Download Secure Routing with AODV Protocol for Mobile Ad Hoc Network

Secure Routing with AODV
Protocol for Mobile Ad Hoc
Networks
Anitha Prahladachar
Tahira Farid
Course: 60-564
Instructor: Dr. Aggarwal
Papers Reviewed
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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
Outline
Mobile Ad Hoc Networks (MANET)
 Applications
 Security Design Issues in MANET
 Motivation
 Traditional AODV
 Secured AODV
 Experimental Comparisons
 Closing Remarks
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Mobile Ad Hoc Networks
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A collection of wireless mobile hosts forming a
temporary network without the aid of any
established infrastructure.
Significant Features:
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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
Mobile Ad Hoc Networks (cont.)
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The network topology can change any time
because of node mobility and nodes may become
disconnected very frequently.
Mobile Ad Hoc Networks (cont.)
Routing: Source -> Destination
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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.
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

Security Design Issues in MANET

Do not have any centrally administered
secure routers.
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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.
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Motivation
Ad Hoc networks are challenged due to
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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.
Traditional AODV
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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:
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used to determine local connectivity.
can reduce response time to routing requests.
can trigger updates when necessary.
Traditional AODV – Route Discovery
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If a source needs a route to a destination for which it does
not already have a route in its cache:
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Source broadcasts Route Request (RREQ)
message for specified destination
Intermediate node:
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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…)
Traditional AODV – RREQ
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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_#
Traditional AODV (RREQ)
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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.
Traditional AODV (RREP)
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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
Dest_addr
Dest_sequence_#
Source_addr
lifetime
hopcnt
Traditional AODV (RREP)
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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.
Approach 1 : Secure AODV
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Vulnerability issues of AODV (due to
intermediate nodes):
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Deceptive incrementing of sequence number
Deceptive decrementing of hop count
To secure AODV, approach 1 divided
security issues into 3 categories:
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Key Exchange
Secure Routing
Data Protection
Approach 1 : Secure AODV (cont.)
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Key Exchange:
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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.
Approach 1 : Secure AODV (cont.)
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Secure Routing (RREQ):
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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.
Approach 1 : Secure AODV (cont.)
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Secure Routing (RREP)
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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’.
Approach 1 : Secure AODV (cont.)
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Data Protection
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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.
Security Analysis for Approach 1
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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.
Approach 2: Secure AODV (cont.)
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Defines two types of attacks:
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Internal & external
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Compromised & Selfish nodes
Malicious nodes
To handle the attacks, this approach
suggests two models:
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Intrusion Detection Model (IDM)
Intrusion Response Model (IRM)
Approach 2: Secure AODV (cont.)
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Vulnerability issues of AODV (due to
internal attacks):
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Distributed false route request
Denial of service
Destination is compromised
Impersonation
Approach 2: Secure AODV (cont.)
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IDM
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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
Approach 2: Secure AODV (cont.)
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IDM
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Distributed False Route Request
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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.
Approach 2: Secure AODV (cont.)
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IDM
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Denial of Service
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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.
Approach 2: Secure AODV (cont.)
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IDM - Destination is Compromised
A destination might not reply if it is:
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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.
Approach 2: Secure AODV (cont.)
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IDM
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Impersonation
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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.
Approach 2: Secure AODV (cont.)
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Intrusion Response Model ( IRM )
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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.
Approach 3: Secure AODV
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SAODV
Vulnerability issues of AODV:
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Message Tampering Attack [compromised node]
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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:
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Source Authentication
Neighbor Authentication
Message Integrity
Access Control
Approach 3: Secure AODV (cont.)
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Source Authentication
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Neighbor Authentication
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Receiver should be able to confirm the identify of the
sender (one-hop previous node)
Message Integrity
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Receiver should be able to confirm the identity of the
source.
Receiver should be able to verify that content of a
message has not be altered either maliciously or
accidentally in transit.
Access Control
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It is necessary to ensure that mobile nodes seeking to
gain access to the network have the appropriate access
rights.
Approach 3: Secure AODV (cont.)
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Route Discovery
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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 = hMHCHop_Count(Hash).
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Before rebroadcasting RREQ, increments hop-count
field by 1 in RREQ header.
Computes new Hash value by hashing the old value,
h(Hash).
Approach 3: Secure AODV (cont.)
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Route Discovery
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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.
Experimental Comparisons
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Between AODV and
SAODV
Indoor Experiments
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10 laptops are placed in
the same room
Facilitates the comparison
of ns-2 simulation and
indoor emulation results.
Outdoor Experiments
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Conducted in a rugby field
(250m – 100m approx.).
Participants with laptop
walked randomly at
1m/sec.
Each test run took 6 mins.
Experimental Comparisons (Results and
Discussions)
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Indoor Emulation and Simulation Results
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UDP Traffic – UDP Packet Delivery Ratio
Experimental Comparisons (Results and
Discussions)
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Indoor Emulation and Simulation Results
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UDP Traffic – Routing Control Overhead (in packets)
Experimental Comparisons (Results and
Discussions)
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Indoor Emulation and Simulation Results
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UDP Traffic – Routing Control Overhead (in bytes)
Experimental Comparisons (Results and
Discussions)
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Outdoor Results
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UDP Packet Delivery Ratio
Routing Control overhead for
UDP
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Amount of Routing Packets
Aggregate Routing Overhead
Closing Remarks
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Approach 1
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Approach 2
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Authors proposed Approach 1 for both secure routing and data
protection
No Experiments have been discussed.
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
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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.
Thank you!!!
Questions???