This add-on uses the Stem Tor control port library to connect to a Tor control
port listening on port 9051 (or on an alternate user-specified port, or UNIX
file system socket).

This addon protects against guard discovery and related traffic analysis
attacks. A guard discovery attack enables an adversary to determine the guard
node(s) that are in use by a Tor client and/or Tor onion service. Once the guard
node is known, traffic analysis attacks that can deanonymize an onion service
(or onion service user) become easier.

WWW: https://github.com/mikeperry-tor/vanguards