Stem Docs



Directories that provide relay descriptor information. At a very high level tor works as follows...

  1. Volunteer starts a new tor relay, during which it sends a server descriptor to each of the directory authorities.
  2. Each hour the directory authorities make a vote that says who they think the active relays are in the network and some attributes about them.
  3. The directory authorities send each other their votes, and compile that into the consensus. This document is very similar to the votes, the only difference being that the majority of the authorities agree upon and sign this document. The idividual relay entries in the vote or consensus is called router status entries.
  4. Tor clients (people using the service) download the consensus from an authority, fallback, or other mirror to determine who the active relays in the network are. They then use this to construct circuits and use the network.
Directory - Relay we can retrieve descriptor information from
  | |- from_cache - Provides cached information bundled with Stem.
  | +- from_remote - Downloads the latest directory information from tor.
  |- Authority - Tor directory authority
  +- Fallback - Mirrors that can be used instead of the authorities

New in version 1.7.0.

class, or_port, dir_port, fingerprint, nickname, orport_v6)[source]

Bases: object

Relay we can contact for descriptor information.

Our from_cache() and from_remote() functions key off a different identifier based on our subclass...

This is because authorities are highly static and canonically known by their names, whereas fallbacks vary more and don't necessarily have a nickname to key off of.

  • address (str) -- IPv4 address of the directory
  • or_port (int) -- port on which the relay services relay traffic
  • dir_port (int) -- port on which directory information is available
  • fingerprint (str) -- relay fingerprint
  • nickname (str) -- relay nickname
  • orport_v6 (str) -- (address, port) tuple for the directory's IPv6 ORPort, or None if it doesn't have one
static from_cache()[source]

Provides cached Tor directory information. This information is hardcoded into Tor and occasionally changes, so the information provided by this method may not necessarily match the latest version of tor.

New in version 1.5.0.

Changed in version 1.7.0: Support added to the Authority class.

Returns:dict of str identifiers to Directory instances
static from_remote(timeout=60)[source]

Reads and parses tor's directory data from Note that while convenient, this reliance on GitWeb means you should alway call with a fallback, such as...

  authorities =
except IOError:
  authorities =

New in version 1.5.0.

Changed in version 1.7.0: Support added to the Authority class.

Parameters:timeout (int) -- seconds to wait before timing out the request
Returns:dict of str identifiers to their Directory
Raises :IOError if unable to retrieve the fallback directories
class, or_port=None, dir_port=None, fingerprint=None, nickname=None, orport_v6=None, v3ident=None, is_bandwidth_authority=False)[source]


Tor directory authority, a special type of relay hardcoded into tor to enumerate the relays in the network.

Changed in version 1.3.0: Added the is_bandwidth_authority attribute.

Changed in version 1.7.0: Added the orport_v6 attribute.

Deprecated since version 1.7.0: The is_bandwidth_authority attribute is deprecated and will be removed in the future.

Variables:v3ident (str) -- identity key fingerprint used to sign votes and consensus
static from_cache()[source]
static from_remote(timeout=60)[source]
class, or_port=None, dir_port=None, fingerprint=None, nickname=None, has_extrainfo=False, orport_v6=None, header=None)[source]


Particularly stable relays tor can instead of authorities when bootstrapping. These relays are hardcoded in tor.

For example, the following checks the performance of tor's fallback directories...

import time
from stem.descriptor.remote import get_consensus
from import Fallback

for fallback in Fallback.from_cache().values():
  start = time.time()
  get_consensus(endpoints = [(fallback.address, fallback.dir_port)]).run()
  print('Downloading the consensus took %0.2f from %s' % (time.time() - start, fallback.fingerprint))
% python
Downloading the consensus took 5.07 from 0AD3FA884D18F89EEA2D89C019379E0E7FD94417
Downloading the consensus took 3.59 from C871C91489886D5E2E94C13EA1A5FDC4B6DC5204
Downloading the consensus took 4.16 from 74A910646BCEEFBCD2E874FC1DC997430F968145

New in version 1.5.0.

Changed in version 1.7.0: Added the has_extrainfo and header attributes which are part of the second version of the fallback directories.

  • has_extrainfo (bool) -- True if the relay should be able to provide extrainfo descriptors, False otherwise.
  • header (collections.OrderedDict) -- metadata about the fallback directory file this originated from
static from_cache(path='/home/stem/stem/stem/cached_fallbacks.cfg')[source]
static from_remote(timeout=60)[source]