12,985 research outputs found
Defending Tor from Network Adversaries: A Case Study of Network Path Prediction
The Tor anonymity network has been shown vulnerable to traffic analysis
attacks by autonomous systems and Internet exchanges, which can observe
different overlay hops belonging to the same circuit. We aim to determine
whether network path prediction techniques provide an accurate picture of the
threat from such adversaries, and whether they can be used to avoid this
threat. We perform a measurement study by running traceroutes from Tor relays
to destinations around the Internet. We use the data to evaluate the accuracy
of the autonomous systems and Internet exchanges that are predicted to appear
on the path using state-of-the-art path inference techniques; we also consider
the impact that prediction errors have on Tor security, and whether it is
possible to produce a useful overestimate that does not miss important threats.
Finally, we evaluate the possibility of using these predictions to actively
avoid AS and IX adversaries and the challenges this creates for the design of
Tor
Assessing the geographic resolution of exhaustive tabulation for geolocating Internet hosts
peer reviewedGeolocation of Internet hosts relies mainly on exhaustive tabulation
techniques. Those techniques consist in building a database, that keeps the mapping
between IP blocks and a geographic location. Relying on a single location
for a whole IP block requires using a coarse enough geographic resolution. As
this geographic resolution is not made explicit in databases, we try in this paper
to better understand it by comparing the location estimates of databases with a
well-established active measurements-based geolocation technique.
We show that the geographic resolution of geolocation databases is far coarser
than the resolution provided by active measurements for individual IP addresses.
Given the lack of information in databases about the expected location error
within each IP block, one cannot havemuch confidence in the accuracy of their location
estimates. Geolocation databases should either provide information about
the expected accuracy of the location estimates within each block, or reveal information
about how their location estimates have been built, unless databases have
to be trusted blindly.FP6-FET ANA (FP6-IST- 27489
Is Explicit Congestion Notification usable with UDP?
We present initial measurements to determine if ECN is usable with
UDP traffic in the public Internet. This is interesting because ECN
is part of current IETF proposals for congestion control of UDPbased
interactive multimedia, and due to the increasing use of UDP
as a substrate on which new transport protocols can be deployed.
Using measurements from the author’s homes, their workplace,
and cloud servers in each of the nine EC2 regions worldwide, we
test reachability of 2500 servers from the public NTP server pool,
using ECT(0) and not-ECT marked UDP packets. We show that
an average of 98.97% of the NTP servers that are reachable using
not-ECT marked packets are also reachable using ECT(0) marked
UDP packets, and that ~98% of network hops pass ECT(0) marked
packets without clearing the ECT bits. We compare reachability of
the same hosts using ECN with TCP, finding that 82.0% of those
reachable with TCP can successfully negotiate and use ECN. Our
findings suggest that ECN is broadly usable with UDP traffic, and
that support for use of ECN with TCP has increased
An Overview of Internet Measurements:Fundamentals, Techniques, and Trends
The Internet presents great challenges to the characterization of its structure and behavior. Different reasons contribute to this situation, including a huge user community, a large range of applications, equipment heterogeneity, distributed administration, vast geographic coverage, and the dynamism that are typical of the current Internet. In order to deal with these challenges, several measurement-based approaches have been recently proposed to estimate and better understand the behavior, dynamics, and properties of the Internet. The set of these measurement-based techniques composes the Internet Measurements area of research. This overview paper covers the Internet Measurements area by presenting measurement-based tools and methods that directly influence other conventional areas, such as network design and planning, traffic engineering, quality of service, and network management
Jumps: Enhancing hop-count positioning in sensor networks using multiple coordinates
Positioning systems in self-organizing networks generally rely on
measurements such as delay and received signal strength, which may be difficult
to obtain and often require dedicated equipment. An alternative to such
approaches is to use simple connectivity information, that is, the presence or
absence of a link between any pair of nodes, and to extend it to hop-counts, in
order to obtain an approximate coordinate system. Such an approximation is
sufficient for a large number of applications, such as routing. In this paper,
we propose Jumps, a positioning system for those self-organizing networks in
which other types of (exact) positioning systems cannot be used or are deemed
to be too costly. Jumps builds a multiple coordinate system based solely on
nodes neighborhood knowledge. Jumps is interesting in the context of wireless
sensor networks, as it neither requires additional embedded equipment nor
relies on any nodes capabilities. While other approaches use only three
hop-count measurements to infer the position of a node, Jumps uses an arbitrary
number. We observe that an increase in the number of measurements leads to an
improvement in the localization process, without requiring a high dense
environment. We show through simulations that Jumps, when compared with
existing approaches, reduces the number of nodes sharing the same coordinates,
which paves the way for functions such as position-based routing
- …