tor/doc/tor.1.in

.TH TOR 1 "January 2009" "TOR"
.SH NAME
tor \- The second-generation onion router
.SH SYNOPSIS
.B tor
[\fIOPTION value\fR]...
.SH DESCRIPTION
.I 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.
.PP
Basically \fItor\fR 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.
.SH OPTIONS
\fB-h, -help\fP
Display a short help message and exit.
.LP
.TP
\fB-f \fR\fIFILE\fP
FILE contains further "option value" pairs. (Default: @CONFDIR@/torrc)
.LP
.TP
\fB--hash-password\fP
Generates a hashed password for control port access.
.LP
.TP
\fB--list-fingerprint\fP
Generate your keys and output your nickname and fingerprint.
.LP
.TP
\fB--verify-config\fP
Verify the configuration file is valid.
.LP
.TP
\fB--nt-service\fP
\fB--service [install|remove|start|stop]\fP
Manage the Tor Windows NT/2000/XP service.  Current instructions can
be found at http://wiki.noreply.org/noreply/TheOnionRouter/TorFAQ#WinNTService
.LP
.TP
\fB--list-torrc-options\fP
List all valid options.
.LP
.TP
\fB--version\fP
Display Tor version and exit.
.LP
.TP
\fB--quiet\fP
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.)
.LP
.TP
Other options can be specified either on the command-line (\fI--option
value\fR), or in the configuration file (\fIoption value\fR or
\fIoption "value"\fR).  Options are case-insensitive.  C-style escaped
characters are allowed inside quoted values.
.LP
.TP
\fBBandwidthRate \fR\fIN\fR \fBbytes\fR|\fBKB\fR|\fBMB\fR|\fBGB\fR|\fBTB\fP
A token bucket limits the average incoming bandwidth usage on this node
to the specified number of bytes per second, and the average outgoing
bandwidth usage to that same value. (Default: 5 MB)
.LP
.TP
\fBBandwidthBurst \fR\fIN\fR \fBbytes\fR|\fBKB\fR|\fBMB\fR|\fBGB\fR|\fBTB\fP
Limit the maximum token bucket size (also known as the burst) to the
given number of bytes in each direction. (Default: 10 MB)
.LP
.TP
\fBMaxAdvertisedBandwidth \fR\fIN\fR \fBbytes\fR|\fBKB\fR|\fBMB\fR|\fBGB\fR|\fBTB\fP
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.
.LP
.TP
\fBRelayBandwidthRate \fR\fIN\fR \fBbytes\fR|\fBKB\fR|\fBMB\fR|\fBGB\fR|\fBTB\fP
If defined, a separate token bucket limits the average incoming bandwidth
usage for _relayed traffic_ on this node to the specified number of
bytes per second, and the average outgoing bandwidth usage to that same
value. Relayed traffic currently is calculated to include answers to directory
requests, but that may change in future versions. (Default: 0)
.LP
.TP
\fBRelayBandwidthBurst \fR\fIN\fR \fBbytes\fR|\fBKB\fR|\fBMB\fR|\fBGB\fR|\fBTB\fP
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)
.LP
.TP
\fBConnLimit \fR\fINUM\fP
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)
.LP
.TP
\fBConstrainedSockets \fR\fB0\fR|\fB1\fR\fP
If set, Tor will tell the kernel to attempt to shrink the buffers for all
sockets to the size specified in \fBConstrainedSockSize\fP.  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 \fBnot\fP 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.)
.LP
.TP
\fBConstrainedSockSize \fR\fIN\fR \fBbytes\fR|\fBKB\fP
When \fBConstrainedSockets\fP 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.
.LP
.TP
\fBControlPort \fR\fIPort\fP
If set, Tor will accept connections on this port and allow those
connections to control the Tor process using the Tor Control Protocol
(described in control-spec.txt).  Note: unless you also specify one of
\fBHashedControlPassword\fP or \fBCookieAuthentication\fP, setting
this option will cause Tor to allow any process on the local host to
control it. This option is required for many Tor controllers; most use
the value of 9051.
.LP
.TP
\fBControlListenAddress \fR\fIIP\fR[:\fIPORT\fR]\fP
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.
.LP
.TP
\fBControlSocket \fR\fIPath\fP
Like ControlPort, but listens on a Unix domain socket, rather than a TCP
socket.  (Unix and Unix-like systems only.)
.LP
.TP
\fBHashedControlPassword \fR\fIhashed_password\fP
Don't allow any connections on the control port except when the other process
knows the password whose one-way hash is \fIhashed_password\fP.  You can
compute the hash of a password by running "tor --hash-password
\fIpassword\fP". You can provide several acceptable passwords by using
more than HashedControlPassword line.
.LP
.TP
\fBCookieAuthentication \fR\fB0\fR|\fB1\fP
If this option is set to 1, don't allow any connections on the control port
except when the connecting process knows the contents of a file named
"control_auth_cookie", which Tor will create in its data directory.  This
authentication method should only be used on systems with good filesystem
security. (Default: 0)
.LP
.TP
\fBCookieAuthFile \fR\fIPath\fP
If set, this option overrides the default location and file name for Tor's
cookie file.  (See CookieAuthentication above.)
.LP
.TP
\fBCookieAuthFileGroupReadable \fR\fB0\fR|\fB1\fR|\fIGroupName\fP
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).
.LP
.TP
\fBDataDirectory \fR\fIDIR\fP
Store working data in DIR (Default: @LOCALSTATEDIR@/lib/tor)
.LP
.TP
\fBDirServer \fR[\fInickname\fR] [\fBflags\fR] \fIaddress\fR\fB:\fIport fingerprint\fP
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 \fBnot\fP set.  Tor will use this authority as a bridge
authoritative directory if the "bridge" flag is set.  If a flag
"orport=\fBport\fR" is given, Tor will use the given port when opening
encrypted tunnels to the dirserver.  Lastly, if a flag "v3ident=\fBfp\fR" is
given, the dirserver is a v3 directory authority whose v3 long-term
signing key has the fingerprint \fBfp\fR.

If no \fBdirserver\fP 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.
.LP
.TP
\fBAlternateDirAuthority \fR[\fInickname\fR] [\fBflags\fR] \fIaddress\fR\fB:\fIport fingerprint\fP
.LP
.TP
\fBAlternateHSAuthority \fR[\fInickname\fR] [\fBflags\fR] \fIaddress\fR\fB:\fIport fingerprint\fP
.LP
.TP
\fBAlternateBridgeAuthority \fR[\fInickname\fR] [\fBflags\fR] \fIaddress\fR\fB:\fIport fingerprint\fP
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.
.LP
.TP
\fBFetchDirInfoEarly \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBFetchDirInfoExtraEarly \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBFetchHidServDescriptors \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBFetchServerDescriptors \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBFetchUselessDescriptors \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBHTTPProxy\fR \fIhost\fR[:\fIport\fR]\fP
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.
.LP
.TP
\fBHTTPProxyAuthenticator\fR \fIusername:password\fP
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.
.LP
.TP
\fBHTTPSProxy\fR \fIhost\fR[:\fIport\fR]\fP
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 \fBFascistFirewall\fR
to restrict the set of ports you might try to connect to, if your HTTPS
proxy only allows connecting to certain ports.
.LP
.TP
\fBHTTPSProxyAuthenticator\fR \fIusername:password\fP
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.
.LP
.TP
\fBSocks4Proxy\fR \fIhost\fR[:\fIport\fR]\fP
Tor will make all OR connections through the SOCKS 4 proxy at host:port
(or host:1080 if port is not specified).
.LP
.TP
\fBSocks5Proxy\fR \fIhost\fR[:\fIport\fR]\fP
Tor will make all OR connections through the SOCKS 5 proxy at host:port
(or host:1080 if port is not specified).
.LP
.TP
\fBSocks5ProxyUsername\fR \fIusername\fP
.LP
.TP
\fBSocks5ProxyPassword\fR \fIpassword\fP
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.
.LP
.TP
\fBKeepalivePeriod \fR\fINUM\fP
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)
.LP
.TP
\fBLog \fR\fIminSeverity\fR[-\fImaxSeverity\fR] \fBstderr\fR|\fBstdout\fR|\fBsyslog\fR\fP
Send all messages between \fIminSeverity\fR and \fImaxSeverity\fR 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.
.LP
.TP
\fBLog \fR\fIminSeverity\fR[-\fImaxSeverity\fR] \fBfile\fR \fIFILENAME\fP
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.
.LP
.TP
\fBOutboundBindAddress \fR\fIIP\fP
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.
.LP
.TP
\fBPidFile \fR\fIFILE\fP
On startup, write our PID to FILE. On clean shutdown, remove FILE.
.LP
.TP
\fBProtocolWarnings \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBRunAsDaemon \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBSafeLogging \fR\fB0\fR|\fB1\fP
If 1, Tor replaces potentially sensitive strings in the logs
(e.g. addresses) 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. (Default: 1)
.LP
.TP
\fBUser \fR\fIUID\fP
On startup, setuid to this user and setgid to their primary group.
.LP
.TP
\fBHardwareAccel \fR\fB0\fR|\fB1\fP
If non-zero, try to use built-in (static) crypto hardware acceleration when
available. (Default: 0)
.LP
.TP
\fBAccelName \fR\fINAME\fP
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.
.LP
.TP
\fBAccelDir \fR\fIDIR\fP
Specify this option if using dynamic hardware acceleration and the engine
implementation library resides somewhere other than the OpenSSL default.
.LP
.TP
\fBAvoidDiskWrites \fR\fB0\fR|\fB1\fP
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)
.LP
.TP
\fBTunnelDirConns \fR\fB0\fR|\fB1\fP
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)
.LP
.TP
\fBPreferTunneledDirConns \fR\fB0\fR|\fB1\fP
If non-zero, we will avoid directory servers that don't support tunneled
directory connections, when possible. (Default: 1)

.SH CLIENT OPTIONS
.PP
The following options are useful only for clients (that is, if \fBSocksPort\fP is non-zero):
.LP
.TP
\fBAllowInvalidNodes\fR \fBentry\fR|\fBexit\fR|\fBmiddle\fR|\fBintroduction\fR|\fBrendezvous\fR|...\fP
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.
.LP
.TP
\fBExcludeSingleHopRelays \fR\fB0\fR|\fB1\fR\fP
This option controls whether circuits built by Tor will include relays with
the AllowSingleHopExits flag set to true.  If ExcludeSingleHopRelays is set to
0, these relays will be included.  Note that these relays might be at higher
risk of being seized or observed, so they are not normally included.
(Default: 1)
.LP
.TP
\fBBridge \fR\fIIP:ORPort\fR [fingerprint]\fP
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.
.LP
.TP
\fBCircuitBuildTimeout \fR\fINUM\fP
Try for at most NUM seconds when building circuits. If the circuit
isn't open in that time, give up on it.
(Default: 1 minute.)
.LP
.TP
\fBCircuitIdleTimeout \fR\fINUM\fP
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.)
.LP
.TP
\fBClientOnly \fR\fB0\fR|\fB1\fR\fP
If set to 1, Tor will under no circumstances run as a server or serve
directory requests. The default
is to run as a client unless ORPort is configured.  (Usually,
you don't need to set this; Tor is pretty smart at figuring out whether
you are reliable and high-bandwidth enough to be a useful server.)
(Default: 0)
.LP
.TP
\fBExcludeNodes \fR\fInode\fR,\fInode\fR,\fI...\fP
A list of identity fingerprints, nicknames, country codes and address patterns
of nodes to never use when building a circuit.  (Example: ExcludeNodes
SlowServer, $ABCDEFFFFFFFFFFFFFFF, {cc}, 255.254.0.0/8)
.LP
.TP
\fBExcludeExitNodes \fR\fInode\fR,\fInode\fR,\fI...\fP
A list of identity fingerprints, nicknames, country codes and address patterns
of nodes to never use when picking an exit node.  Note that any node
listed in ExcludeNodes is automatically considered to be part of this
list.
.LP
.TP
\fBEntryNodes \fR\fInode\fR,\fInode\fR,\fI...\fP
A list of identity fingerprints, nicknames, country codes and address patterns
of nodes to use for the first hop in the circuit.
These are treated only as preferences unless StrictEntryNodes (see
below) is also set.
.LP
.TP
\fBExitNodes \fR\fInode\fR,\fInode\fR,\fI...\fP
A list of identity fingerprints, nicknames, country codes and address patterns
of nodes to use for the last hop in the circuit.
These are treated only as preferences unless StrictExitNodes (see
below) is also set.
.LP
.TP
\fBStrictEntryNodes \fR\fB0\fR|\fB1\fR\fP
If 1, Tor will never use any nodes besides those listed in "EntryNodes" for
the first hop of a circuit.
.LP
.TP
\fBStrictExitNodes \fR\fB0\fR|\fB1\fR\fP
If 1, Tor will never use any nodes besides those listed in "ExitNodes" for
the last hop of a circuit.
.LP
.TP
\fBFascistFirewall \fR\fB0\fR|\fB1\fR\fP
If 1, Tor will only create outgoing connections to ORs running on ports that
your firewall allows (defaults to 80 and 443; see \fBFirewallPorts\fR).  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.
.LP
.TP
\fBFirewallPorts \fR\fIPORTS\fP
A list of ports that your firewall allows you to connect to.  Only
used when \fBFascistFirewall\fR is set. This option is deprecated; use
ReachableAddresses instead. (Default: 80, 443)
.LP
.TP
\fBHidServAuth \fR\fIonion-address\fR \fIauth-cookie\fP [\fIservice-name\fR]
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
\fBHiddenServiceAuthorizeClient\fR option.
.LP
.TP
\fBReachableAddresses \fR\fIADDR\fP[\fB/\fP\fIMASK\fP][:\fIPORT\fP]...\fP
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 *:*'.)
.LP
.TP
\fBReachableDirAddresses \fR\fIADDR\fP[\fB/\fP\fIMASK\fP][:\fIPORT\fP]...\fP
Like \fBReachableAddresses\fP, 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 \fBReachableAddresses\fP
is used.  If \fBHTTPProxy\fR is set then these connections will go through that
proxy.
.LP
.TP
\fBReachableORAddresses \fR\fIADDR\fP[\fB/\fP\fIMASK\fP][:\fIPORT\fP]...\fP
Like \fBReachableAddresses\fP, 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 \fBReachableAddresses\fP is used. If
\fBHTTPSProxy\fR is set then these connections will go through that proxy.

The separation between \fBReachableORAddresses\fP and
\fBReachableDirAddresses\fP is only interesting when you are connecting through
proxies (see \fBHTTPProxy\fR and \fBHTTPSProxy\fR).  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.
.LP
.TP
\fBLongLivedPorts \fR\fIPORTS\fP
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)
.LP
.TP
\fBMapAddress\fR \fIaddress\fR \fInewaddress\fR
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 \fItorserver\fR (where
\fItorserver\fR is the nickname of the server),
use "MapAddress www.indymedia.org www.indymedia.org.torserver.exit".
.LP
.TP
\fBNewCircuitPeriod \fR\fINUM\fP
Every NUM seconds consider whether to build a new circuit. (Default: 30 seconds)
.LP
.TP
\fBMaxCircuitDirtiness \fR\fINUM\fP
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)
.LP
.TP
\fBNodeFamily \fR\fInode\fR,\fInode\fR,\fI...\fP
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.
.LP
.TP
\fBEnforceDistinctSubnets \fR\fB0\fR|\fB1\fR\fP
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)

.\" \fBPathlenCoinWeight \fR\fI0.0-1.0\fP
.\" Paths are 3 hops plus a geometric distribution centered around this coinweight.
.\" Must be >=0.0 and <1.0. (Default: 0.3) NOT USED CURRENTLY
.\" .TP
.LP
.TP
\fBSocksPort \fR\fIPORT\fP
Advertise this port to listen for connections from Socks-speaking
applications.  Set this to 0 if you don't want to allow application
connections. (Default: 9050)
.LP
.TP
\fBSocksListenAddress \fR\fIIP\fR[:\fIPORT\fR]\fP
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.
.LP
.TP
\fBSocksPolicy \fR\fIpolicy\fR,\fIpolicy\fR,\fI...\fP
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.
.LP
.TP
\fBSocksTimeout \fR\fINUM\fP
Let a socks connection wait NUM seconds handshaking, and NUM seconds
unattached waiting for an appropriate circuit, before we fail it.
(Default: 2 minutes.)
.LP
.TP
\fBTrackHostExits \fR\fIhost\fR,\fI.domain\fR,\fI...\fR\fP
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.
.LP
.TP
\fBTrackHostExitsExpire \fR\fINUM\fP
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).
.LP
.TP
\fBUpdateBridgesFromAuthority \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBUseBridges \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBUseEntryGuards \fR\fB0\fR|\fB1\fR\fP
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.)
.LP
.TP
\fBNumEntryGuards \fR\fINUM\fP
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.)
.LP
.TP
\fBSafeSocks \fR\fB0\fR|\fB1\fR\fP
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.)
.LP
.TP
\fBTestSocks \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBVirtualAddrNetwork \fR\fIAddress\fB/\fIbits\fP
When a controller asks for a virtual (unused) address with the
MAPADDRESS command, Tor picks an unassigned address from this range.
(Default: 127.192.0.0/10)

When providing proxy server service to a network of computers using a tool like
dns-proxy-tor,
change this address to "10.192.0.0/10" or "172.16.0.0/12".
The default \fBVirtualAddrNetwork\fP address range on a 
properly configured machine will route to the loopback interface. 
For local use, no change to the
default \fBVirtualAddrNetwork\fP setting is needed.
.LP
.TP
\fBAllowNonRFC953Hostnames \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBAllowDotExit \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBFastFirstHopPK \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBTransPort\fP \fR\fIPORT\fP
If non-zero, enables transparent proxy support on \fR\fIPORT\fP (by
convention, 9040).
.\" This is required to enable support for \fBdns-proxy-tor\fP.
.\" ControlPort must be set when using \fBTransPort\fP.
Requires OS support for transparent proxies, such as BSDs' pf or
Linux's IPTables.
If you're planning 
to use Tor as a transparent proxy for a network, you'll want to examine 
and change VirtualAddrNetwork from the default setting. You'll also want
to set the TransListenAddress option for the network you'd like to proxy.
(Default: 0).
.LP
.TP
\fBTransListenAddress\fP \fR\fIIP\fR[:\fIPORT\fR]\fP
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.
.LP
.TP
\fBNATDPort\fP \fR\fIPORT\fP
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.
.LP
.TP
\fBNATDListenAddress\fP \fR\fIIP\fR[:\fIPORT\fR]\fP
Bind to this address to listen for NATD connections.
(Default: 127.0.0.1).
.LP
.TP
\fBAutomapHostsOnResolve\fP \fR\fB0\fR|\fB1\fR\fP
When this option is enabled, and we get a request to resolve an
address that ends with one of the suffixes in
\fBAutomapHostsSuffixes\fP, 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).
.LP
.TP
\fBAutomapHostsSuffixes\fP \fR\fISUFFIX\fR,\fISUFFIX\fR,...\fP
A comma-separated list of suffixes to use with \fBAutomapHostsOnResolve\fP.
The "." suffix is equivalent to "all addresses."
(Default: .exit,.onion).
.LP
.TP
\fBDNSPort\fP \fR\fIPORT\fP
If non-zero, Tor listens for UDP DNS requests on this port and resolves them
anonymously.
(Default: 0).
.LP
.TP
\fBDNSListenAddress\fP \fR\fIIP\fR[:\fIPORT\fR]\fP
Bind to this address to listen for DNS connections.
(Default: 127.0.0.1).
.LP
.TP
\fBClientDNSRejectInternalAddresses\fP \fR\fB0\fR|\fB1\fR\fP
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).
.LP
.TP
\fBDownloadExtraInfo\fP \fR\fB0\fR|\fB1\fR\fP
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).
.LP
.TP
\fBFallbackNetworkstatusFile\fP \fIFILENAME\fP
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).
.LP
.TP
\fBWarnPlaintextPorts\fP \fR\fIport\fR,\fIport\fR,\fI...\fP
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).
.LP
.TP
\fBRejectPlaintextPorts\fP \fR\fIport\fR,\fIport\fR,\fI...\fP
Like WarnPlaintextPorts, but instead of warning about risky port uses,
Tor will instead refuse to make the connection.
(Default: None).

.SH SERVER OPTIONS
.PP
The following options are useful only for servers (that is, if \fBORPort\fP is non-zero):
.LP
.TP
\fBAddress \fR\fIaddress\fP
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.
.LP
.TP
\fBAllowSingleHopExits \fR\fB0\fR|\fB1\fR\fP
This option controls whether clients can use this server as a single hop 
proxy.  If set to 1, clients can use this server as an exit even if it is
the only hop in the circuit.  (Default: 0)
.LP
.TP
\fBAssumeReachable \fR\fB0\fR|\fB1\fR\fP
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 \fBAuthoritativeDirectory\fP is also set, this option
instructs the dirserver to bypass remote reachability testing too and
list all connected servers as running.
.LP
.TP
\fBBridgeRelay \fR\fB0\fR|\fB1\fR\fP
Sets the relay to act as a "bridge" with respect to relaying connections
from bridge users to the Tor network. Mainly it influences how the relay
will cache and serve directory information. Usually used in combination
with PublishServerDescriptor.
.LP
.TP
\fBContactInfo \fR\fIemail_address\fP
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.
.LP
.TP
\fBExitPolicy \fR\fIpolicy\fR,\fIpolicy\fR,\fI...\fP
Set an exit policy for this server. Each policy is of the form
"\fBaccept\fP|\fBreject\fP \fIADDR\fP[\fB/\fP\fIMASK\fP]\fB[:\fP\fIPORT\fP]".
If \fB/\fP\fIMASK\fP is omitted then this policy just applies to the host
given.  Instead of giving a host or network you can also use "\fB*\fP" to
denote the universe (0.0.0.0/0).  \fIPORT\fP can be a single port number,
an interval of ports "\fIFROM_PORT\fP\fB-\fP\fITO_PORT\fP", or "\fB*\fP".
If \fIPORT\fP is omitted, that means "\fB*\fP".

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:
.PD 0
.RS 12
.IP "reject *:25"
.IP "reject *:119"
.IP "reject *:135-139"
.IP "reject *:445"
.IP "reject *:563"
.IP "reject *:1214"
.IP "reject *:4661-4666"
.IP "reject *:6346-6429"
.IP "reject *:6699"
.IP "reject *:6881-6999"
.IP "accept *:*"
.RE
.PD
.LP
.TP
\fBExitPolicyRejectPrivate \fR\fB0\fR|\fB1\fR\fP
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)
.LP
.TP
\fBMaxOnionsPending \fR\fINUM\fP
If you have more than this number of onionskins queued for decrypt, reject new ones. (Default: 100)
.LP
.TP
\fBMyFamily \fR\fInode\fR,\fInode\fR,\fI...\fP
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.)
.LP
.TP
\fBNickname \fR\fIname\fP
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].
.LP
.TP
\fBNumCPUs \fR\fInum\fP
How many processes to use at once for decrypting onionskins. (Default: 1)
.LP
.TP
\fBORPort \fR\fIPORT\fP
Advertise this port to listen for connections from Tor clients and servers.
.LP
.TP
\fBORListenAddress \fR\fIIP\fR[:\fIPORT\fR]\fP
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.
.LP
.TP
\fBPublishServerDescriptor \fR\fB0\fR|\fB1\fR|\fBv1\fR|\fBv2\fR|\fBv3\fR|\fBbridge\fR|\fBhidserv\fR, ...\fP
This option is only considered if you have an ORPort defined. You can
choose multiple arguments, separated by commas.

If set to 0, Tor will act as a server but it will not publish its
descriptor to the directory authorities. (This is useful if you're
testing out your server, or if you're using a Tor controller that handles
directory publishing for you.) Otherwise, Tor will publish its descriptor
to all directory authorities of the type(s) specified. The value "1" is
the default, which means "publish to the appropriate authorities".
.LP
.TP
\fBShutdownWaitLength\fR \fINUM\fP
When we get a SIGINT and we're a server, we begin shutting down: we close
listeners and start refusing new circuits. After \fBNUM\fP seconds,
we exit. If we get a second SIGINT, we exit immediately.  (Default:
30 seconds)
.LP
.TP
\fBAccountingMax \fR\fIN\fR \fBbytes\fR|\fBKB\fR|\fBMB\fR|\fBGB\fR|\fBTB\fP
Never send more than the specified number of bytes in a given
accounting period, or receive more than that number in the period.
For example, with AccountingMax set to 1 GB, a server could send 900 MB
and receive 800 MB and continue running. It will only hibernate once one
of the two reaches 1 GB.
When the number of bytes is exhausted, Tor will hibernate until some
time in the next accounting period.  To prevent all servers from
waking at the same time, Tor will also wait until a random point in
each period before waking up.  If you have bandwidth cost issues,
enabling hibernation is preferable to setting a low bandwidth, since it
provides users with a collection of fast servers that are up some of
the time, which is more useful than a set of slow servers that are
always "available".
.LP
.TP
\fBAccountingStart \fR\fBday\fR|\fBweek\fR|\fBmonth\fR [\fIday\fR] \fIHH:MM\fR\fP
Specify how long accounting periods last.  If \fBmonth\fP is given,
each accounting period runs from the time \fIHH:MM\fR on the
\fIday\fRth day of one month to the same day and time of the next.
(The day must be between 1 and 28.)  If \fBweek\fP is given, each
accounting period runs from the time \fIHH:MM\fR of the \fIday\fRth
day of one week to the same day and time of the next week, with Monday
as day 1 and Sunday as day 7.  If \fBday\fR is given, each accounting
period runs from the time \fIHH:MM\fR each day to the same time on the
next day.  All times are local, and given in 24-hour time.  (Defaults to
"month 1 0:00".)
.LP
.TP
\fBServerDNSResolvConfFile \fR\fIfilename\fP
Overrides the default DNS configuration with the configuration in
\fIfilename\fP.  The file format is the same as the standard Unix
"\fBresolv.conf\fP" file (7).  This option, like all other
ServerDNS options, only affects name lookups that your server does on
behalf of clients. (Defaults to use the system DNS configuration.)
.LP
.TP
\fBServerDNSAllowBrokenConfig \fR\fB0\fR|\fB1\fR\fP
If this option is false, Tor exits immediately if there are problems
parsing the system DNS configuration or connecting to nameservers.
Otherwise, Tor continues to periodically retry the system nameservers
until it eventually succeeds.
(Defaults to "1".)
.LP
.TP
\fBServerDNSSearchDomains \fR\fB0\fR|\fB1\fR\fP
If set to \fB1\fP, then we will search for addresses in the local search
domain.  For example, if this system is configured to believe it is in
"example.com", and a client tries to connect to "www", the client will be
connected to "www.example.com".
This option only affects name lookups that your server does on
behalf of clients.
(Defaults to "0".)
.LP
.TP
\fBServerDNSDetectHijacking \fR\fB0\fR|\fB1\fR\fP
When this option is set to 1, we will test periodically to determine whether
our local nameservers have been configured to hijack failing DNS requests
(usually to an advertising site).  If they are, we will attempt to correct
this.
This option only affects name lookups that your server does on
behalf of clients.
(Defaults to "1".)
.LP
.TP
\fBServerDNSTestAddresses \fR\fIaddress\fR,\fIaddress\fR,\fI...\fP
When we're detecting DNS hijacking, make sure that these \fIvalid\fP
addresses aren't getting redirected.  If they are, then our DNS is
completely useless, and we'll reset our exit policy to "reject *:*".
This option only affects name lookups that your server does on
behalf of clients.
(Defaults to "www.google.com, www.mit.edu, www.yahoo.com,
www.slashdot.org".)
.LP
.TP
\fBServerDNSAllowNonRFC953Hostnames \fR\fB0\fR|\fB1\fR\fP
When this option is disabled, Tor does not try to resolve hostnames
containing illegal characters (like @ and :) rather than sending them to an
exit node to be resolved.  This helps trap accidental attempts to resolve
URLs and so on.
This option only affects name lookups that your server does on
behalf of clients.
(Default: 0)
.LP
.TP
\fBBridgeRecordUsageByCountry \fR\fB0\fR|\fB1\fR\fP
When this option is enabled and BridgeRelay is also enabled, and we
have GeoIP data, Tor keeps a keep a per-country count of how many
client addresses have contacted it so that it can help the bridge
authority guess which countries have blocked access to it. (Default: 1)
.LP
.TP
\fBServerDNSRandomizeCase \fR\fB0\fR|\fB1\fR\fP
When this option is set, Tor sets the case of each character randomly in
outgoing DNS requests, and makes sure that the case matches in DNS replies.
This so-called "0x20 hack" helps resist some types of DNS poisoning attack.
For more information, see "Increased DNS Forgery Resistance through 0x20-Bit
Encoding".
This option only affects name lookups that your server does on
behalf of clients.
(Default: 1)
.LP
.TP
\fBGeoIPFile \fR\fIfilename\fP
A filename containing GeoIP data, for use with BridgeRecordUsageByCountry.
.LP
.TP
\fBCellStatistics \fR\fB0\fR|\fB1\fR\fP
When this option is enabled, Tor writes statistics on the mean time that
cells spend in circuit queues to disk every 24 hours. Cannot be changed
while Tor is running. (Default: 0)
.LP
.TP
\fBDirReqStatistics \fR\fB0\fR|\fB1\fR\fP
When this option is enabled, Tor writes statistics on the number and
response time of network status requests to disk every 24 hours. Cannot be
changed while Tor is running. (Default: 0)
.LP
.TP
\fBEntryStatistics \fR\fB0\fR|\fB1\fR\fP
When this option is enabled, Tor writes statistics on the number of
directly connecting clients to disk every 24 hours. Cannot be changed
while Tor is running. (Default: 0)
.LP
.TP
\fBExitPortStatistics \fR\fB0\fR|\fB1\fR\fP
When this option is enabled, Tor writes statistics on the number of
relayed bytes and opened stream per exit port to disk every 24 hours.
Cannot be changed while Tor is running. (Default: 0)
.LP
.TP
\fBExtraInfoStatistics \fR\fB0\fR|\fB1\fR\fP
When this option is enabled, Tor includes previously gathered statistics
in its extra-info documents that it uploads to the directory authorities.
(Default: 0)

.SH DIRECTORY SERVER OPTIONS
.PP
The following options are useful only for directory servers (that is, if \fBDirPort\fP is non-zero):
.LP
.TP
\fBAuthoritativeDirectory \fR\fB0\fR|\fB1\fR\fP
When this option is set to 1, Tor operates as an authoritative
directory server.  Instead of caching the directory, it generates its
own list of good servers, signs it, and sends that to the clients.
Unless the clients already have you listed as a trusted directory, you
probably do not want to set this option.  Please coordinate with the other
admins at tor-ops@freehaven.net if you think you should be a directory.
.LP
.TP
\fBDirPortFrontPage \fIFILENAME\fP
When this option is set, it takes an HTML file and publishes it as "/" on
the DirPort. Now relay operators can provide a disclaimer without needing
to set up a separate webserver. There's a sample disclaimer in
contrib/tor-exit-notice.html.
.LP
.TP
\fBV1AuthoritativeDirectory \fR\fB0\fR|\fB1\fR\fP
When this option is set in addition to \fBAuthoritativeDirectory\fP, Tor
generates version 1 directory and running-routers documents (for legacy
Tor clients up to 0.1.0.x).
.LP
.TP
\fBV2AuthoritativeDirectory \fR\fB0\fR|\fB1\fR\fP
When this option is set in addition to \fBAuthoritativeDirectory\fP, Tor
generates version 2 network statuses and serves descriptors, etc as
described in doc/spec/dir-spec-v2.txt (for Tor clients and servers
running 0.1.1.x and 0.1.2.x).
.LP
.TP
\fBV3AuthoritativeDirectory \fR\fB0\fR|\fB1\fR\fP
When this option is set in addition to \fBAuthoritativeDirectory\fP, Tor
generates version 3 network statuses and serves descriptors, etc as
described in doc/spec/dir-spec.txt (for Tor clients and servers
running at least 0.2.0.x).
.LP
.TP
\fBVersioningAuthoritativeDirectory \fR\fB0\fR|\fB1\fR\fP
When this option is set to 1, Tor adds information on
which versions of Tor are still believed safe for use to
the published directory.  Each version 1 authority is
automatically a versioning authority; version 2 authorities
provide this service optionally.  See \fBRecommendedVersions\fP,
\fBRecommendedClientVersions\fP, and \fBRecommendedServerVersions\fP.
.LP
.TP
\fBNamingAuthoritativeDirectory \fR\fB0\fR|\fB1\fR\fP
When this option is set to 1, then the server advertises that it has
opinions about nickname-to-fingerprint bindings.  It will include these
opinions in its published network-status pages, by listing servers with
the flag "Named" if a correct binding between that nickname and
fingerprint has been registered with the dirserver.  Naming dirservers
will refuse to accept or publish descriptors that contradict a
registered binding.  See \fBapproved-routers\fP in the \fBFILES\fP
section below.
.LP
.TP
\fBHSAuthoritativeDir \fR\fB0\fR|\fB1\fR\fP
When this option is set in addition to \fBAuthoritativeDirectory\fP, Tor also
accepts and serves hidden service descriptors. (Default: 0)
.LP
.TP
\fBHSAuthorityRecordStats \fR\fB0\fR|\fB1\fR\fP
When this option is set in addition to \fBHSAuthoritativeDir\fP, Tor
periodically (every 15 minutes) writes statistics about hidden service
usage to a file \fBhsusage\fP  in its data directory. (Default: 0)
.LP
.TP
\fBHidServDirectoryV2 \fR\fB0\fR|\fB1\fR\fP
When this option is set, Tor accepts and serves v2 hidden service
descriptors. Setting DirPort is not required for this, because clients
connect via the ORPort by default. (Default: 1)
.LP
.TP
\fBBridgeAuthoritativeDir \fR\fB0\fR|\fB1\fR\fP
When this option is set in addition to \fBAuthoritativeDirectory\fP, Tor
accepts and serves router descriptors, but it caches and serves the main
networkstatus documents rather than generating its own. (Default: 0)
.LP
.TP
\fBMinUptimeHidServDirectoryV2 \fR\fIN\fR \fBseconds\fR|\fBminutes\fR|\fBhours\fR|\fBdays\fR|\fBweeks\fP
Minimum uptime of a v2 hidden service directory to be accepted as such by
authoritative directories. (Default: 24 hours)
.LP
.TP
\fBDirPort \fR\fIPORT\fP
Advertise the directory service on this port.
.LP
.TP
\fBDirListenAddress \fR\fIIP\fR[:\fIPORT\fR]\fP
Bind the directory service to this address. If you specify a port, bind
to this port rather than the one specified in DirPort. (Default: 0.0.0.0)
This directive can be specified multiple times to bind to multiple
addresses/ports.
.LP
.TP
\fBDirPolicy \fR\fIpolicy\fR,\fIpolicy\fR,\fI...\fP
Set an entrance policy for this server, to limit who can connect to the
directory ports.
The policies have the same form as exit policies above.

.SH DIRECTORY AUTHORITY SERVER OPTIONS
.PP
.LP
.TP
\fBRecommendedVersions \fR\fISTRING\fP
STRING is a comma-separated list of Tor versions currently believed
to be safe. The list is included in each directory, and nodes which
pull down the directory learn whether they need to upgrade.  This
option can appear multiple times: the values from multiple lines are
spliced together.
When this is set then
\fBVersioningAuthoritativeDirectory\fP should be set too.
.LP
.TP
\fBRecommendedClientVersions \fR\fISTRING\fP
STRING is a comma-separated list of Tor versions currently believed
to be safe for clients to use.  This information is included in version 2
directories.  If this is not set then the value of \fBRecommendedVersions\fR
is used.
When this is set then
\fBVersioningAuthoritativeDirectory\fP should be set too.
.LP
.TP
\fBRecommendedServerVersions \fR\fISTRING\fP
STRING is a comma-separated list of Tor versions currently believed
to be safe for servers to use.  This information is included in version 2
directories.  If this is not set then the value of \fBRecommendedVersions\fR
is used.
When this is set then
\fBVersioningAuthoritativeDirectory\fP should be set too.
.LP
.TP
\fBDirAllowPrivateAddresses \fR\fB0\fR|\fB1\fR\fP
If set to 1, Tor will accept router descriptors with arbitrary "Address"
elements. Otherwise, if the address is not an IP address or is a private
IP address, it will reject the router descriptor. Defaults to 0.
.LP
.TP
\fBAuthDirBadDir \fR\fIAddressPattern\fR...\fP
Authoritative directories only.  A set of address patterns for servers that
will be listed as bad directories in any network status document this authority
publishes, if \fBAuthDirListBadDirs\fR is set.
.LP
.TP
\fBAuthDirBadExit \fR\fIAddressPattern\fR...\fP
Authoritative directories only.  A set of address patterns for servers that
will be listed as bad exits in any network status document this authority
publishes, if \fBAuthDirListBadExits\fR is set.
.LP
.TP
\fBAuthDirInvalid \fR\fIAddressPattern\fR...\fP
Authoritative directories only. A set of address patterns for servers that
will never be listed as "valid" in any network status document that this
authority publishes.
.LP
.TP
\fBAuthDirReject \fR\fIAddressPattern\fR...\fP
Authoritative directories only.  A set of address patterns for servers that
will never be listed at all in any network status document that this
authority publishes, or accepted as an OR address in any descriptor submitted
for publication by this authority.
.LP
.TP
\fBAuthDirListBadDirs \fR\fB0\fR|\fB1\fR\fP
Authoritative directories only.  If set to 1, this directory has
some opinion about which nodes are unsuitable as directory caches.  (Do not
set this to 1 unless you plan to list non-functioning directories as bad;
otherwise, you are effectively voting in favor of every declared directory.)
.LP
.TP
\fBAuthDirListBadExits \fR\fB0\fR|\fB1\fR\fP
Authoritative directories only.  If set to 1, this directory has
some opinion about which nodes are unsuitable as exit nodes.  (Do not
set this to 1 unless you plan to list non-functioning exits as bad;
otherwise, you are effectively voting in favor of every declared exit
as an exit.)
.LP
.TP
\fBAuthDirRejectUnlisted \fR\fB0\fR|\fB1\fR\fP
Authoritative directories only.  If set to 1, the directory server
rejects all uploaded server descriptors that aren't explicitly listed
in the fingerprints file. This acts as a "panic button" if we get
hit with a Sybil attack. (Default: 0)
.LP
.TP
\fBAuthDirMaxServersPerAddr\fR \fINUM\fP
Authoritative directories only.  The maximum number of servers that we
will list as acceptable on a single IP address.  Set this to "0" for
"no limit". (Default: 2)
.LP
.TP
\fBAuthDirMaxServersPerAuthAddr\fR \fINUM\fP
Authoritative directories only.  Like AuthDirMaxServersPerAddr, but
applies to addresses shared with directory authorities.  (Default: 5)
.LP
.TP
\fBV3AuthVotingInterval\fR \fR\fIN\fR \fBminutes\fR|\fBhours\fP
V3 authoritative directories only.  Configures the server's preferred
voting interval.  Note that voting will \fIactually\fP happen at an
interval chosen by consensus from all the authorities' preferred
intervals.  This time SHOULD divide evenly into a day. (Default: 1 hour)
.LP
.TP
\fBV3AuthVoteDelay\fR \fR\fIN\fR \fBminutes\fR|\fBhours\fP
V3 authoritative directories only.  Configures the server's preferred
delay between publishing its vote and assuming it has all the votes
from all the other authorities.  Note that the actual time used is not
the server's preferred time, but the consensus of all preferences.
(Default: 5 minutes.)
.LP
.TP
\fBV3AuthDistDelay\fR \fR\fIN\fR \fBminutes\fR|\fBhours\fP
V3 authoritative directories only.  Configures the server's preferred
delay between publishing its consensus and signature and assuming it
has all the signatures from all the other authorities.  Note that the
actual time used is not the server's preferred time, but the consensus
of all preferences.  (Default: 5 minutes.)
.LP
.TP
\fBV3AuthNIntervalsValid\fR \fINUM\fP
V3 authoritative directories only.  Configures the number of
VotingIntervals for which each consensus should be valid for.
Choosing high numbers increases network partitioning risks; choosing
low numbers increases directory traffic. Note that the actual number
of intervals used is not the server's preferred number, but the
consensus of all preferences.  Must be at least 2.  (Default: 3.)


.SH HIDDEN SERVICE OPTIONS
.PP
The following options are used to configure a hidden service.
.LP
.TP
\fBHiddenServiceDir \fR\fIDIRECTORY\fP
Store data files for a hidden service in DIRECTORY.  Every hidden
service must have a separate directory.  You may use this option multiple
times to specify multiple services.
.LP
.TP
\fBHiddenServicePort \fR\fIVIRTPORT \fR[\fITARGET\fR]\fP
Configure a virtual port VIRTPORT for a hidden service.  You may use this
option multiple times; each time applies to the service using the most recent
hiddenservicedir.  By default, this option maps the virtual port to the
same port on 127.0.0.1.  You may override the target port, address, or both
by specifying a target of addr, port, or addr:port.  You may also have
multiple lines with the same VIRTPORT: when a user connects to that VIRTPORT,
one of the TARGETs from those lines will be chosen at random.
.LP
.TP
\fBPublishHidServDescriptors \fR\fB0\fR|\fB1\fR\fP
If set to 0, Tor will run any hidden services you configure, but it won't
advertise them to the rendezvous directory. This option is only useful
if you're using a Tor controller that handles hidserv publishing for you.
(Default: 1)
.LP
.TP
\fBHiddenServiceVersion \fR\fIversion\fR,\fIversion\fR,\fI...\fP
A list of rendezvous service descriptor versions to publish for the hidden
service. Possible version numbers are 0 and 2. (Default: 0, 2)
.LP
.TP
\fBHiddenServiceAuthorizeClient \fR\fIauth-type\fR \fR\fIclient-name\fR,\fIclient-name\fR,\fI...\fP
If configured, the hidden service is accessible for authorized clients
only. The auth-type can either be 'basic' for a general-purpose
authorization protocol or 'stealth' for a less scalable protocol that also
hides service activity from unauthorized clients. Only clients that are
listed here are authorized to access the hidden service. Valid client names
are 1 to 19 characters long and only use characters in A-Za-z0-9+-_
(no spaces). If this option is set, the hidden service is not accessible
for clients without authorization any more. Generated authorization data
can be found in the hostname file. Clients need to put this authorization
data in their configuration file using \fBHidServAuth\fR.
.LP
.TP
\fBRendPostPeriod \fR\fIN\fR \fBseconds\fR|\fBminutes\fR|\fBhours\fR|\fBdays\fR|\fBweeks\fP
Every time the specified period elapses, Tor uploads any rendezvous
service descriptors to the directory servers.  This information is also
uploaded whenever it changes.  (Default: 20 minutes)

.SH TESTING NETWORK OPTIONS
.PP
The following options are used for running a testing Tor network.
.LP
.TP
\fBTestingTorNetwork \fR\fB0\fR|\fB1\fR\fP
If set to 1, Tor adjusts default values of the configuration options below,
so that it is easier to set up a testing Tor network. May only be set if
non-default set of DirServers is set. Cannot be unset while Tor is running.
(Default: 0)

.PD 0
.RS 12
.IP "ServerDNSAllowBrokenConfig 1"
.IP "DirAllowPrivateAddresses 1"
.IP "EnforceDistinctSubnets 0"
.IP "AssumeReachable 1"
.IP "AuthDirMaxServersPerAddr 0"
.IP "AuthDirMaxServersPerAuthAddr 0"
.IP "ClientDNSRejectInternalAddresses 0"
.IP "ExitPolicyRejectPrivate 0"
.IP "V3AuthVotingInterval 5 minutes"
.IP "V3AuthVoteDelay 20 seconds"
.IP "V3AuthDistDelay 20 seconds"
.IP "TestingV3AuthInitialVotingInterval 5 minutes"
.IP "TestingV3AuthInitialVoteDelay 20 seconds"
.IP "TestingV3AuthInitialDistDelay 20 seconds"
.IP "TestingAuthDirTimeToLearnReachability 0 minutes"
.IP "TestingEstimatedDescriptorPropagationTime 0 minutes"
.RE
.PD
.LP
.TP
\fBTestingV3AuthInitialVotingInterval\fR \fR\fIN\fR \fBminutes\fR|\fBhours\fP
Like \fBV3AuthVotingInterval\fR, but for initial voting interval before the
first consensus has been created. Changing this requires that
\fBTestingTorNetwork\fR is set. (Default: 30 minutes)
.LP
.TP
\fBTestingV3AuthInitialVoteDelay\fR \fR\fIN\fR \fBminutes\fR|\fBhours\fP
Like \fBTestingV3AuthInitialVoteDelay\fR, but for initial voting interval
before the first consensus has been created. Changing this requires that
\fBTestingTorNetwork\fR is set. (Default: 5 minutes)
.LP
.TP
\fBTestingV3AuthInitialDistDelay\fR \fR\fIN\fR \fBminutes\fR|\fBhours\fP
Like \fBTestingV3AuthInitialDistDelay\fR, but for initial voting interval
before the first consensus has been created. Changing this requires that
\fBTestingTorNetwork\fR is set. (Default: 5 minutes)
.LP
.TP
\fBTestingAuthDirTimeToLearnReachability\fR \fR\fIN\fR \fBminutes\fR|\fBhours\fP
After starting as an authority, do not make claims about whether routers are
Running until this much time has passed.
Changing this requires that\fBTestingTorNetwork\fR is set.
(Default: 30 minutes)
.LP
.TP
\fBTestingEstimatedDescriptorPropagationTime\fR \fR\fIN\fR \fBminutes\fR|\fBhours\fP
Clients try downloading router descriptors from directory caches after this
time. Changing this requires that \fBTestingTorNetwork\fR is set.
(Default: 10 minutes)

.\" UNDOCUMENTED
.\" ignoreversion

.SH SIGNALS
Tor catches the following signals:
.LP
.TP
\fBSIGTERM\fR
Tor will catch this, clean up and sync to disk if necessary, and exit.
.LP
.TP
\fBSIGINT\fR
Tor clients behave as with SIGTERM; but Tor servers will do a controlled
slow shutdown, closing listeners and waiting 30 seconds before exiting.
(The delay can be configured with the ShutdownWaitLength config option.)
.LP
.TP
\fBSIGHUP\fR
The signal instructs Tor to reload its configuration (including closing
and reopening logs), fetch a new directory, and kill and restart its
helper processes if applicable.
.LP
.TP
\fBSIGUSR1\fR
Log statistics about current connections, past connections, and
throughput.
.LP
.TP
\fBSIGUSR2\fR
Switch all logs to loglevel debug. You can go back to the old loglevels
by sending a SIGHUP.
.LP
.TP
\fBSIGCHLD\fR
Tor receives this signal when one of its helper processes has exited,
so it can clean up.
.LP
.TP
\fBSIGPIPE\fR
Tor catches this signal and ignores it.
.LP
.TP
\fBSIGXFSZ\fR
If this signal exists on your platform, Tor catches and ignores it.

.SH FILES
.LP
.TP
.B @CONFDIR@/torrc
The configuration file, which contains "option value" pairs.
.LP
.TP
.B @LOCALSTATEDIR@/lib/tor/
The tor process stores keys and other data here.
.LP
.TP
.B \fIDataDirectory\fP/cached-status/*
The most recently downloaded network status document for each authority.  Each file holds one such document; the filenames are the hexadecimal identity key fingerprints of the directory authorities.
.LP
.TP
.B \fIDataDirectory\fB/cached-descriptors\fR and \fBcached-descriptors.new\fR
These files hold downloaded router statuses.  Some routers may appear more than once; if so, the most recently published descriptor is used.    Lines beginning with @-signs are annotations that contain more information about a given router.  The ".new" file is an append-only journal; when it gets too large, all entries are merged into a new cached-routers file.
.LP
.TP
.B \fIDataDirectory\fB/cached-routers\fR and \fBcached-routers.new\fR
Obsolete versions of cached-descriptors and cached-descriptors.new.  When Tor can't find the newer files, it looks here instead.
.LP
.TP
.B \fIDataDirectory\fP/state
A set of persistent key-value mappings.  These are documented in the file.  These include:
.PD 0
.RS 5
.IP "- The current entry guards and their status."
.IP "- The current bandwidth accounting values (unused so far; see below)."
.IP "- When the file was last written"
.IP "- What version of Tor generated the state file"
.IP "- A short history of bandwidth usage, as produced in the router descriptors."
.RE
.PD
.LP
.TP
.B \fIDataDirectory\fP/bw_accounting
Used to track bandwidth accounting values (when the current period starts and ends; how much has been read and written so far this period).  This file is obsolete, and the data is now stored in the 'state' file as well.  Only used when bandwidth accounting is enabled.
.LP
.TP
.B \fIDataDirectory\fP/hsusage
Used to track hidden service usage in terms of fetch and publish
requests to this hidden service authoritative directory. Only used when
recording of statistics is enabled.
.LP
.TP
.B \fIDataDirectory\fP/control_auth_cookie
Used for cookie authentication with the controller. Location can be
overridden by the CookieAuthFile config option. Regenerated on startup.
See control-spec.txt for details.  Only used when cookie authentication
is enabled.
.LP
.TP
.B \fIDataDirectory\fP/keys/*
Only used by servers.  Holds identity keys and onion keys.
.LP
.TP
.B \fIDataDirectory\fP/fingerprint
Only used by servers.  Holds the fingerprint of the server's identity key.
.LP
.TP
.B \fIDataDirectory\fP/approved-routers
Only for naming authoritative directory servers (see \fBNamingAuthoritativeDirectory\fP).  This file lists nickname to identity bindings.  Each line lists a nickname and a fingerprint separated by whitespace.  See your \fBfingerprint\fP file in the \fIDataDirectory\fP for an example line.  If the nickname is \fB!reject\fP then descriptors from the given identity (fingerprint) are rejected by this server. If it is \fB!invalid\fP then descriptors are accepted but marked in the directory as not valid, that is, not recommended.
.LP
.TP
.B \fIDataDirectory\fP/router-stability
Only used by authoritative directory servers.  Tracks measurements for router mean-time-between-failures so that authorities have a good idea of how to set their Stable flags.
.LP
.TP
.B \fIHiddenServiceDirectory\fP/hostname 
The <base32-encoded-fingerprint>.onion domain name for this hidden service.
If the hidden service is restricted to authorized clients only, this file
also contains authorization data for all clients.
.LP
.TP
.B \fIHiddenServiceDirectory\fP/private_key 
The private key for this hidden service.
.LP
.TP
.B \fIHiddenServiceDirectory\fP/client_keys 
Authorization data for a hidden service that is only accessible by authorized
clients.
.SH SEE ALSO
.BR privoxy (1),
.BR tsocks (1),
.BR torify (1)

.BR https://www.torproject.org/

.SH BUGS
Plenty, probably. Tor is still in development. Please report them.
.SH AUTHORS
Roger Dingledine <arma@mit.edu>, Nick Mathewson <nickm@alum.mit.edu>.