How to Implement Network Trust Models in NS2

To implement Network Trust Models in NS2 has series of steps to follow that includes to mimic the trustworthiness of nodes inside a network and using that information to take decisions regarding the data forwarding, interaction, and collaboration among the nodes. Trust models are specifically helpful in ad hoc networks, sensor networks, vehicular networks, and peer-to-peer (P2P) systems, in which the nodes perform maliciously or unreliably. The given below is the detailed approach to implement the network trust models in ns2:

Key Components of a Network Trust Model:

  1. Trust Calculation: Each node estimates trust for other nodes based on numerous factors like behaviour, past interactions, packet forwarding success, and reputation.
  2. Trust-based Decision Making: Nodes use trust values to decide whether to forward packets or work together with other nodes.
  3. Trust Update Mechanism: Trust values are updated enthusiastically according to the actions and behaviours of nodes.
  4. Trust Metrics: the performance metrics such as packet delivery ratio, forwarding behaviour, and direct/indirect communication are used to estimate trust.

Steps to Implement a Trust Model in NS2

  1. Define Trust Metrics: Describe parameters to estimate trust based on node behaviour like successful packet forwarding, misbehaviour, etc.
  2. Implement Trust Calculation: Apply logic to estimate the trust of each node based on communication with other nodes.
  3. Trust-based Forwarding: Use trust values to decide whether a node should forward packets or drop them.
  4. Trust Update Mechanism: execute a mechanism to enthusiastically update trust values according to ongoing communication among nodes.

Example: Simulating a Simple Trust Model in NS2

This instance will show you on how to execute a basic trust model in which nodes monitor each other’s behaviour (packet forwarding) and use trust values to decide whether to forward packets. Nodes with minimal trust values will be omitted from forwarding decisions.

Step 1: Define Nodes and Initial Trust Values

# Define the simulator object

set ns [new Simulator]

# Define trace and nam files for output

set tracefile [open out.tr w]

set namfile [open out.nam w]

$ns trace-all $tracefile

$ns namtrace-all $namfile

# Define a ‘finish’ procedure to end the simulation and visualize in NAM

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam out.nam &

exit 0

}

# Set up the topography for the simulation area

set topo [new Topography]

$topo load_flatgrid 1000 1000

# Define the wireless channel

set chan [new Channel/WirelessChannel]

# Configure wireless nodes (representing nodes in the network)

$ns node-config -adhocRouting DSDV \

-llType LL \

-macType Mac/802_11 \

-ifqType Queue/DropTail/PriQueue \

-ifqLen 50 \

-antType Antenna/OmniAntenna \

-propType Propagation/TwoRayGround \

-phyType Phy/WirelessPhy \

-channel $chan

# Create four nodes: node1, node2, node3, and node4

set node1 [$ns node]

set node2 [$ns node]

set node3 [$ns node]

set node4 [$ns node]

# Set node positions for NAM visualization

$node1 set X_ 100; $node1 set Y_ 100; $node1 set Z_ 0

$node2 set X_ 300; $node2 set Y_ 300; $node2 set Z_ 0

$node3 set X_ 600; $node3 set Y_ 600; $node3 set Z_ 0

$node4 set X_ 900; $node4 set Y_ 900; $node4 set Z_ 0

# Define initial trust values for each node

set trust_node1 1.0   ;# Full trust (1.0 = maximum trust)

set trust_node2 1.0

set trust_node3 0.5   ;# Lower trust for node3 (0.5 = moderate trust)

set trust_node4 0.2   ;# Node4 has very low trust (0.2 = low trust)

Step 2: Implement Trust Calculation and Trust-Based Forwarding

# Procedure to calculate trust based on node behavior

proc calculate_trust {node trust_value behavior} {

global ns

# Behavior: 1 (cooperative), 0 (non-cooperative or malicious)

if { $behavior == 1 } {

# Increase trust if the node cooperates (forwards packets successfully)

set new_trust [expr $trust_value + 0.1]

} else {

# Decrease trust if the node misbehaves (e.g., drops packets)

set new_trust [expr $trust_value – 0.2]

}

# Ensure trust value stays within [0.0, 1.0]

if { $new_trust > 1.0 } {

set new_trust 1.0

} elseif { $new_trust < 0.0 } {

set new_trust 0.0

}

return $new_trust

}

# Procedure for trust-based packet forwarding

proc trust_based_forward {src dst trust_value} {

if { $trust_value >= 0.5 } {

# Forward the packet if the node’s trust value is high enough (>= 0.5)

puts “Node $src forwards the packet to node $dst (trust = $trust_value)”

} else {

# Drop the packet if the node’s trust value is too low (< 0.5)

puts “Node $src drops the packet (trust = $trust_value)”

}

}

Step 3: Simulate Packet Forwarding Based on Trust

# Procedure to simulate packet forwarding between nodes

proc simulate_packet_forwarding {src dst trust_value behavior} {

# Update trust based on the node’s behavior (cooperative or malicious)

set updated_trust [calculate_trust $src $trust_value $behavior]

# Use trust-based decision making to forward or drop the packet

trust_based_forward $src $dst $updated_trust

# Return the updated trust value

return $updated_trust

}

# Step 4: Schedule Trust-Based Packet Forwarding

# Simulate cooperative behavior (1 = cooperative, 0 = non-cooperative)

set trust_node1 [simulate_packet_forwarding $node1 $node2 $trust_node1 1]  ;# Node1 cooperates

set trust_node2 [simulate_packet_forwarding $node2 $node3 $trust_node2 1]  ;# Node2 cooperates

set trust_node3 [simulate_packet_forwarding $node3 $node4 $trust_node3 0]  ;# Node3 drops packets

set trust_node4 [simulate_packet_forwarding $node4 $node1 $trust_node4 0]  ;# Node4 drops packets

Step 4: Finish the Simulation

# Schedule the end of the simulation

$ns at 10.0 “finish”

# Run the simulation

$ns run

  1. Explanation of the Script
  • Trust Calculation: The calculate_trust procedure enthusiastically updates the trust value of a node based on its features. Cooperative nodes maximize their trust value, since non-cooperative (or malicious) nodes minimize their trust value.
  • Trust-Based Forwarding: The trust_based_forward protocols decide whether to forward or drop a packet according to the node’s trust value. Nodes with trust values below a particular threshold (0.5 in this case) drop packets.
  • Dynamic Trust Update: All time a packet is dispatched or released, the trust value of the node is updated according to its characteristics (successful forwarding or misbehavior).
  1. Run the Simulation

Save the script as trust_model.tcl and execute it using:

ns trust_model.tcl

This will create a trace file (out.tr) and a NAM file (out.nam). The trace file logs the packet transmissions, and the NAM file permits to envision the trust-based packet forwarding process.

  1. Visualize the Simulation in NAM

To envvision the simulation in NAM, use the following command:

nam out.nam

In NAM, we can observe nodes forwarding or dropping packets according to their trust values.

  1. Advanced Trust Model Features
  • Indirect Trust: Execute indirect trust by permits nodes to share trust information about other nodes, so that a node can depend on others’ trust opinions.

Example:

proc share_trust_info {node1 node2 node3 trust_value} {

puts “Node $node1 shares trust information about node $node3 with node $node2”

# Node2 updates its trust of node3 based on node1’s information

set updated_trust [expr ($trust_value + 0.5) / 2.0]  ;# Average trust

return $updated_trust

}

# Share trust info between nodes

set trust_node3 [share_trust_info $node1 $node2 $node3 $trust_node3]

  • Reputation-Based Trust: Execute reputation-based trust, in which nodes gather trust based on feedback from other nodes.
  • Trust Decay: Establish trust decay over time, in which the trust values gradually minimized if nodes do not communicate for a long time.
  • Advanced Routing Protocols: Incorporate the trust model with routing protocols such as AODV or DSR in which routes are prioritized according to the reliability of intermediate nodes.

In this demonstration we get to know and gain knowledge regarding the network trust model concepts and their evaluation process to deploy in the ns2 implementation tool. We will offer more information regarding the network trust models.

We offer support for your projects involving ad hoc networks, sensor networks, vehicular networks, and peer-to-peer (P2P) systems. ns2project.com team will help you implement Network Trust Models using the NS2 tool, ensuring you achieve the best results.