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TOR

Section: Maintenance Commands (8)
Updated: November 2004
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NAME

tor - The second-generation onion router

SYNOPSIS

tor [OPTION value]...

DESCRIPTION

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

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

OPTIONS

-h, -help Display a short help message and exit.

-f FILE: FILE contains further "option value" pairs. (Default: /etc/tor/torrc)
Other options can be specified either on the command-line (--option: value), or in the configuration file (option value). Options are case-insensitive.
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. 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.
BandwidthRate N bytes|KB|MB|GB|TB: A token bucket limits the average incoming bandwidth on this node to the specified number of bytes per second. (Default: 780 KB)
BandwidthBurst N bytes|KB|MB|GB|TB: Limit the maximum token bucket size (also known as the burst) to the given number of bytes. (Default: 48 MB)
DataDirectory DIR: Store working data in DIR (Default: /var/lib/tor)
DirServer 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. If no dirserver line is given, Tor will use the default directory servers: moria1, moria2, and tor26.
Group GID: On startup, setgid to this user.
HttpProxy host[:port]: If set, Tor will make all its directory requests through this host:port, rather than connecting directly to any directory servers.
KeepalivePeriod NUM: To keep firewalls from expiring connections, send a padding keepalive cell on open connections every NUM seconds. (Default: 5 minutes.)
MaxConn NUM: Maximum number of simultaneous sockets allowed. You probably don't need to adjust this. (Default: 1024)
OutboundBindAddress IP: Make all outbound connections originate from the IP address specified. This is only useful when you have multiple network interfaces, and you want all of Tor's outgoing connections to use a single one.
PIDFile FILE: On startup, write our PID to FILE. On clean shutdown, remove FILE.
RunAsDaemon 0|1: If 1, Tor forks and daemonizes to the background. (Default: 0)
User UID: On startup, setuid to this user.
ControlPort Port: If set, Tor will accept connections from the same machine (localhost only) on this port, and allow those connections to control the Tor process using the Tor Control Protocol (described in control-spec.txt). Note: unless you also specify one of HashedControlPassword or CookieAuthentication, setting this option will cause Tor to allow any process on the local host to control it.
HashedControlPassword hashed_password: Don't allow any connections on the control port except when the other process knows the password whose one-way hash is hashed_password. You can compute the hash of a password by running "tor --hash-password password".
CookieAuthentication 0|1: If this option is set to 1, don't allow any connections on the control port except when the connecting process knows the contents of a file named "control_auth_cookie", which Tor will create in its data directory. This authentication methods should only be used on systems with good filesystem security. DirFetchPeriod N seconds|minutes|hours|days|weeks Every time the specified period elapses, Tor downloads a directory. A directory contains a signed list of all known servers as well as their current liveness status. (Default: 1 hour)
StatusFetchPeriod N seconds|minutes|hours|days|weeks: Every time the specified period elapses, Tor downloads signed status information about the current state of known servers. (Default: 20 minutes.)
RendPostPeriod N seconds|minutes|hours|days|weeks: Every time the specified period elapses, Tor uploads any rendezvous service descriptors to the directory servers. This information is also uploaded whenever it changes. (Default: 20 minutes.)

CLIENT OPTIONS

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

AllowUnverifiedNodes entry|exit|middle|introduction|rendezvous|...: Where on our circuits should we allow Tor servers that the directory servers haven't authenticated as "verified"? (Default: middle,rendezvous.)
ClientOnly 0|1: If set to 1, Tor will under no circumstances run as a server. (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 good server.)
EntryNodes nickname,nickname,...: A list of preferred nodes to use for the first hop in the circuit, if possible.
ExitNodes nickname,nickname,...: A list of preferred nodes to use for the last hop in the circuit, if possible.
ExcludeNodes nickname,nickname,...: A list of nodes to never use when building a circuit.
StrictExitNodes 0|1: If 1, Tor will never use any nodes besides those listed in "exitnodes" for the last hop of a circuit.
StrictEntryNodes 0|1: If 1, Tor will never use any nodes besides those listed in "entrynodes" for the first hop of a circuit.
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.
FirewallPorts PORTS: A list of ports that your firewall allows you to connect to. Only used when FascistFirewall is set. (Default: 80, 443.)
: NewCircuitPeriod NUM Every NUM seconds consider whether to build a new circuit. (Default: 60)
NodeFamily nickname,nickname,...: The named Tor servers 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.
: RendNodes nickname,nickname,... A list of preferred nodes to use for the rendezvous point, if possible.
RendExcludeNodes nickname,nickname,...: A list of nodes to never use when choosing a rendezvous point.
SOCKSPort PORT: Bind to 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)
SOCKSBindAddress IP: Bind to this address to listen for connections from socks-speaking applications. (Default: 127.0.0.1) You can also specify a port (e.g. 192.168.0.1:9100). This directive can be specified multiple times to bind to multiple addresses/ports.
SOCKSPolicy policy,policy,...: Set an entrance policy for this server, to limit who can connect to the socks ports. The policies have the same form as exit policies below.

SERVER OPTIONS

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

Address address

The IP or fqdn of this server (e.g. moria.mit.edu). You can leave this unset, and Tor will guess your IP.

ContactInfo email_address

Administrative contact information for server.

ExitPolicy policy,policy,...

Set an exit policy for this server. Each policy is of the form "accept|reject ADDR[/MASK]:PORT". If /MASK is omitted then this policy just applies to the host given. Instead of giving a host or network you can also use "*" to denote the universe (0.0.0.0/0). PORT can be a single port number, an interval of ports "FROM_PORT-TO_PORT", or "*".

For example, "reject 127.0.0.1:*,reject 192.168.1.0/24:*,accept *:*" would reject any traffic destined for localhost and any 192.168.1.* address, but accept anything else.

This directive can be specified multiple times so you don't have to put it all on one line.

See RFC 3330 for more details about internal and reserved IP address space. Policies are considered first to last, and the first match wins. If you want to _replace_ the default exit policy, end your exit policy with either a reject *:* or an accept *:*. Otherwise, you're _augmenting_ (prepending to) the default exit policy. The default exit policy is:

reject 0.0.0.0/8
reject 169.254.0.0/16
reject 127.0.0.0/8
reject 192.168.0.0/16
reject 10.0.0.0/8
reject 172.16.0.0/12
accept *:20-22
accept *:53
accept *:79-81
accept *:110
accept *:143
accept *:443
accept *:706
accept *:873
accept *:993
accept *:995
reject *:4661-4662
reject *:1214
reject *:6346
accept *:1024-65535
reject *:*

MaxOnionsPending NUM

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

MyFamily nickname,nickname,...

Declare that this Tor server is controlled or administered by a group or organization identical or similar to that of the other named servers. 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 need to list the other servers in its family; it doesn't need to list itself.)

Nickname name

Set the server's nickname to 'name'.

NumCPUs num

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

ORPort PORT

Bind to this port to listen for connections from Tor clients and servers.

ORBindAddress IP

Bind to this address to listen for connections from Tor clients and servers. (Default: 0.0.0.0)

RedirectExit pattern target

Whenever an outgoing connection tries to connect to one of a given set of addresses, connect to target (an address:port pair) instead. The address pattern is given in the same format as for an exit policy. The address translation applies after exit policies are applied. Multiple RedirectExit options can be used: once any one has matched successfully, no subsequent rules are considered. You can specify that no redirection is to be performed on a given set of addresses by using the special target string "pass", which prevents subsequent rules from being considered.

DirPostPeriod N seconds|minutes|hours|days|weeks

Every time the specified period elapses, Tor uploads its server descriptors to the directory servers. This information is also uploaded whenever it changes. (Default: 20 minutes.)

AccountingMax N bytes|KB|MB|GB|TB

Never send more than the specified number of bytes in a given accounting period, or receive more than that number in the period. 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, using this option is preferable to setting a low bandwidth, since it provides users with a collection of fast servers that are up some of the time, which is more useful than a set of slow servers that are always "available".

AccountingStart day|week|month [day] HH:MM

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

DIRECTORY SERVER OPTIONS

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

AuthoritativeDirectory 0|1: When this option is set to 1, Tor operates as an authoritative directory server. Instead of caching the directory, it generates its own list of good servers, signs it, and sends that to the clients. Unless the clients already have you listed as a trusted directory, you probably do not want to set this option. Please coordinate with the other admins at tor-ops@freehaven.net if you think you should be a directory.
DirPort PORT: Bind the directory service to this port.
DirBindAddress IP: Bind the directory service to this address. (Default: 0.0.0.0)
DirPolicy policy,policy,...: Set an entrance policy for this server, to limit who can connect to the directory ports. The policies have the same form as exit policies above.
RecommendedVersions STRING: STRING is a command-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.
RunTesting 0|1: If set to 1, Tor tries to build circuits through all of the servers it knows about, so it can tell which are up and which are down. This option is only useful for authoritative directories, so you probably don't want to use it.

HIDDEN SERVICE OPTIONS

The following options are used to configure a hidden service.

HiddenServiceDir DIRECTORY

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

HiddenServicePort VIRTPORT [TARGET]

Configure a virtual port VIRTPORT for a hidden service. You may use this option multiple times; each time applies to the service using the most recent hiddenservicedir. By default, this option maps the virtual port to the same port on 127.0.0.1. You may override the target port, address, or both by specifying a target of addr, port, or addr:port.

HiddenServiceNodes nickname,nickname,...

If possible, use the specified nodes as introduction points for the hidden service.

HiddenServiceExcludeNodes nickname,nickname,...

Do not use the specified nodes as introduction points for the hidden service.

SIGNALS

Tor catches the following signals:

SIGTERM: Tor will catch this, clean up and sync to disk if necessary, and exit.
SIGINT: Tor clients behave as with SIGTERM; but Tor servers will do a controlled slow shutdown, closing listeners and waiting 30 seconds before exiting.
SIGHUP: The signal instructs Tor to reload its configuration, fetch a new directory, and kill and restart its helper processes if applicable.
SIGUSR1: Log statistics about current connections, past connections, and throughput.
SIGUSR2: Switch all logs to loglevel debug. You can go back to the old loglevels by sending a SIGHUP.
SIGCHLD: Tor receives this signal when one of its helper processes has exited, so it can clean up.
SIGPIPE: Tor catches this signal and ignores it.
SIGXFSZ: If this signal exists on your platform, Tor catches and ignores it.

FILES

/etc/tor/torrc: The configuration file, which contains "option value" pairs.
/etc/tor/dirservers: A list of directory servers, to bootstrap into the network.
/var/lib/tor/: The tor process stores keys and other data here.
/var/log/tor/: The tor server logs to this directory.
/var/run/tor/tor.pid: The PID of the tor (master) process is stored in this file.

BUGS

Plenty, probably. It's still in alpha. Please report them.

AUTHORS

Roger Dingledine <arma@mit.edu>, Nick Mathewson <nickm@alum.mit.edu>.

This document was created by man2html, using the manual pages.
Time: 21:47:46 GMT, February 15, 2005

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