Presentation

Performane Analysis Of The CONFIDANT
Protocol (Cooperation Of Nodes :Fairness In
Dynamic Ad-hoc Networks)
Hamza Hammami
12 décembre 2012
Hamza Hammami
Performane Analysis Of The CONFIDANT Protocol

Introduction
The Condant protocol works as an extension to a reactive
source routing protocol for mobile ad-hoc networks.
CONFIDANT aims at making misbehavior in mobile ad hoc
networks unattractive. It is based on selective altruism and
utilitarianism.
We present a performance analysis of DSR fortied by
CONFIDANT and compare it to regular defenseless DSR.
Hamza Hammami

The DSR Protocol
The DSR Protocol it is a protocol developed for routing in a
mobile ad-hoc networks.
After receiving routes, the source node selects the best, stores
it and sends messages along that path.
A link failure is detected by a node that cannot forward the
packet to the next node in the source route. It then sends a
ROUTE ERROR message to the source.
Packets are then forwarded along an alternate route that does
not contain the bad link.
Hamza Hammami

Attacks against routing
The lack of infrastructure of mobile ad-hoc networks oer special
chance to attacks.We should provide a proper security to protect
against the following attacks :
No Forwarding(of control message of data).
Trac deviation(advertises manu excellent routes or advertises
routes very rapidly so they are deemend good routes).
Route salvaging.
Lack of error messages.
Unusually frequent route updates.
Hamza Hammami

Thwarting Attack
The aim is prevention ,We should provide perfect mechanism.Most
attacks have been the result of by passing prevention mechanisms.
We propose a method based on detection of misbehavior,We
need a reasonable power consumption.
We propose that packets of malicious nodes should not be
forworded by normally behaving nodes.it is disavantageous for
nodes to behave maliciouly
Hamza Hammami

Selsh Gene
The selsh gene Richard explains , there is an intrinsic motivation
for cooperation because of instatnt gratication.The benet of
behaving well is not abvious when there is delay between granting a
favor and the repayment.
According to dowkins , simulation has shown when starting
with a majority population of cheats and marginal group of
both suckers and grudgers , the grudgers win overtime.
Once the suckers are extinct,the grudgers grow rapidly at the
expense of the cheats , because they do not help a cheat twice.
Hamza Hammami

Selsh Gene
In a very large ad-hoc network , convergence can be very show
and keeping a history of all bad experiences with other
nodes,therefore we propose the following ideas :
Learn from observed behaviour :employ 'neighborhood
watch'to be warned by observing what happens to other nodes
in the neighborhood,before having to make a bad experience
oneself.
Learn from reported behaviour :share information of
experienced malicious behavior with friends and also learn from
them.
Hamza Hammami

CONFIDANT COMPONENTS
We now describe the components of CONFIDANT, assumed to be
present in every node :
The Monitor
The Reputation System
The Path Manager
The Trust Manager
Hamza Hammami

The Monitor :
One approach to protocol enforcement and detection of
damaging behaviour suggested here is equivalent of a
neighborhood watch,where nodes locally look for deviating
nodes.
The Monitor registers these deviations from normal
behaviour.As soon as a given bad behaviour occurs , the
reputation system is called.
Hamza Hammami

The Trust Manager :this component deals with incoming and
outgoing ALARM messages.
ALARM messages are sebt by the trust manager of a node to
warn others of malicious nodes .
Outgoing alarms are sent by a node to its friends after having
experienced, observed or received a report of malicious
behavior.
Incoming alarms originate from either outside friends or other
nodes, so the source of an alarm has to be checked for
trustworthiness before triggering a reaction.
Hamza Hammami

A mechanism similar to the trust management in PGP is used
here for determining if there is enough trusted evidence for the
misbehavior of a node.
The Trust Manager consists of the following components :
An alarm table containing information about received alarms.
A trust table managing trust levels for nodes to determine the
trustworthiness of an alarm.
A friends list containing all friends a node potentially sends
alarms to.
Hamza Hammami

The Reputation system in this protocol manages a table
consisting of entries for nodes and their rating.The rating is then
changed according to a rate function that assigns dierent weights
to the type of behavior detection , namely the greatest weight for
own experience . Once the weight has been determined the entry of
the node that misbehaved is changed accordingly.
Hamza Hammami

The Path Manager performs the following :
Path re-ranking according to security metric,such as reputation
of nodes in the path.
Deletion of oaths containing malicious nodes.
Action on receiving a request for a route from a malicious
node .
Hamza Hammami

Protocol Description : what constitutes the signicant rating can
be dened for dierent types of nodes according to their security
requirements.If the occurence theshold is exeeded ,The Reputation
System Updates the rating of the node that caused the event .In
order to convey warming information,an ALARM message is sent by
the Trust Manager.
Hamza Hammami

How the components functions
The Monitor of each node evaluates, on the basis of its
observations, the behavior nodes in respect of the routing function.
Once the monitor detects a suspicious event, it sends information
to the system reputation.
The latter update maintains reputation values ratings of each node
observed. To remedy the imprecision of detection mechanisms and
a system that converges faster, Condant uses the principle of
mutual recommendations between network nodes.
Hamza Hammami

This role is played by the trust manager who takes care of a part,
the decision to make regarding the sharing of reputation values and
secondly, the how to aggregate all the recommendations received.
Condant considers only negative recommendations.
Hamza Hammami

Finally, the path manager is used in the order to select the optimal
path in terms of reliability of the nodes that compose and may
decide not to route packets nodes with notes reputation global
below the tolerated by the system.
Hamza Hammami

Performance Analysis
We present a performance analysis of( DSR )fortied by
CONFIDANT ,The aim of this performance analysis is to determine
the impact of the CONFIDANT routing protocol extensions on
metrics.The regular DSR protocol is used as a reference .
Our goal is also to learn how protocol parameters such as
thresholds should be set.
The Metrics used are Goodput, Overhead and Utility.
Goodput(G) = Total packets received/ Total packets
originated
Hamza Hammami

for the performance analysis ,the metrics are observed in various
network .The rst network we analyse is a reguler well behaved
DSR network which is used as a refernce.The second enhancement
is to include the case when the neighbor node fails to forward a
packet for some other node and it is detected.
In the simulation,every benign node is a friend of the source and
informs the source when packets are maliciously dropped by the
next hope.
Hamza Hammami

Simulation Results :in the defenseless network ,the number of
packets dropped intentionally is up to two orders of magnitude
greater than in the network fortied by condant.When looking at
the number dropped from a network size perspective ,it can be seen
from gure 3 that the dierence in performance increases with the
total number of nodes in the network.
Hamza Hammami

Estimation of factor Relevance :the choice for the number of
nodes was made with the intention to show both a very small
network that still allows for multiple paths and reasonable network
connectivity given the area and a larger network to get insights on
scalability.
The extreme levels for the percentage of malicious nodes in the
network population are motivated by the desire to show the
behavior of a network.
This can be explained by the fact that the number of packets
dropped in a fortied network in the presence of one third malicious.
Hamza Hammami

Future Work
The threshold value used to change a node's rating.
Methods to eciently distribute reputation information to
avoid malicious nodes as early as possible.
CONFIDANT assumes that nodes are authenticated and that
no node can pretend to beanother.If a node is compromised
then it could send ALARMs about a benign node to its
neighbors and propagate this by pretending to be another
node.
Hamza Hammami

Conclusion
Mobile ad-hoc networks shows new vulnerabilities to malicious
attacks .So special care has to be taken to include fairness
mechanisms.Obserable attacks on forwarding and routing in mobile
ad-hoc networks can be thwarted by the suggested CONFIDANT
scheme of detection.
The CONFIDANT Protocol is scalable in terms of total number of
nodes in a network and performs well event with a fraction of
malicious nodes.
Hamza Hammami

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