tor.1.txt

// Copyright (c) The Tor Project, Inc.
// See LICENSE for licensing information
// This is an asciidoc file used to generate the manpage/html reference.
// Learn asciidoc on http://www.methods.co.nz/asciidoc/userguide.html
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" pairs. (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.   Options on the command line take precedence over
    options found in the configuration file, except indicated otherwise.  To
    split one configuration entry into multiple lines, use a single \ before
    the end of the line.  Comments can be used in such multiline entries, but
    they must start at the beginning of a line.

**BandwidthRate** __N__ **bytes**|**KB**|**MB**|**GB**::
    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.  If you want to run a relay in the
    public network, this needs to be _at the very least_ 20 KB (that is,
    20480 bytes). (Default: 5 MB)

**BandwidthBurst** __N__ **bytes**|**KB**|**MB**|**GB**::
    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**::
    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**::
    If not 0, 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**::
    If not 0, 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**::
    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**::
    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)

**ConnLimit** __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__|**auto**::
    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 or
    more of **HashedControlPassword** or **CookieAuthentication**,
    setting this option will cause Tor to allow any process on the local
    host to control it. (Setting both authentication methods means either
    method is sufficient to authenticate to Tor.) This
    option is required for many Tor controllers; most use the value of 9051.
    Set it to "auto" to have Tor pick a port for you. (Default: 0).

**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.)

**ControlSocketsGroupWritable** **0**|**1**::
    If this option is set to 0, don't allow the filesystem group to read and
    write unix sockets (e.g. ControlSocket). If the option is set to 1, make
    the control socket readable and writable by the default GID. (Default: 0)

**HashedControlPassword** __hashed_password__::
    Allow connections on the control port if they present
    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, allow connections on the control port
    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).

**ControlPortWriteToFile** __Path__::
    If set, Tor writes the address and port of any control port it opens to
    this address.  Usable by controllers to learn the actual control port
    when ControlPort is set to "auto".

**ControlPortFileGroupReadable** **0**|**1**::
    If this option is set to 0, don't allow the filesystem group to read the
    control port file. If the option is set to 1, make the control port
    file readable by the default GID. (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.

**Log** **[**__domain__,...**]**__minSeverity__[-__maxSeverity__] ... **file** __FILENAME__ +

**Log** **[**__domain__,...**]**__minSeverity__[-__maxSeverity__] ... **stderr**|**stdout**|**syslog**::
    As above, but select messages by range of log severity __and__ by a
    set of "logging domains".  Each logging domain corresponds to an area of
    functionality inside Tor.  You can specify any number of severity ranges
    for a single log statement, each of them prefixed by a comma-separated
    list of logging domains.  You can prefix a domain with $$~$$ to indicate
    negation, and use * to indicate "all domains".  If you specify a severity
    range without a list of domains, it matches all domains. +
 +
    This is an advanced feature which is most useful for debugging one or two
    of Tor's subsystems at a time. +
 +
    The currently recognized domains are: general, crypto, net, config, fs,
    protocol, mm, http, app, control, circ, rend, bug, dir, dirserv, or, edge,
    acct, hist, and handshake.  Domain names are case-insensitive. +
 +
    For example, "`Log [handshake]debug [~net,~mm]info notice stdout`" sends
    to stdout: all handshake messages of any severity, all info-and-higher
    messages from domains other than networking and memory management, and all
    messages of severity notice or higher.

**LogMessageDomains** **0**|**1**::
    If 1, Tor includes message domains with each log message.  Every log
    message currently has at least one domain; most currently have exactly
    one.  This doesn't affect controller log messages. (Default: 0)

**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.  This setting will be
    ignored for connections to the loopback addresses (127.0.0.0/8 and ::1).

**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.  Also note that relatively few clients turn off this option,
    so using these relays might make your client stand out.
    (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.

**LearnCircuitBuildTimeout** **0**|**1**::
    If 0, CircuitBuildTimeout adaptive learning is disabled. (Default: 1)

**CircuitBuildTimeout** __NUM__::

    Try for at most NUM seconds when building circuits. If the circuit isn't
    open in that time, give up on it. If LearnCircuitBuildTimeout is 1, this
    value serves as the initial value to use before a timeout is learned. If
    LearnCircuitBuildTimeout is 0, this value is the only value used.
    (Default: 60 seconds.)

**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 relay or serve
    directory requests. This config option is mostly meaningless: we
    added it back when we were considering having Tor clients auto-promote
    themselves to being relays if they were stable and fast enough. The
    current behavior is simply that Tor is a client unless ORPort or
    DirPort are configured. (Default: 0)

**ExcludeNodes** __node__,__node__,__...__::
    A list of identity fingerprints, nicknames, country codes and address
    patterns of nodes to avoid when building a circuit.
    (Example:
    ExcludeNodes SlowServer, ABCD1234CDEF5678ABCD1234CDEF5678ABCD1234, \{cc}, 255.254.0.0/8) +
 +
    By default, this option is treated as a preference that Tor is allowed
    to override in order to keep working.
    For example, if you try to connect to a hidden service,
    but you have excluded all of the hidden service's introduction points,
    Tor will connect to one of them anyway.  If you do not want this
    behavior, set the StrictNodes option (documented below).  +
 +
    Note also that if you are a relay, this (and the other node selection
    options below) only affects your own circuits that Tor builds for you.
    Clients can still build circuits through you to any node.  Controllers
    can tell Tor to build circuits through any node.


**ExcludeExitNodes** __node__,__node__,__...__::
    A list of identity fingerprints, nicknames, country codes and address
    patterns of nodes to never use when picking an exit node---that is, a
    node that delivers traffic for you outside the Tor network.   Note that any
    node listed in ExcludeNodes is automatically considered to be part of this
    list too.  See also the caveats on the "ExitNodes" option below.


**ExitNodes** __node__,__node__,__...__::
    A list of identity fingerprints, nicknames, country codes and address
    patterns of nodes to use as exit node---that is, a
    node that delivers traffic for you outside the Tor network. +
 +
    Note that if you list too few nodes here, or if you exclude too many exit
    nodes with ExcludeExitNodes, you can degrade functionality.  For example,
    if none of the exits you list allows traffic on port 80 or 443, you won't
    be able to browse the web. +
 +
    Note also that not every circuit is used to deliver traffic outside of
    the Tor network.  It is normal to see non-exit circuits (such as those
    used to connect to hidden services, those that do directory fetches,
    those used for relay reachability self-tests, and so on) that end
    at a non-exit node.  To
    keep a node from being used entirely, see ExcludeNodes and StrictNodes. +
 +
    The ExcludeNodes option overrides this option: any node listed in both
    ExitNodes and ExcludeNodes is treated as excluded. +
 +
    The .exit address notation, if enabled via AllowDotExit, overrides
    this option.

**EntryNodes** __node__,__node__,__...__::
    A list of identity fingerprints and nicknames of nodes
    to use for the first hop in your normal circuits.  (Country codes and
    address patterns are not yet supported.)  Normal circuits include all
    circuits except for direct connections to directory servers.  The Bridge
    option overrides this option; if you have configured bridges and
    UseBridges is 1, the Bridges are used as your entry nodes. +
 +
    The ExcludeNodes option overrides this option: any node listed in both
    EntryNodes and ExcludeNodes is treated as excluded.

**StrictNodes** **0**|**1**::
    If StrictNodes is set to 1, Tor will treat the ExcludeNodes option as a
    requirement to follow for all the circuits you generate, even if doing so
    will break functionality for you.  If StrictNodes is set to 0, Tor will
    still try to avoid nodes in the ExcludeNodes list, but it will err on the
    side of avoiding unexpected errors.  Specifically, StrictNodes 0 tells
    Tor that it is okay to use an excluded node when it is *necessary* to
    perform relay reachability self-tests, connect to
    a hidden service, provide a hidden service to a client, fulfill a .exit
    request, upload directory information, or download directory information.
    (Default: 0)

**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__|**auto**::
    Advertise this port to listen for connections from Socks-speaking
    applications. Set this to 0 if you don't want to allow application
    connections via SOCKS. Set it to "auto" to have Tor pick a port for
    you. (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)

**WarnUnsafeSocks** **0**|**1**::
    When this option is enabled, Tor will warn whenever a request is
    received that only contains an IP address instead of a hostname. Allowing
    applications to do DNS resolves themselves is usually a bad idea and
    can leak your location to attackers. (Default: 1)

**VirtualAddrNetwork** __Address__/__bits__::
    When Tor needs to assign a virtual (unused) address because of a MAPADDRESS
    command from the controller or the AutomapHostsOnResolve feature, 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__|**auto**::
    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.  Set it to "auto" to have Tor pick a
    port for you.  (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__|**auto**::
    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.  Set it to "auto" to have Tor
    pick a port for you. (Default: 0)

**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__|**auto**::
    If non-zero, Tor listens for UDP DNS requests on this port and resolves
    them anonymously.  Set it to "auto" to have Tor pick a port for
    you. (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).

**ClientRejectInternalAddresses** **0**|**1**::
    If true, Tor does not try to fulfill requests to connect to an internal
    address (like 127.0.0.1 or 192.168.0.1) __unless a exit node is
    specifically requested__ (for example, via a .exit hostname, or a
    controller request).  (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).

**AllowSingleHopCircuits** **0**|**1**::
    When this option is set, the attached Tor controller can use relays
    that have the **AllowSingleHopExits** option turned on to build
    one-hop Tor connections.  (Default: 0)

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.  This IP address is the one used to tell clients and other
    servers where to find your Tor server; it doesn't affect the IP that your
    Tor client binds to.  To bind to a different address, use the
    *ListenAddress and OutboundBindAddress options.

**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.  Note that most clients will refuse to use
    servers that set this option, since most clients have
    ExcludeSingleHopRelays set.  (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. It mainly causes Tor to publish a
    server descriptor to the bridge database, rather than publishing a relay
    descriptor to the public directory authorities.

**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__|**auto**::
    Advertise this port to listen for connections from Tor clients and
    servers.  This option is required to be a Tor server.
    Set it to "auto" to have Tor pick a port for you. (Default: 0).

**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**,**...**::
    This option specifies which descriptors Tor will publish when acting as
    a relay. You can
    choose multiple arguments, separated by commas.
 +
    If this option is set to 0, Tor will not publish its
    descriptors to any directories. (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 descriptors of all
    type(s) specified. The default is "1",
    which means "if running as a server, publish the
    appropriate descriptors to the 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)