Secure Routing with AODV Protocol for MANET by Ashok Panwar

Secure Routing with AODV
Protocol for Mobile Ad Hoc
Networks (MANET’s)
Presented by:-
Ashok Panwar
Technical Officer in ECIL (NPCIL)
Tarapur , Mumbai.

Papers Reviewed
 Perkins, C.E.; Royer, E.M,”Ad-hoc On-Demand Distance Vector
Routing,” Proceedings of the Second IEEE Workshop on Mobile
Computing Systems and Applications, WMCSA ’99
 Pirzada, A.A.; McDonald, C,”Secure Routing with the AODV Protocol,”
Proceedings of the Asia-Pacific Conference on Communications, Oct 3-5,
2005
 Bhargava, S.; Agrawal, D.P.,”Security Enhancements in AODV protocol
for Wireless Ad Hoc Networks,” Vehicular Technology Conference Oct 7-
11, 2004, IEEE VTS 54th Vol. 4
 Yuxia Lin, A. Hamed Mohsenian Rad, Vincent W. S. Wong, Joo-Han
Song,”Experimental Comparisons between SAODV and AODV Routing
Protocols,” Proceedings of the 1st ACM workshop on Wireless Multimedia
Networking and Performance modeling, WMuNeP Oct 2005
2
Presented by:- Ashok Panwar
Technical Officer in ECIL

Outline
 Mobile Ad Hoc Networks (MANET)
 Applications
 Security Design Issues in MANET
 Motivation
 Traditional AODV
 Secured AODV
 Experimental Comparisons
 Closing Remarks
3

Mobile Ad Hoc Networks
 A collection of wireless mobile hosts forming a temporary network without the
aid of any established infrastructure.
 Significant Features:
 Dynamic topology of interconnections
 No administrator
 Short transmission range- routes between nodes has one or more hops
 Nodes act as routers or depend on others for routing
 movement of nodes invalidates topology information
4

Mobile Ad Hoc Networks (cont.)
 The network topology can change any time because of node
mobility and nodes may become disconnected very frequently.
5

Mobile Ad Hoc Networks (cont.)
 Host A and C are out of range from each other’s wireless transmitter.
 While exchanging packets, they use routing services of host B.
 B is within the transmission range of both of them.
Routing: Source -> Destination
6

Applications of MANET
 Useful where geographical or terrestrial constrains
demand totally distributed network without fixed base
station.
 Military Battlefields
 Disaster and Rescue Operations
 Conferences
 Peer to Peer Networks
7

Security Design Issues in MANET
 Do not have any centrally administered secure
routers.
 Attackers from inside or outside can easily exploit the
network.
 Passive eavesdropping, data tampering, active interfering,
leakage of secret information, DoS etc.
 Open peer-to-peer architecture.
 Shared Wireless Medium.
 Dynamic Topology.
8

Motivation
Ad Hoc networks are challenged due to
 Nodes are constantly mobile
 Protocols implemented are co-operative in nature
 Lack of fixed infrastructure and central concentration point where IDS
can collect audit data
 One node can be compromised in a way that the incorrect and
malicious behaviour cannot be directly noted at all.
 Well-established traditional security approaches to routing are
inadequate in MANET.
9

Traditional AODV
 Ad Hoc On Demand Distance Vector Routing Protocol
 Reactive Protocol: discovers a route on demand.
 Nodes do not have to maintain routing information.
 Route Discovery
 Route Maintenance
 Hello messages:
 used to determine local connectivity.
 can reduce response time to routing requests.
 can trigger updates when necessary.
10

Traditional AODV – Route Discovery
 If a source needs a route to a destination for which it does not already have
a route in its cache:
 Source broadcasts Route Request (RREQ) message for
specified destination
 Intermediate node:
 Returns a route reply packet (RREP) (if route information about
destination in its cache), or
 forwards the RREQ to its neighbors (if route information about
destination not in its cache).
 If cannot respond to RREQ, increments hop count, saves info to
implement a reverse path set up, to use when sending reply
(assumes bidirectional link…)
11

Traditional AODV – RREQ
 RREQ packet contains: destination
and source IP address, broadcast ID,
source node’s sequence number and
destination node’s sequence number.
 Node 1 wants to send data packet to node
7. Node 6 knows a current route to node
7. Node 1 sends a RREQ packet to its
neighbors.
Source_addr =1
dest_addr =7
broadcast_id = broadcast_id +1
source_sequence_# =
source_sequence_# + 1
dest_sequence_# = last dest_sequence_#
for node 7
Type Flag Resvd hopcnt
Broadcast_id
Dest_addr
Dest_sequence_#
Source_addr
Source_Sequence_#
12

Traditional AODV (RREQ)
 Nodes 2 and 4 verify that this is a new RREQ (source_sequence_# is not stale) with
respect to the reverse route to node 1.
 Forward the RREQ, and increment hop_cnt in the RREQ packet.
 RREQ reaches node 6 from node 4, which knows a route to 7.
 Node 6 verify that the destination sequence number is less than or equal to the
destination sequence number it has recorded for node 7.
 Nodes 3 and 5 will forward the RREQ packet to node 6, but it recognizes the
packets as duplicates.
13

Traditional AODV (RREP)
 Node 6 has a route to destination. It sends a route reply RREP to the
neighbor that sent the RREQ packet.
 Intermediate nodes propagate RREP towards the source using cached
reverse route entries.
 Other RREP packets discarded unless, dest_seq_# is higher than the
pervious, or same but hop_cnt is smaller.
 Cached reverse routes timeout in nodes that do not see RREP packet.
Type Flag prsz hopcnt
Dest_addr
Dest_sequence_#
Source_addr
lifetime
14

Traditional AODV (RREP)
 Node 6 sends RREP to node 4
 Source_addr=1, dest_addr=7, dest_sequence_# = maximum (sequence no.
stored for node 7, dest_sequence_# in RREQ), hop_cnt =1.
 Node 4 finds out it is a new route reply and propagates the RREP packet to
Node 1.
15

Approach 1 : Secure AODV
 Vulnerability issues of AODV (due to intermediate
nodes):
 Deceptive incrementing of sequence number
 Deceptive decrementing of hop count
 To secure AODV, approach 1 divided security issues
into 3 categories:
 Key Exchange
 Secure Routing
 Data Protection
16

Approach 1 : Secure AODV (cont.)
 Key Exchange:
 All nodes before entering the network procure a one-time
public and private key pair from CA and CA’s public key.
 After that, nodes can generate a Group Session Key
between immediate neighbors using a suitable ‘Group
keying protocol’.
 These session keys are used for securing the routing
process and data flow.
 Thus authentication, confidentiality and integrity is
assured.
17

 Secure Routing (RREQ):
 Node ‘x’ desiring to establish communication with ‘y’, establishes a group session key
Kx between its immediate neighbors.
 Creates RREQ packet, encrypts using Kx and broadcasts.
 Intermediate recipients that share Kx decrypt RREQ and modify.
 Intermediate nodes that do not share Kx initiate ‘group session key exchange protocol’
with the immediate neighbors.
 Intermediate nodes encrypt RREQ packet using the new session key and rebroadcast.
18

 Secure Routing (RREP)
 In response to RREQ, ‘y’ creates RREP.
 RREP is encrypted using the last Group session key that
was used to decrypt RREQ and is unicast back to the
original sender.
 If any of the intermediate nodes has moved out of wireless
range, a new group session key is established.
 Recipient nodes that share the forward group session key
decrypt RREP and modify.
 RREP is then encrypted using backward group session key
and unicast to ‘x’.
19

 Data Protection
 Node ‘x’ desiring to establish end-to-end secure data channel, first establishes
a session key Kxy with ‘y’.
 ‘x’ symmetrically encrypts the data packet using Kxy and transmits it over the
secure route.
 Intermediate nodes forward the packet in the intended direction.
 Node ‘y’ decrypts the encrypted data packet using Kxy.
20

Security Analysis for Approach 1
 Authorized nodes to perform route computation and discovery.
 Routing control packets authenticated and encrypted by each
forwarding node.
 Minimal exposure of network topology.
 Routing information is encrypted, an adversary will gain no
information on the network topology.
 Detection of spoofed routing messages.
 Initial authentication links a number of identities to each node’s private
key.
 Detection of fabricated routing messages.
 To fabricate a routing message session key needs to be compromised.
 Prevent redirection of routes from shortest paths.
 Routing packets accepted only from authenticated nodes, adversary
cannot inject anything unless an authorized node first authenticates it.
21

Approach 2: Secure AODV (cont.)
 Defines two types of attacks:
 Internal & external
 Compromised & Selfish nodes
 Malicious nodes
 To handle the attacks, this approach suggests two
models:
 Intrusion Detection Model (IDM)
 Intrusion Response Model (IRM)
22

 Vulnerability issues of AODV (due to internal
attacks):
 Distributed false route request
 Denial of service
 Destination is compromised
 Impersonation
23

 IDM
 Each node employs IDM that
utilizes the neighborhood
information to detect
misbehaviors of its neighbors.
 When Misbehavior count >
threshold for a node, information
is sent to other nodes about
misbehaving node.
 They in turn check their local
MalCount, and add the result to
the initiator’s response.
 IDM is present on all the nodes
and monitors and analyzes
behavior of its neighbors to
detect if any node is
compromised.
Secure Communication
Global Response
Intrusion Response Model
(IRM)
Mal
Count
>
Threshol
d
Intrusion Detection Model
(IDM)
Data Collection
24

 IDM
 Distributed False Route Request
 Malicious node may generate frequent unnecessary
route requests i.e. false route message.
 If done from different radio range it is difficult to
identify the malicious node (RREQ are broadcasts).
 When a node receives RREQ > threshold count by a
specific source for a destination in a particular time
interval- tinterval, the node is declared malicious.
25

 IDM
 Denial of Service
 A malicious node may launch DoS attack by
transmitting false control packets and using the entire
network resources.
 Other nodes are deprived of these resources.
 It can be identified if a node is generating the control
packets that is more than threshold count in a particular
time interval – tfrequency.
26

 IDM - Destination is Compromised
 A destination might not reply if it is:
 Not in the network
 Overloaded
 Did not receive route request
 Malicious
 It is identified when a source does not receive reply from
destination in a particular time interval – twait.
 Neighbors generate ‘Hello’ packets to determine connectivity.
 If a node is in network and does not respond to RREQ
destined for it, it is identified as malicious.
27

IDM
 Impersonation
If Sender encrypts the packet with its private
key and other nodes decrypt with public key of
sender , this attack can be avoided.
If Receiver is not able to decrypt the packet, the
sender might not be the real source and packet
will be dropped.
28

 Intrusion Response Model ( IRM )
 A node ‘x’ identifies that another node ‘m’ is compromised when
malcount for that node ‘m’ increases beyond threshold value.
 ‘x’ propagates to entire network by transmitting ‘Mal’ packet.
 If another node ‘y’ suspects node ‘m’, it reports its suspicion to the
network and transmits ‘ReMal’ packet.
 If two or more nodes report about a particular node , ‘Purge’ packet is
transmitted to isolate malicious node from the network.
 All nodes having a route through the compromised node look for
newer routes.
 All packets received from the compromised node are dropped.
29

Approach 3: Secure AODV
 SAODV
 Vulnerability issues of AODV:
 Message Tampering Attack [compromised node]
 E.g. Hop count made 0 by attacker node
 E.g. Hop count made infinite by selfish node.
 Message Dropping Attack [selfish node]
 Message Replay (wormhole) Attack [malicious node]
 Security Requirements for AODV:
 Source Authentication
 Neighbor Authentication
 Message Integrity
 Access Control
30

 Source Authentication
 Receiver should be able to confirm the identity of the source.
 Neighbor Authentication
 Receiver should be able to confirm the identify of the sender (one-hop
previous node)
 Message Integrity
 Receiver should be able to verify that content of a message has not be
altered either maliciously or accidentally in transit.
 Access Control
 It is necessary to ensure that mobile nodes seeking to gain access to the
network have the appropriate access rights.
31

 Route Discovery
 Source node selects a random seed number & sets
Maximum hop-count (MHC) value.
 Using hash function h, source computes hash value as
h(seed) and Top_Hash as hMHC
(seed).
 Intermediate node checks if Top_Hash = hMHC-Hop_Count
(Hash).
 Before rebroadcasting RREQ, increments hop-count field by 1 in
RREQ header.
 Computes new Hash value by hashing the old value, h(Hash).
32

 Route Discovery
 Except for hop-count field and hhop-count
(seed), all
other fields of RREQ are non-mutable.
 Hence can be authenticated by verifying the
signature in RREQ.
 Destination generates RREP on receiving RREQ.
33

Closing Remarks
 Approach 1
 Authors proposed Approach 1 for both secure routing and data protection
 No Experiments have been discussed.
 Approach 2
 No Data Security Provided
 Routing load of a network increases as malicious nodes generate False Control
Messages.
 After implementing, decreases routing load by identifying malicious node and
isolating them from the network.
 Approach 3
 Ensure both integrity of data and control packets by using hash functions.
 Source, Neighbor authentication and access control are ensured by digital
signatures.
 Many indoor and outdoor experiments have been performed.
 More efficient.
34

Any Questions???
???
35

Secure Routing with AODV Protocol for MANET by Ashok Panwar

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