Hardware Reference
In-Depth Information
connection is the exit node. However, the true originator is Alice whose IP is hidden by
the Tor network.
The response to this information by many individuals is:
"So what? Why do I care if the website I'm visiting knows my IP address?"
The website, which knows the data you requested, now knows your location. This inform-
ation could be combined with other public information, for example, to conduct a
linkage
attack
. A linkage attack is an attempt at deanonymization by combining information from
multiple sources. For example, let's say you are searching for information on a rare medic-
al condition. You post a question on a forum, under a pseudonym, asking for information.
However, the website, and anybody passively monitoring your connection (if it wasn't en-
crypted), knows your general location as well as your question. Your medical condition is
most prevalent in Hispanic females in their seventies. Using your IP address combined
with knowledge about your medical condition, one can conduct a linkage attack possibly
using public census data to reveal your identity.
Tor protects against this kind of attacks by encrypting your traffic through the Tor network
and masking your IP address. To the remote website, your IP address will be that of the
last node in the Tor network, known as an exit relay.
