TOR(1)

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.

COMMAND-LINE OPTIONS

-h, -help: Display a short help message and exit.
-f FILE: Specify a new configuration file to contain further Tor configuration options. (Default: /etc/tor/torrc, or $HOME/.torrc if that file is not found)
--defaults-torrc FILE: Specify a file in which to find default values for Tor options. The contents of this file are overridden by those in the regular configuration file, and by those on the command line. (Default: /etc/tor/torrc-defaults.)
--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.
--service install [--options command-line options]: Install an instance of Tor as a Windows service, with the provided command-line options. Current instructions can be found at https://trac.torproject.org/projects/tor/wiki/doc/TorFAQ#HowdoIrunmyTorrelayasanNTservice
--service remove|start|stop: Remove, start, or stop a configured Tor Windows service.
--nt-service: Used internally to implement a Windows service.
--list-torrc-options: List all valid options.
--version: Display Tor version and exit.
--quiet|--hush: Override the default console log. By default, Tor starts out logging messages at level "notice" and higher to the console. It stops doing so after it parses its configuration, if the configuration tells it to log anywhere else. You can override this behavior with the --hush option, which tells Tor to only send warnings and errors to the console, or with the --quiet option, which tells Tor not to log to the console at all.

Other options can be specified on the command-line in the format "--option value", in the format "option value", or in a configuration file. For instance, you can tell Tor to start listening for SOCKS connections on port 9999 by passing --SOCKSPort 9999 or SOCKSPort 9999 to it on the command line, or by putting "SOCKSPort 9999" in the configuration file. You will need to quote options with spaces in them: if you want Tor to log all debugging messages to debug.log, you will probably need to say --Log debug file debug.log.

Options on the command line override those in configuration files. See the next section for more information.

THE CONFIGURATION FILE FORMAT

All configuration options in a configuration are written on a single line by default. They take the form of an option name and a value, or an option name and a quoted value (option value or option "value"). Anything after a # character is treated as a comment. Options are case-insensitive. C-style escaped characters are allowed inside quoted values. To split one configuration entry into multiple lines, use a single backslash character (\) before the end of the line. Comments can be used in such multiline entries, but they must start at the beginning of a line.

By default, an option on the command line overrides an option found in the configuration file, and an option in a configuration file overrides one in the defaults file.

This rule is simple for options that take a single value, but it can become complicated for options that are allowed to occur more than once: if you specify four SOCKSPorts in your configuration file, and one more SOCKSPort on the command line, the option on the command line will replace all of the SOCKSPorts in the configuration file. If this isn’t what you want, prefix the option name with a plus sign, and it will be appended to the previous set of options instead.

Alternatively, you might want to remove every instance of an option in the configuration file, and not replace it at all: you might want to say on the command line that you want no SOCKSPorts at all. To do that, prefix the option name with a forward slash.

GENERAL OPTIONS

BandwidthRate N bytes|KBytes|MBytes|GBytes: 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 30 KBytes (that is, 30720 bytes). (Default: 1 GByte)
BandwidthBurst N bytes|KBytes|MBytes|GBytes: Limit the maximum token bucket size (also known as the burst) to the given number of bytes in each direction. (Default: 1 GByte)
MaxAdvertisedBandwidth N bytes|KBytes|MBytes|GBytes: 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|KBytes|MBytes|GBytes: 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|KBytes|MBytes|GBytes: 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|KBytes|MBytes|GBytes: 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|KBytes|MBytes|GBytes: 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)
ClientTransportPlugin transport socks4|socks5 IP:PORT
ClientTransportPlugin transport exec path-to-binary [options]: In its first form, when set along with a corresponding Bridge line, the Tor client forwards its traffic to a SOCKS-speaking proxy on "IP:PORT". It’s the duty of that proxy to properly forward the traffic to the bridge.

In its second form, when set along with a corresponding Bridge line, the Tor client launches the pluggable transport proxy executable in path-to-binary using options as its command-line options, and forwards its traffic to it. It’s the duty of that proxy to properly forward the traffic to the bridge.
ServerTransportPlugin transport exec path-to-binary [options]: The Tor relay launches the pluggable transport proxy in path-to-binary using options as its command-line options, and expects to receive proxied client traffic from it.
ServerTransportListenAddr transport IP:PORT: When this option is set, Tor will suggest IP:PORT as the listening address of any pluggable transport proxy that tries to launch transport.
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)
DisableNetwork 0|1: When this option is set, we don’t listen for or accept any connections other than controller connections, and we don’t make any outbound connections. Controllers sometimes use this option to avoid using the network until Tor is fully configured. (Default: 0)
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|KBytes: 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. This directive can be specified multiple times to bind to multiple addresses/ports. (Default: 127.0.0.1)
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: /var/lib/tor)
FallbackDir address:port orport=port id=fingerprint [weight=num]: When we’re unable to connect to any directory cache for directory info (usually because we don’t know about any yet) we try a FallbackDir. By default, the directory authorities are also FallbackDirs.
DirAuthority [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. If a flag "weight=num" is given, then the directory server is chosen randomly with probability proportional to that weight (default 1.0). 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 DirAuthority line is given, Tor will use the default directory authorities. 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.
DirAuthorityFallbackRate NUM: When configured to use both directory authorities and fallback directories, the directory authorities also work as fallbacks. They are chosen with their regular weights, multiplied by this number, which should be 1.0 or less. (Default: 1.0)
DynamicDHGroups 0|1: If this option is set to 1, when running as a server, generate our own Diffie-Hellman group instead of using the one from Apache’s mod_ssl. This option may help circumvent censorship based on static Diffie-Hellman parameters. (Default: 0)

AlternateDirAuthority [nickname] [flags] address:port fingerprint

AlternateHSAuthority [nickname] [flags] address:port fingerprint

AlternateBridgeAuthority [nickname] [flags] address:port fingerprint: These options behave as DirAuthority, but they replace fewer of the default directory authorities. Using AlternateDirAuthority replaces the default Tor directory authorities, but leaves the default hidden service authorities and bridge authorities in place. Similarly, AlternateHSAuthority replaces the default hidden service authorities, but not the directory or bridge authorities; and AlternateBridgeAuthority replaces the default bridge authority, but leaves the directory and hidden service authorities alone.
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)
DisableDebuggerAttachment 0|1: If set to 1, Tor will attempt to prevent basic debugging attachment attempts by other processes. This may also keep Tor from generating core files if it crashes. It has no impact for users who wish to attach if they have CAP_SYS_PTRACE or if they are root. We believe that this feature works on modern Gnu/Linux distributions, and that it may also work on *BSD systems (untested). Some modern Gnu/Linux systems such as Ubuntu have the kernel.yama.ptrace_scope sysctl and by default enable it as an attempt to limit the PTRACE scope for all user processes by default. This feature will attempt to limit the PTRACE scope for Tor specifically - it will not attempt to alter the system wide ptrace scope as it may not even exist. If you wish to attach to Tor with a debugger such as gdb or strace you will want to set this to 0 for the duration of your debugging. Normal users should leave it on. Disabling this option while Tor is running is prohibited. (Default: 1)
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 option may be used twice, once with an IPv4 address and once with an IPv6 address. 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)
LogTimeGranularity NUM: Set the resolution of timestamps in Tor’s logs to NUM milliseconds. NUM must be positive and either a divisor or a multiple of 1 second. Note that this option only controls the granularity written by Tor to a file or console log. Tor does not (for example) "batch up" log messages to affect times logged by a controller, times attached to syslog messages, or the mtime fields on log files. (Default: 1 second)
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)
DisableIOCP 0|1: If Tor was built to use the Libevent’s "bufferevents" networking code and you’re running on Windows, setting this option to 1 will tell Libevent not to use the Windows IOCP networking API. (Default: 1)
UserspaceIOCPBuffers 0|1: If IOCP is enabled (see DisableIOCP above), setting this option to 1 will tell Tor to disable kernel-space TCP buffers, in order to avoid needless copy operations and try not to run out of non-paged RAM. This feature is experimental; don’t use it yet unless you’re eager to help tracking down bugs. (Default: 0)
_UseFilteringSSLBufferevents 0|1: Tells Tor to do its SSL communication using a chain of bufferevents: one for SSL and one for networking. This option has no effect if bufferevents are disabled (in which case it can’t turn on), or if IOCP bufferevents are enabled (in which case it can’t turn off). This option is useful for debugging only; most users shouldn’t touch it. (Default: 0)
CountPrivateBandwidth 0|1: If this option is set, then Tor’s rate-limiting applies not only to remote connections, but also to connections to private addresses like 127.0.0.1 or 10.0.0.1. This is mostly useful for debugging rate-limiting. (Default: 0)

CLIENT OPTIONS

The following options are useful only for clients (that is, if SocksPort, TransPort, DNSPort, or NATDPort is non-zero):

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 [transport] 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 DirAuthority), 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.

If "transport" is provided, and matches to a ClientTransportPlugin line, we use that pluggable transports proxy to transfer data to the bridge.

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.

Country codes are case-insensitive. The code "{??}" refers to nodes whose country can’t be identified. No country code, including {??}, works if no GeoIPFile can be loaded. See also the GeoIPExcludeUnknown option below.

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.

GeoIPExcludeUnknown 0|1|auto

If this option is set to auto, then whenever any country code is set in ExcludeNodes or ExcludeExitNodes, all nodes with unknown country ({??} and possibly {A1}) are treated as excluded as well. If this option is set to 1, then all unknown countries are treated as excluded in ExcludeNodes and ExcludeExitNodes. This option has no effect when a GeoIP file isn’t configured or can’t be found. (Default: auto)

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, nicknames, and country codes of nodes to use for the first hop in your normal circuits. 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)

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.

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.

CloseHSClientCircuitsImmediatelyOnTimeout 0|1

If 1, Tor will close unfinished hidden service client circuits which have not moved closer to connecting to their destination hidden service when their internal state has not changed for the duration of the current circuit-build timeout. Otherwise, such circuits will be left open, in the hope that they will finish connecting to their destination hidden services. In either case, another set of introduction and rendezvous circuits for the same destination hidden service will be launched. (Default: 0)

CloseHSServiceRendCircuitsImmediatelyOnTimeout 0|1

If 1, Tor will close unfinished hidden-service-side rendezvous circuits after the current circuit-build timeout. Otherwise, such circuits will be left open, in the hope that they will finish connecting to their destinations. In either case, another rendezvous circuit for the same destination client will be launched. (Default: 0)

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. Note that the list is also honored for circuits (both client and service side) involving hidden services whose virtual port is in this list. (Default: 21, 22, 706, 1863, 5050, 5190, 5222, 5223, 6523, 6667, 6697, 8300)

MapAddress address newaddress

When a request for address arrives to Tor, it will transform to newaddress before processing it. For example, if you always want connections to www.example.com to exit via torserver (where torserver is the nickname of the server), use "MapAddress www.example.com www.example.com.torserver.exit". If the value is prefixed with a "*.", matches an entire domain. For example, if you always want connections to example.com and any if its subdomains to exit via torserver (where torserver is the nickname of the server), use "MapAddress *.example.com *.example.com.torserver.exit". (Note the leading "*." in each part of the directive.) You can also redirect all subdomains of a domain to a single address. For example, "MapAddress *.example.com www.example.com".

NOTES:

When evaluating MapAddress expressions Tor stops when it hits the most recently added expression that matches the requested address. So if you have the following in your torrc, www.torproject.org will map to 1.1.1.1:
```
MapAddress www.torproject.org 2.2.2.2
MapAddress www.torproject.org 1.1.1.1
```
Tor evaluates the MapAddress configuration until it finds no matches. So if you have the following in your torrc, www.torproject.org will map to 2.2.2.2:
```
MapAddress 1.1.1.1 2.2.2.2
MapAddress www.torproject.org 1.1.1.1
```
The following MapAddress expression is invalid (and will be ignored) because you cannot map from a specific address to a wildcard address:
```
MapAddress www.torproject.org *.torproject.org.torserver.exit
```
Using a wildcard to match only part of a string (as in *ample.com) is also invalid.

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. For hidden services, this applies to the last time a circuit was used, not the first. (Default: 10 minutes)

MaxClientCircuitsPending NUM

Do not allow more than NUM circuits to be pending at a time for handling client streams. A circuit is pending if we have begun constructing it, but it has not yet been completely constructed. (Default: 32)

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. In addition to nodes, you can also list IP address and ranges and country codes in {curly braces}.

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 [address:]port|auto [flags] [isolation flags]

Open 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. This directive can be specified multiple times to bind to multiple addresses/ports. (Default: 9050)

The isolation flags arguments give Tor rules for which streams received on this SOCKSPort are allowed to share circuits with one another. Recognized isolation flags are:

IsolateClientAddr

Don’t share circuits with streams from a different client address. (On by default and strongly recommended; you can disable it with NoIsolateClientAddr.)

IsolateSOCKSAuth

Don’t share circuits with streams for which different SOCKS authentication was provided. (On by default; you can disable it with NoIsolateSOCKSAuth.)

IsolateClientProtocol

Don’t share circuits with streams using a different protocol. (SOCKS 4, SOCKS 5, TransPort connections, NATDPort connections, and DNSPort requests are all considered to be different protocols.)

IsolateDestPort

Don’t share circuits with streams targetting a different destination port.

IsolateDestAddr

Don’t share circuits with streams targetting a different destination address.

SessionGroup=INT

If no other isolation rules would prevent it, allow streams on this port to share circuits with streams from every other port with the same session group. (By default, streams received on different SOCKSPorts, TransPorts, etc are always isolated from one another. This option overrides that behavior.)

Other recognized _flags_ for a SOCKSPort are:
**NoIPv4Traffic**;;
    Tell exits to not connect to IPv4 addresses in response to SOCKS
    requests on this connection.
**IPv6Traffic**;;
    Tell exits to allow IPv6 addresses in response to SOCKS requests on
    this connection, so long as SOCKS5 is in use.  (SOCKS4 can't handle
    IPv6.)
**PreferIPv6**;;
    Tells exits that, if a host has both an IPv4 and an IPv6 address,
    we would prefer to connect to it via IPv6. (IPv4 is the default.) +

   NOTE: Although this option allows you to specify an IP address
   other than localhost, you should do so only with extreme caution.
   The SOCKS protocol is unencrypted and (as we use it)
   unauthenticated, so exposing it in this way could leak your
   information to anybody watching your network, and allow anybody
   to use your computer as an open proxy.
**CacheIPv4DNS**;;
    Tells the client to remember IPv4 DNS answers we receive from exit
    nodes via this connection. (On by default.)
**CacheIPv6DNS**;;
    Tells the client to remember IPv6 DNS answers we receive from exit
    nodes via this connection.
**CacheDNS**;;
    Tells the client to remember all DNS answers we receive from exit
    nodes via this connection.
**UseIPv4Cache**;;
    Tells the client to use any cached IPv4 DNS answers we have when making
    requests via this connection. (NOTE: This option, along UseIPv6Cache
    and UseDNSCache, can harm your anonymity, and probably
    won't help performance as much as you might expect. Use with care!)
**UseIPv6Cache**;;
    Tells the client to use any cached IPv6 DNS answers we have when making
    requests via this connection.
**UseDNSCache**;;
    Tells the client to use any cached DNS answers we have when making
    requests via this connection.
**PreferIPv6Automap**;;
    When serving a hostname lookup request on this port that
    should get automapped (according to AutomapHostsOnResove),
    if we could return either an IPv4 or an IPv6 answer, prefer
    an IPv6 answer. (On by default.)
**PreferSOCKSNoAuth**;;
    Ordinarily, when an application offers both "username/password
    authentication" and "no authentication" to Tor via SOCKS5, Tor
    selects username/password authentication so that IsolateSOCKSAuth can
    work.  This can confuse some applications, if they offer a
    username/password combination then get confused when asked for
    one. You can disable this behavior, so that Tor will select "No
    authentication" when IsolateSOCKSAuth is disabled, or when this
    option is set.

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. (DEPRECATED: As of 0.2.3.x-alpha, you can now use multiple SOCKSPort entries, and provide addresses for SOCKSPort entries, so SOCKSListenAddress no longer has a purpose. For backward compatibility, SOCKSListenAddress is only allowed when SOCKSPort is just a port number.)

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