **HTTPProxy** and **HTTPSProxy**). Most proxies limit
    TLS connections (which Tor uses to connect to Onion Routers) to port 443,
    and some limit HTTP GET requests (which Tor uses for fetching directory
    information) to port 80.

**LongLivedPorts** __PORTS__::
    A list of ports for services that tend to have long-running connections
    (e.g. chat and interactive shells). Circuits for streams that use these
    ports will contain only high-uptime nodes, to reduce the chance that a node
    will go down before the stream is finished. (Default: 21, 22, 706, 1863,
    5050, 5190, 5222, 5223, 6667, 6697, 8300)

**MapAddress** __address__ __newaddress__::
    When a request for address arrives to Tor, it will rewrite it to newaddress
    before processing it. For example, if you always want connections to
    www.indymedia.org to exit via __torserver__ (where __torserver__ is the
    nickname of the server), use "MapAddress www.indymedia.org
    www.indymedia.org.torserver.exit".

**NewCircuitPeriod** __NUM__::
    Every NUM seconds consider whether to build a new circuit. (Default: 30
    seconds)

**MaxCircuitDirtiness** __NUM__::
    Feel free to reuse a circuit that was first used at most NUM seconds ago,
    but never attach a new stream to a circuit that is too old. (Default: 10
    minutes)

**NodeFamily** __node__,__node__,__...__::
    The Tor servers, defined by their identity fingerprints or nicknames,
    constitute a "family" of similar or co-administered servers, so never use
    any two of them in the same circuit. Defining a NodeFamily is only needed
    when a server doesn't list the family itself (with MyFamily). This option
    can be used multiple times.

**EnforceDistinctSubnets** **0**|**1**::
    If 1, Tor will not put two servers whose IP addresses are "too close" on
    the same circuit. Currently, two addresses are "too close" if they lie in
    the same /16 range. (Default: 1)

**SocksPort** __PORT__::
    Advertise this port to listen for connections from Socks-speaking
    applications. Set this to 0 if you don't want to allow application
    connections. (Default: 9050)

**SocksListenAddress** __IP__[:__PORT__]::
    Bind to this address to listen for connections from Socks-speaking
    applications. (Default: 127.0.0.1) You can also specify a port (e.g.
    192.168.0.1:9100). This directive can be specified multiple times to bind
    to multiple addresses/ports.

**SocksPolicy** __policy__,__policy__,__...__::
    Set an entrance policy for this server, to limit who can connect to the
    SocksPort and DNSPort ports. The policies have the same form as exit
    policies below.

**SocksTimeout** __NUM__::
    Let a socks connection wait NUM seconds handshaking, and NUM seconds
    unattached waiting for an appropriate circuit, before we fail it. (Default:
    2 minutes.)

**TrackHostExits** __host__,__.domain__,__...__::
    For each value in the comma separated list, Tor will track recent
    connections to hosts that match this value and attempt to reuse the same
    exit node for each. If the value is prepended with a \'.\', it is treated as
    matching an entire domain. If one of the values is just a \'.', it means
    match everything. This option is useful if you frequently connect to sites
    that will expire all your authentication cookies (i.e. log you out) if
    your IP address changes. Note that this option does have the disadvantage
    of making it more clear that a given history is associated with a single
    user. However, most people who would wish to observe this will observe it
    through cookies or other protocol-specific means anyhow.

**TrackHostExitsExpire** __NUM__::
    Since exit servers go up and down, it is desirable to expire the
    association between host and exit server after NUM seconds. The default is
    1800 seconds (30 minutes).

**UpdateBridgesFromAuthority** **0**|**1**::
    When set (along with UseBridges), Tor will try to fetch bridge descriptors
    from the configured bridge authorities when feasible. It will fall back to
    a direct request if the authority responds with a 404. (Default: 0)

**UseBridges** **0**|**1**::
    When set, Tor will fetch descriptors for each bridge listed in the "Bridge"
    config lines, and use these relays as both entry guards and directory
    guards. (Default: 0)

**UseEntryGuards** **0**|**1**::
    If this option is set to 1, we pick a few long-term entry servers, and try
    to stick with them. This is desirable because constantly changing servers
    increases the odds that an adversary who owns some servers will observe a
    fraction of your paths. (Defaults to 1.)

**NumEntryGuards** __NUM__::
    If UseEntryGuards is set to 1, we will try to pick a total of NUM routers
    as long-term entries for our circuits. (Defaults to 3.)

**SafeSocks** **0**|**1**::
    When this option is enabled, Tor will reject application connections that
    use unsafe variants of the socks protocol -- ones that only provide an IP
    address, meaning the application is doing a DNS resolve first.
    Specifically, these are socks4 and socks5 when not doing remote DNS.
    (Defaults to 0.)

**TestSocks** **0**|**1**::
    When this option is enabled, Tor will make a notice-level log entry for
    each connection to the Socks port indicating whether the request used a
    safe socks protocol or an unsafe one (see above entry on SafeSocks). This
    helps to determine whether an application using Tor is possibly leaking
    DNS requests. (Default: 0)

**VirtualAddrNetwork** __Address__/__bits__::
    When a controller asks for a virtual (unused) address with the MAPADDRESS
    command, Tor picks an unassigned address from this range. (Default:
    127.192.0.0/10) +
 +
    When providing proxy server service to a network of computers using a tool
    like dns-proxy-tor, change this address to "10.192.0.0/10" or
    "172.16.0.0/12". The default **VirtualAddrNetwork** address range on a
    properly configured machine will route to the loopback interface. For
    local use, no change to the default VirtualAddrNetwork setting is needed.

**AllowNonRFC953Hostnames** **0**|**1**::
    When this option is disabled, Tor blocks hostnames containing illegal
    characters (like @ and :) rather than sending them to an exit node to be
    resolved. This helps trap accidental attempts to resolve URLs and so on.
    (Default: 0)

**AllowDotExit** **0**|**1**::
    If enabled, we convert "www.google.com.foo.exit" addresses on the
    SocksPort/TransPort/NatdPort into "www.google.com" addresses that exit from
    the node "foo". Disabled by default since attacking websites and exit
    relays can use it to manipulate your path selection. (Default: 0)

**FastFirstHopPK** **0**|**1**::
    When this option is disabled, Tor uses the public key step for the first
    hop of creating circuits. Skipping it is generally safe since we have
    already used TLS to authenticate the relay and to establish forward-secure
    keys. Turning this option off makes circuit building slower. +
 +
    Note that Tor will always use the public key step for the first hop if it's
    operating as a relay, and it will never use the public key step if it
    doesn't yet know the onion key of the first hop. (Default: 1)

**TransPort** __PORT__::
    If non-zero, enables transparent proxy support on __PORT__ (by convention,
    9040). Requires OS support for transparent proxies, such as BSDs' pf or
    Linux's IPTables. If you're planning to use Tor as a transparent proxy for
    a network, you'll want to examine and change VirtualAddrNetwork from the
    default setting. You'll also want to set the TransListenAddress option for
    the network you'd like to proxy. (Default: 0).

**TransListenAddress** __IP__[:__PORT__]::
    Bind to this address to listen for transparent proxy connections. (Default:
    127.0.0.1). This is useful for exporting a transparent proxy server to an
    entire network.

**NATDPort** __PORT__::
    Allow old versions of ipfw (as included in old versions of FreeBSD, etc.)
    to send connections through Tor using the NATD protocol. This option is
    only for people who cannot use TransPort.

**NATDListenAddress** __IP__[:__PORT__]::
    Bind to this address to listen for NATD connections. (Default: 127.0.0.1).

**AutomapHostsOnResolve** **0**|**1**::
    When this option is enabled, and we get a request to resolve an address
    that ends with one of the suffixes in **AutomapHostsSuffixes**, we map an
    unused virtual address to that address, and return the new virtual address. 
    This is handy for making ".onion" addresses work with applications that
    resolve an address and then connect to it. (Default: 0).

**AutomapHostsSuffixes** __SUFFIX__,__SUFFIX__,__...__::
    A comma-separated list of suffixes to use with **AutomapHostsOnResolve**.
    The "." suffix is equivalent to "all addresses." (Default: .exit,.onion).

**DNSPort** __PORT__::
    If non-zero, Tor listens for UDP DNS requests on this port and resolves
    them anonymously. (Default: 0).

**DNSListenAddress** __IP__[:__PORT__]::
    Bind to this address to listen for DNS connections. (Default: 127.0.0.1).

**ClientDNSRejectInternalAddresses** **0**|**1**::
    If true, Tor does not believe any anonymously retrieved DNS answer that
    tells it that an address resolves to an internal address (like 127.0.0.1 or
    192.168.0.1). This option prevents certain browser-based attacks; don't
    turn it off unless you know what you're doing. (Default: 1).

**DownloadExtraInfo** **0**|**1**::
    If true, Tor downloads and caches "extra-info" documents. These documents
    contain information about servers other than the information in their
    regular router descriptors. Tor does not use this information for anything
    itself; to save bandwidth, leave this option turned off. (Default: 0).

**FallbackNetworkstatusFile** __FILENAME__::
    If Tor doesn't have a cached networkstatus file, it starts out using this
    one instead. Even if this file is out of date, Tor can still use it to
    learn about directory mirrors, so it doesn't need to put load on the
    authorities. (Default: None).

**WarnPlaintextPorts** __port__,__port__,__...__::
    Tells Tor to issue a warnings whenever the user tries to make an anonymous
    connection to one of these ports. This option is designed to alert users
    to services that risk sending passwords in the clear. (Default:
    23,109,110,143).

**RejectPlaintextPorts** __port__,__port__,__...__::
    Like WarnPlaintextPorts, but instead of warning about risky port uses, Tor
    will instead refuse to make the connection. (Default: None).

SERVER OPTIONS
--------------

The following options are useful only for servers (that is, if ORPort
is non-zero):

**Address** __address__::
    The IP address or fully qualified domain name of this server (e.g.
    moria.mit.edu). You can leave this unset, and Tor will guess your IP
    address.

**AllowSingleHopExits** **0**|**1**::
    This option controls whether clients can use this server as a single hop
    proxy. If set to 1, clients can use this server as an exit even if it is
    the only hop in the circuit. (Default: 0)

**AssumeReachable** **0**|**1**::
    This option is used when bootstrapping a new Tor network. If set to 1,
    don't do self-reachability testing; just upload your server descriptor
    immediately. If **AuthoritativeDirectory** is also set, this option
    instructs the dirserver to bypass remote reachability testing too and list
    all connected servers as running.

**BridgeRelay** **0**|**1**::
    Sets the relay to act as a "bridge" with respect to relaying connections
    from bridge users to the Tor network. Mainly it influences how the relay
    will cache and serve directory information. Usually used in combination
    with PublishServerDescriptor.

**ContactInfo** __email_address__::
    Administrative contact information for server. This line might get picked
    up by spam harvesters, so you may want to obscure the fact that it's an
    email address.

**ExitPolicy** __policy__,__policy__,__...__::
    Set an exit policy for this server. Each policy is of the form
    "**accept**|**reject** __ADDR__[/__MASK__][:__PORT__]". If /__MASK__ is
    omitted then this policy just applies to the host given. Instead of giving
    a host or network you can also use "\*" to denote the universe (0.0.0.0/0).
    __PORT__ can be a single port number, an interval of ports
    "__FROM_PORT__-__TO_PORT__", or "\*". If __PORT__ is omitted, that means
    "\*". +
 +
    For example, "accept 18.7.22.69:\*,reject 18.0.0.0/8:\*,accept \*:\*" would
    reject any traffic destined for MIT except for web.mit.edu, and accept
    anything else. +
 +
    To specify all internal and link-local networks (including 0.0.0.0/8,
    169.254.0.0/16,    127.0.0.0/8,    192.168.0.0/16, 10.0.0.0/8, and
    172.16.0.0/12), you can use the "private" alias instead of an address.
    These addresses are rejected by default (at the beginning of your exit
    policy), along with your public IP address, unless you set the
    ExitPolicyRejectPrivate config option to 0. For example, once you've done
    that, you could allow HTTP to 127.0.0.1 and block all other connections to
    internal networks with "accept 127.0.0.1:80,reject private:\*", though that
    may also allow connections to your own computer that are addressed to its
    public (external) IP address. See RFC 1918 and RFC 3330 for more details
    about internal and reserved IP address space. +
 +
    This directive can be specified multiple times so you don't have to put it
    all on one line. +
 +
    Policies are considered first to last, and the first match wins. If you
    want to \_replace_ the default exit policy, end your exit policy with
    either a reject \*:* or an accept \*:*. Otherwise, you're \_augmenting_
    (prepending to) the default exit policy. The default exit policy is: +

       reject *:25
       reject *:119
       reject *:135-139
       reject *:445
       reject *:563
       reject *:1214
       reject *:4661-4666
       reject *:6346-6429
       reject *:6699
       reject *:6881-6999
       accept *:*

**ExitPolicyRejectPrivate** **0**|**1**::
    Reject all private (local) networks, along with your own public IP address,
    at the beginning of your exit policy. See above entry on ExitPolicy.
    (Default: 1)

**MaxOnionsPending** __NUM__::
    If you have more than this number of onionskins queued for decrypt, reject
    new ones. (Default: 100)

**MyFamily** __node__,__node__,__...__::
    Declare that this Tor server is controlled or administered by a group or
    organization identical or similar to that of the other servers, defined by
    their identity fingerprints or nicknames. When two servers both declare
    that they are in the same \'family', Tor clients will not use them in the
    same circuit. (Each server only needs to list the other servers in its
    family; it doesn't need to list itself, but it won't hurt.)

**Nickname** __name__::
    Set the server's nickname to \'name'. Nicknames must be between 1 and 19
    characters inclusive, and must contain only the characters [a-zA-Z0-9].

**NumCPUs** __num__::
    How many processes to use at once for decrypting onionskins. (Default: 1)

**ORPort** __PORT__::
    Advertise this port to listen for connections from Tor clients and servers.

**ORListenAddress** __IP__[:__PORT__]::
    Bind to this IP address to listen for connections from Tor clients and
    servers. If you specify a port, bind to this port rather than the one
    specified in ORPort. (Default: 0.0.0.0) This directive can be specified
    multiple times to bind to multiple addresses/ports.

**PublishServerDescriptor** **0**|**1**|**v1**|**v2**|**v3**|**bridge**|**hidserv**,**...**::
    This option is only considered if you have an ORPort defined. You can
    choose multiple arguments, separated by commas.
 +
    If set to 0, Tor will act as a server but it will not publish its
    descriptor to the directory authorities. (This is useful if you're testing
    out your server, or if you're using a Tor controller that handles directory
    publishing for you.) Otherwise, Tor will publish its descriptor to all
    directory authorities of the type(s) specified. The value "1" is the
    default, which means "publish to the appropriate authorities".

**ShutdownWaitLength** __NUM__::
    When we get a SIGINT and we're a server, we begin shutting down:
    we close listeners and start refusing new circuits. After **NUM**
    seconds, we exit. If we get a second SIGINT, we exit immedi-
    ately. (Default: 30 seconds)


**AccountingMax** __N__ **bytes**|**KB**|**MB**|**GB**|**TB**::
    Never send more than the specified number of bytes in a given accounting
    period, or receive more than that number in the period. For example, with
    AccountingMax set to 1 GB, a server could send 900 MB and receive 800 MB
    and continue running. It will only hibernate once one of the two reaches 1
    GB. When the number of bytes is exhausted, Tor will hibernate until some
    time in the next accounting period. To prevent all servers from waking at
    the same time, Tor will also wait until a random point in each period
    before waking up. If you have bandwidth cost issues, enabling hibernation
    is preferable to setting a low bandwidth, since it provides users with a
    collection of fast servers that are up some of the time, which is more
    useful than a set of slow servers that are always "available".

**AccountingStart** **day**|**week**|**month** [__day__] __HH:MM__::
    Specify how long accounting periods last. If **month** is given, each
    accounting period runs from the time __HH:MM__ on the __dayth__ day of one
    month to the same day and time of the next. (The day must be between 1 and
    28.) If **week** is given, each accounting period runs from the time __HH:MM__
    of the __dayth__ day of one week to the same day and time of the next week,
    with Monday as day 1 and Sunday as day 7. If **day** is given, each
    accounting period runs from the time __HH:MM__ each day to the same time on
    the next day. All times are local, and given in 24-hour time. (Defaults to
    "month 1 0:00".)

**ServerDNSResolvConfFile** __filename__::
    Overrides the default DNS configuration with the configuration in
    __filename__. The file format is the same as the standard Unix
    "**resolv.conf**" file (7). This option, like all other ServerDNS options,
    only affects name lookups that your server does on behalf of clients.
    (Defaults to use the system DNS configuration.)

**ServerDNSAllowBrokenConfig** **0**|**1**::
    If this option is false, Tor exits immediately if there are problems
    parsing the system DNS configuration or connecting to nameservers.
    Otherwise, Tor continues to periodically retry the system nameservers until
    it eventually succeeds. (Defaults to "1".)

**ServerDNSSearchDomains** **0**|**1**::
    If set to 1, then we will search for addresses in the local search domain.
    For example, if this system is configured to believe it is in
    "example.com", and a client tries to connect to "www", the client will be
    connected to "www.example.com". This option only affects name lookups that
    your server does on behalf of clients. (Defaults to "0".)

**ServerDNSDetectHijacking** **0**|**1**::
    When this option is set to 1, we will test periodically to determine
    whether our local nameservers have been configured to hijack failing DNS
    requests (usually to an advertising site). If they are, we will attempt to
    correct this. This option only affects name lookups that your server does
    on behalf of clients. (Defaults to "1".)

**ServerDNSTestAddresses** __address__,__address__,__...__::
    When we're detecting DNS hijacking, make sure that these __valid__ addresses
    aren't getting redirected. If they are, then our DNS is completely useless,
    and we'll reset our exit policy to "reject *:*". This option only affects
    name lookups that your server does on behalf of clients. (Defaults to
    "www.google.com, www.mit.edu, www.yahoo.com, www.slashdot.org".)

**ServerDNSAllowNonRFC953Hostnames** **0**|**1**::
    When this option is disabled, Tor does not try to resolve hostnames
    containing illegal characters (like @ and :) rather than sending them to an
    exit node to be resolved. This helps trap accidental attempts to resolve
    URLs and so on. This option only affects name lookups that your server does
    on behalf of clients. (Default: 0)

**BridgeRecordUsageByCountry** **0**|**1**::
    When this option is enabled and BridgeRelay is also enabled, and we have
    GeoIP data, Tor keeps a keep a per-country count of how many client
    addresses have contacted it so that it can help the bridge authority guess
    which countries have blocked access to it. (Default: 1)

**ServerDNSRandomizeCase** **0**|**1**::
    When this option is set, Tor sets the case of each character randomly in
    outgoing DNS requests, and makes sure that the case matches in DNS replies.
    This so-called "0x20 hack" helps resist some types of DNS poisoning attack.
    For more information, see "Increased DNS Forgery Resistance through
    0x20-Bit Encoding". This option only affects name lookups that your server
    does on behalf of clients. (Default: 1)

**GeoIPFile** __filename__::
    A filename containing GeoIP data, for use with BridgeRecordUsageByCountry.

**CellStatistics** **0**|**1**::
    When this option is enabled, Tor writes statistics on the mean time that
    cells spend in circuit queues to disk every 24 hours. Cannot be changed
    while Tor is running. (Default: 0)

**DirReqStatistics** **0**|**1**::
    When this option is enabled, Tor writes statistics on the number and
    response time of network status requests to disk every 24 hours. Cannot be
    changed while Tor is running. (Default: 0)

**EntryStatistics** **0**|**1**::
    When this option is enabled, Tor writes statistics on the number of
    directly connecting clients to disk every 24 hours. Cannot be changed while
    Tor is running. (Default: 0)

**ExitPortStatistics** **0**|**1**::
    When this option is enabled, Tor writes statistics on the number of relayed
    bytes and opened stream per exit port to disk every 24 hours. Cannot be
    changed while Tor is running. (Default: 0)

**ExtraInfoStatistics** **0**|**1**::
    When this option is enabled, Tor includes previously gathered statistics in
    its extra-info documents that it uploads to the directory authorities.
    (Default: 0)

DIRECTORY SERVER OPTIONS
------------------------

The following options are useful only for directory servers (that is,
if DirPort is non-zero):

**AuthoritativeDirectory** **0**|**1**::
    When this option is set to 1, Tor operates as an authoritative directory
    server. Instead of caching the directory, it generates its own list of
    good servers, signs it, and sends that to the clients. Unless the clients
    already have you listed as a trusted directory, you probably do not want
    to set this option. Please coordinate with the other admins at
    tor-ops@freehaven.net if you think you should be a directory.

**DirPortFrontPage** __FILENAME__::
    When this option is set, it takes an HTML file and publishes it as "/" on
    the DirPort. Now relay operators can provide a disclaimer without needing
    to set up a separate webserver. There's a sample disclaimer in
    contrib/tor-exit-notice.html.

**V1AuthoritativeDirectory** **0**|**1**::
    When this option is set in addition to **AuthoritativeDirectory**, Tor
    generates version 1 directory and running-routers documents (for legacy
    Tor clients up to 0.1.0.x).

**V2AuthoritativeDirectory** **0**|**1**::
    When this option is set in addition to **AuthoritativeDirectory**, Tor
    generates version 2 network statuses and serves descriptors, etc as
    described in doc/spec/dir-spec-v2.txt (for Tor clients and servers running
    0.1.1.x and 0.1.2.x).

**V3AuthoritativeDirectory** **0**|**1**::
    When this option is set in addition to **AuthoritativeDirectory**, Tor
    generates version 3 network statuses and serves descriptors, etc as
    described in doc/spec/dir-spec.txt (for Tor clients and servers running at
    least 0.2.0.x).

**VersioningAuthoritativeDirectory** **0**|**1**::
    When this option is set to 1, Tor adds information on which versions of
    Tor are still believed safe for use to the published directory. Each
    version 1 authority is automatically a versioning authority; version 2
    authorities provide this service optionally. See **RecommendedVersions**,
    **RecommendedClientVersions**, and **RecommendedServerVersions**.

**NamingAuthoritativeDirectory** **0**|**1**::
    When this option is set to 1, then the server advertises that it has
    opinions about nickname-to-fingerprint bindings. It will include these
    opinions in its published network-status pages, by listing servers with
    the flag "Named" if a correct binding between that nickname and fingerprint
    has been registered with the dirserver. Naming dirservers will refuse to
    accept or publish descriptors that contradict a registered binding. See
    **approved-routers** in the **FILES** section below.

**HSAuthoritativeDir** **0**|**1**::
    When this option is set in addition to **AuthoritativeDirectory**, Tor also
    accepts and serves hidden service descriptors. (Default: 0)

**HidServDirectoryV2** **0**|**1**::
    When this option is set, Tor accepts and serves v2 hidden service
    descriptors. Setting DirPort is not required for this, because clients
    connect via the ORPort by default. (Default: 1)

**BridgeAuthoritativeDir** **0**|**1**::
    When this option is set in addition to **AuthoritativeDirectory**, Tor
    accepts and serves router descriptors, but it caches and serves the main
    networkstatus documents rather than generating its own. (Default: 0)

**MinUptimeHidServDirectoryV2** __N__ **seconds**|**minutes**|**hours**|**days**|**weeks**::
    Minimum uptime of a v2 hidden service directory to be accepted as such by
    authoritative directories. (Default: 24 hours)

**DirPort** __PORT__::
    Advertise the directory service on this port.

**DirListenAddress** __IP__[:__PORT__]::
    Bind the directory service to this address. If you specify a port, bind to
    this port rather than the one specified in DirPort.  (Default: 0.0.0.0)
    This directive can be specified multiple times  to bind to multiple
    addresses/ports.

**DirPolicy** __policy__,__policy__,__...__::
    Set an entrance policy for this server, to limit who can connect to the
    directory ports. The policies have the same form as exit policies above.

DIRECTORY AUTHORITY SERVER OPTIONS
----------------------------------

**RecommendedVersions** __STRING__::
    STRING is a comma-separated list of Tor versions currently believed to be
    safe. The list is included in each directory, and nodes which pull down the
    directory learn whether they need to upgrade. This option can appear
    multiple times: the values from multiple lines are spliced together. When
    this is set then **VersioningAuthoritativeDirectory** should be set too.

**RecommendedClientVersions** __STRING__::
    STRING is a comma-separated list of Tor versions currently believed to be
    safe for clients to use. This information is included in version 2
    directories. If this is not set then the value of **RecommendedVersions**
    is used. When this is set then **VersioningAuthoritativeDirectory** should
    be set too.

**RecommendedServerVersions** __STRING__::
    STRING is a comma-separated list of Tor versions currently believed to be
    safe for servers to use. This information is included in version 2
    directories. If this is not set then the value of **RecommendedVersions**
    is used. When this is set then **VersioningAuthoritativeDirectory** should
    be set too.

**ConsensusParams** __STRING__::
    STRING is a space-separated list of key=value pairs that Tor will include
    in the "params" line of its networkstatus vote.

**DirAllowPrivateAddresses** **0**|**1**::
    If set to 1, Tor will accept router descriptors with arbitrary "Address"
    elements. Otherwise, if the address is not an IP address or is a private IP
    address, it will reject the router descriptor. Defaults to 0.

**AuthDirBadDir** __AddressPattern...__::
    Authoritative directories only. A set of address patterns for servers that
    will be listed as bad directories in any network status document this
    authority publishes, if **AuthDirListBadDirs** is set.

**AuthDirBadExit** __AddressPattern...__::
    Authoritative directories only. A set of address patterns for servers that
    will be listed as bad exits in any network status document this authority
    publishes, if **AuthDirListBadExits** is set.

**AuthDirInvalid** __AddressPattern...__::
    Authoritative directories only. A set of address patterns for servers that
    will never be listed as "valid" in any network status document that this
    authority publishes.

**AuthDirReject** __AddressPattern__...::
    Authoritative directories only. A set of address patterns for servers that
    will never be listed at all in any network status document that this
    authority publishes, or accepted as an OR address in any descriptor
    submitted for publication by this authority.

**AuthDirListBadDirs** **0**|**1**::
    Authoritative directories only. If set to 1, this directory has some
    opinion about which nodes are unsuitable as directory caches. (Do not set
    this to 1 unless you plan to list non-functioning directories as bad;
    otherwise, you are effectively voting in favor  of every declared
    directory.)

**AuthDirListBadExits** **0**|**1**::
    Authoritative directories only. If set to 1, this directory has some
    opinion about which nodes are unsuitable as exit nodes. (Do not set this to
    1 unless you plan to list non-functioning exits as bad; otherwise, you are
    effectively voting in favor of every declared exit as an exit.)

**AuthDirRejectUnlisted** **0**|**1**::
    Authoritative directories only. If set to 1, the directory server rejects
    all uploaded server descriptors that aren't explicitly listed in the
    fingerprints file. This acts as a "panic button" if we get hit with a Sybil
    attack. (Default: 0)

**AuthDirMaxServersPerAddr** __NUM__::
    Authoritative directories only. The maximum number of servers that we will
    list as acceptable on a single IP address. Set this to "0" for "no limit".
    (Default: 2)

**AuthDirMaxServersPerAuthAddr** __NUM__::
    Authoritative directories only. Like AuthDirMaxServersPerAddr, but applies
    to addresses shared with directory authorities. (Default: 5)

**V3AuthVotingInterval** __N__ **minutes**|**hours**::
    V3 authoritative directories only. Configures the server's preferred voting
    interval. Note that voting will __actually__ happen at an interval chosen
    by consensus from all the authorities' preferred intervals. This time
    SHOULD divide evenly into a day. (Default: 1 hour)

**V3AuthVoteDelay** __N__ **minutes**|**hours**::
    V3 authoritative directories only. Configures the server's preferred delay
    between publishing its vote and assuming it has all the votes from all the
    other authorities. Note that the actual time used is not the server's
    preferred time, but the consensus of all preferences. (Default: 5 minutes.)

**V3AuthDistDelay** __N__ **minutes**|**hours**::
    V3 authoritative directories only. Configures the server's preferred  delay
    between publishing its consensus and signature and assuming  it has all the
    signatures from all the other authorities. Note that the actual time used
    is not the server's preferred time,  but the consensus of all preferences.
    (Default: 5 minutes.)

**V3AuthNIntervalsValid** __NUM__::
    V3 authoritative directories only. Configures the number of VotingIntervals
    for which each consensus should be valid for. Choosing high numbers
    increases network partitioning risks; choosing low numbers increases
    directory traffic. Note that the actual number of intervals used is not the
    server's preferred number, but the consensus of all preferences. Must be at
    least 2. (Default: 3.)

HIDDEN SERVICE OPTIONS
----------------------

The following options are used to configure a hidden service.

**HiddenServiceDir** __DIRECTORY__::
    Store data files for a hidden service in DIRECTORY. Every hidden service
    must have a separate directory. You may use this option  multiple times to
    specify multiple services.

**HiddenServicePort** __VIRTPORT__ [__TARGET__]::
    Configure a virtual port VIRTPORT for a hidden service. You may use this
    option multiple times; each time applies to the service using the most
    recent hiddenservicedir. By default, this option maps the virtual port to
    the same port on 127.0.0.1. You may override the target port, address, or
    both by specifying a target of addr, port, or addr:port. You may also have
    multiple lines with  the same VIRTPORT: when a user connects to that
    VIRTPORT, one of the TARGETs from those lines will be chosen at random.

**PublishHidServDescriptors** **0**|**1**::
    If set to 0, Tor will run any hidden services you configure, but it won't
    advertise them to the rendezvous directory. This option is only useful if
    you're using a Tor controller that handles hidserv publishing for you.
    (Default: 1)

**HiddenServiceVersion** __version__,__version__,__...__::
    A list of rendezvous service descriptor versions to publish for the hidden
    service. Currently, only version 2 is supported. (Default: 2)

**HiddenServiceAuthorizeClient** __auth-type__ __client-name__,__client-name__,__...__::
    If configured, the hidden service is accessible for authorized clients
    only. The auth-type can either be \'basic' for a general-purpose
    authorization protocol or \'stealth' for a less scalable protocol that also
    hides service activity from unauthorized clients. Only clients that are
    listed here are authorized to access the hidden service. Valid client names
    are 1 to 19 characters  long and only use characters in A-Za-z0-9+-_ (no
    spaces). If this option is set, the hidden service is not accessible for
    clients without authorization any more. Generated authorization data can be
    found in the hostname file. Clients need to put this authorization data in
    their configuration file using **HidServAuth**.

**RendPostPeriod** __N__ **seconds**|**minutes**|**hours**|**days**|**weeks**::
    Every time the specified period elapses, Tor uploads any rendezvous 
    service descriptors to the directory servers. This information  is also
    uploaded whenever it changes. (Default: 20 minutes)

TESTING NETWORK OPTIONS
-----------------------

The following options are used for running a testing Tor network.

**TestingTorNetwork** **0**|**1**::
    If set to 1, Tor adjusts default values of the configuration options below,
    so that it is easier to set up a testing Tor network. May only be set if
    non-default set of DirServers is set. Cannot be unset while Tor is running.
    (Default: 0) +

       ServerDNSAllowBrokenConfig 1
       DirAllowPrivateAddresses 1
       EnforceDistinctSubnets 0
       AssumeReachable 1
       AuthDirMaxServersPerAddr 0
       AuthDirMaxServersPerAuthAddr 0
       ClientDNSRejectInternalAddresses 0
       ExitPolicyRejectPrivate 0
       V3AuthVotingInterval 5 minutes
       V3AuthVoteDelay 20 seconds
       V3AuthDistDelay 20 seconds
       TestingV3AuthInitialVotingInterval 5 minutes
       TestingV3AuthInitialVoteDelay 20 seconds
       TestingV3AuthInitialDistDelay 20 seconds
       TestingAuthDirTimeToLearnReachability 0 minutes
       TestingEstimatedDescriptorPropagationTime 0 minutes

**TestingV3AuthInitialVotingInterval** __N__ **minutes**|**hours**::
    Like V3AuthVotingInterval, but for initial voting interval before the first
    consensus has been created. Changing this requires that
    **TestingTorNetwork** is set. (Default: 30 minutes)

**TestingV3AuthInitialVoteDelay** __N__ **minutes**|**hours**::
    Like TestingV3AuthInitialVoteDelay, but for initial voting interval before
    the first consensus has been created. Changing this requires that
    **TestingTorNetwork** is set. (Default: 5 minutes)

**TestingV3AuthInitialDistDelay** __N__ **minutes**|**hours**::
    Like TestingV3AuthInitialDistDelay, but for initial voting interval before
    the first consensus has been created. Changing this requires that
    **TestingTorNetwork** is set. (Default: 5 minutes)

**TestingAuthDirTimeToLearnReachability** __N__ **minutes**|**hours**::
    After starting as an authority, do not make claims about whether routers
    are Running until this much time has passed. Changing this requires
    that **TestingTorNetwork** is set.  (Default: 30 minutes)

**TestingEstimatedDescriptorPropagationTime** __N__ **minutes**|**hours**::
    Clients try downloading router descriptors from directory caches after this
    time. Changing this requires that **TestingTorNetwork** is set. (Default:
    10 minutes)

SIGNALS
-------

Tor catches the following signals:

**SIGTERM**::
    Tor will catch this, clean up and sync to disk if necessary, and exit.

**SIGINT**::
    Tor clients behave as with SIGTERM; but Tor servers will do a controlled
    slow shutdown, closing listeners and waiting 30 seconds before exiting.
    (The delay can be configured with the ShutdownWaitLength config option.)

**SIGHUP**:: 
    The signal instructs Tor to reload its configuration (including closing and
    reopening logs), fetch a new directory, and kill and restart its helper
    processes if applicable.

**SIGUSR1**::
    Log statistics about current connections, past connections, and throughput.

**SIGUSR2**::
    Switch all logs to loglevel debug. You can go back to the old loglevels by
    sending a SIGHUP.

**SIGCHLD**::
    Tor receives this signal when one of its helper processes has exited, so it
    can clean up.

**SIGPIPE**::
    Tor catches this signal and ignores it.

**SIGXFSZ**::
    If this signal exists on your platform, Tor catches and ignores it.

FILES
-----

**@CONFDIR@/torrc**::
    The configuration file, which contains "option value" pairs.

**@LOCALSTATEDIR@/lib/tor/**::
    The tor process stores keys and other data here.

__DataDirectory__**/cached-status/**::
    The most recently downloaded network status document for each authority.
    Each file holds one such document; the filenames are the hexadecimal
    identity key fingerprints of the directory authorities.

__DataDirectory__**/cached-descriptors** and **cached-descriptors.new**::
    These files hold downloaded router statuses. Some routers may appear more
    than once; if so, the most recently published descriptor is used. Lines
    beginning with @-signs are annotations that contain more information about
    a given router. The ".new" file is an append-only journal; when it gets
    too large, all entries are merged into a new cached-descriptors file.

__DataDirectory__**/cached-routers** and **cached-routers.new**::
    Obsolete versions of cached-descriptors and cached-descriptors.new. When
    Tor can't find the newer files, it looks here instead.

__DataDirectory__**/state**::
    A set of persistent key-value mappings. These are documented in
    the file. These include:
            - The current entry guards and their status.
            - The current bandwidth accounting values (unused so far; see
            below).
            - When the file was last written
            - What version of Tor generated the state file
            - A short history of bandwidth usage, as produced in the router
            descriptors.

__DataDirectory__**/bw_accounting**::
    Used to track bandwidth accounting values (when the current period starts
    and ends; how much has been read and written so far this period). This file
    is obsolete, and the data is now stored in the \'state' file as well. Only
    used when bandwidth accounting is enabled.

__DataDirectory__**/control_auth_cookie**::
    Used for cookie authentication with the controller. Location can be
    overridden by the CookieAuthFile config option. Regenerated on startup. See
    control-spec.txt for details. Only used when cookie authentication is
    enabled.

__DataDirectory__**/keys/***::
    Only used by servers. Holds identity keys and onion keys.

__DataDirectory__**/fingerprint**::
    Only used by servers. Holds the fingerprint of the server's identity key.

__DataDirectory__**/approved-routers**::
    Only for naming authoritative directory servers (see
    **NamingAuthoritativeDirectory**). This file lists nickname to identity
    bindings. Each line lists a nickname and a fingerprint separated by
    whitespace. See your **fingerprint** file in the __DataDirectory__ for an
    example line. If the nickname is **!reject** then descriptors from the
    given identity (fingerprint) are rejected by this server. If it is
    **!invalid** then descriptors are accepted but marked in the directory as
    not valid, that is, not recommended.

__DataDirectory__**/router-stability**::
    Only used by authoritative directory servers. Tracks measurements for
    router mean-time-between-failures so that authorities have a good idea of
    how to set their Stable flags.

__HiddenServiceDirectory__**/hostname**::
    The <base32-encoded-fingerprint>.onion domain name for this hidden service.
    If the hidden service is restricted to authorized clients only, this file
    also contains authorization data for all clients.

__HiddenServiceDirectory__**/private_key**::
    The private key for this hidden service.

__HiddenServiceDirectory__**/client_keys**::
    Authorization data for a hidden service that is only accessible by
    authorized clients.

SEE ALSO
--------
**privoxy**(1), **tsocks**(1), **torify**(1) +

**https://www.torproject.org/**


BUGS
----

Plenty, probably. Tor is still in development. Please report them.

AUTHORS
-------
Roger Dingledine <mailto:arma@mit.edu[arma@mit.edu]>, Nick Mathewson <mailto:nickm@alum.mit.edu[nickm@alum.mit.edu]>.