How to Implement Network Anonymity in NS2
To implement the Network Anonymity within NS2, which contains making a network architecture in which the identities of the participants (nodes) are concealed or obscured. It is a main characteristics in secure communication systems like an anonymous routing protocols (e.g., Onion Routing, Tor) or Mix Networks that the aim is to avoid the adversaries from detecting the sender, receiver, or the path used for communication. The following is a step-by-step procedure to execute the Network Anonymity in NS2:
Step-by-Step Guide to Implement Network Anonymity in NS2
- Define a Network Topology:
- Initially, make a network topology in which nodes can communicate using anonymized paths. It can be contained several routers or intermediate nodes, which relay traffic to hide the source and end of the communication.
Example OTcl script for a basic network topology:
set ns [new Simulator]
set nf [open out.tr w]
$ns trace-all $nf
set namfile [open out.nam w]
$ns namtrace-all $namfile
# Create nodes
set node0 [$ns node] ;# Sender (Anonymous)
set node1 [$ns node] ;# Relay node 1
set node2 [$ns node] ;# Relay node 2
set node3 [$ns node] ;# Receiver (Destination)
# Create links between nodes
$ns duplex-link $node0 $node1 1Mb 10ms DropTail ;# Sender to Relay 1
$ns duplex-link $node1 $node2 1Mb 10ms DropTail ;# Relay 1 to Relay 2
$ns duplex-link $node2 $node3 1Mb 10ms DropTail ;# Relay 2 to Receiver
# Run the simulation
$ns at 6.0 “finish”
proc finish {} {
global ns nf namfile
$ns flush-trace
close $nf
close $namfile
exec nam out.nam &
exit 0
}
$ns run
- This simple topology replicates the situation in which the sender interacts with the receiver via two relay nodes (node1 and node2) to anonymize the communication path.
- Set Up Anonymous Routing Mechanism:
- Anonymous Routing is critical to conceal the sender’s and receiver’s identities. Single path to attain it is by relaying the traffic via a sequences of intermediary nodes, as seen in Tor (Onion Routing) or Mix Networks.
Example OTcl script for onion routing-like behavior:
# Define anonymous routing (e.g., Onion Routing simulation)
proc anonymous_routing {src dst relay1 relay2} {
puts “Sender $src sends packet to Relay 1 $relay1”
$src route-to $relay1
puts “Relay 1 forwards packet to Relay 2 $relay2”
$relay1 route-to $relay2
puts “Relay 2 forwards packet to destination $dst”
$relay2 route-to $dst
}
# Simulate anonymous routing from sender to receiver via relays
$ns at 1.0 “anonymous_routing $node0 $node3 $node1 $node2”
- This replicates anonymous routing by forcing the packets to be routed via two relays before attaining the end, so concealing the origin and end from direct observation.
- Add Encryption (Optional):
- To improve the anonymity, we can replicate the encryption at every relay node. In practice, it could be included each relay decrypting a layer of encryption, same to how Onion Routing works.
Example OTcl script for encrypted relaying:
# Simulate encryption at each relay
proc encrypt_packet {src dst} {
puts “Encrypting packet at $src for next hop $dst”
# Simulate encryption (for simplicity, just log the event)
}
# Add encryption at each relay
proc anonymous_routing_with_encryption {src dst relay1 relay2} {
encrypt_packet $src $relay1
puts “Sender $src sends encrypted packet to Relay 1 $relay1”
$src route-to $relay1
encrypt_packet $relay1 $relay2
puts “Relay 1 forwards encrypted packet to Relay 2 $relay2”
$relay1 route-to $relay2
encrypt_packet $relay2 $dst
puts “Relay 2 forwards encrypted packet to destination $dst”
$relay2 route-to $dst
}
# Simulate encrypted anonymous routing
$ns at 1.0 “anonymous_routing_with_encryption $node0 $node3 $node1 $node2”
- This script replicates the encryption at each hop, and creating it harder for an observer to establish the last destination or origin of the packet.
- Log Network Events for Analysis:
- To examine how anonymity performs, we can record the packet transmission events to know how packets are move via the network and whether the anonymity mechanism is working as expected.
Example OTcl script to log network events:
# Log when packets are sent and received at each node
proc log_anonymity_event {node event} {
puts “Node $node event: $event”
}
# Log events at each relay and destination
$ns at 1.5 “log_anonymity_event $node1 Received”
$ns at 2.0 “log_anonymity_event $node2 Forwarded”
$ns at 2.5 “log_anonymity_event $node3 Received”
- This records events at the relay and end nodes to monitor the performance of the anonymous packet transmission.
- Measure Anonymity Metrics:
- In an anonymous network, a few vital metrics to estimate contain the path length (number of relays), latency (increased due to multiple relays), and packet delivery ratio.
Example AWK script to calculate average path length:
awk ‘{
if ($1 == “r” && $4 == “TCP”) {
hop_count[$11]++
}
} END {
total_hops = 0
for (i in hop_count) {
total_hops += hop_count[i]
}
print “Average Path Length: “, total_hops / NR
}’ out.tr
- This script estimates the average path length by counting how many relays, each packet passes before reaching its destination.
- Simulate Attacks on Anonymity (Optional):
- To calculates the robustness of the anonymity mechanism, we can be replicated the attacks like traffic analysis or timing attacks in which the adversaries try to imply the sender or receiver.
Example OTcl script to simulate traffic analysis:
# Adversary monitors traffic patterns at relay nodes
proc traffic_analysis_attack {relay} {
puts “Adversary monitoring traffic at relay $relay”
# Simulate adversary collecting traffic statistics
}
# Launch traffic analysis attack at Relay 1
$ns at 1.5 “traffic_analysis_attack $node1”
- This mimics an adversary trying to assess the traffic at a relay node to infer who is communicating.
- Run the Simulation and Analyze Results:
- Run the simulation to observe how anonymous communication performs in the network and monitor how packets are relayed via intermediate nodes whereas hiding their true sources and destinations.
To run the simulation:
ns your_script.tcl
- Estimate the trace files (out.tr) to check whether the anonymity mechanisms are executing as expected.
- Visualize the Network in NAM:
- We can be used the NAM (Network Animator) to envision the anonymous communication in real-time, monitoring how packets are flow via several relays.
To introduce the NAM:
nam out.nam
- In NAM, we can monitor how packets are anonymized by being relayed via intermediary nodes, and concealing the real origin and end.
Lastly, we explained the details and included examples of implementing and evaluating the Network Anonymity in NS2, as per the above outlined process. More informations will be also supplied if necessary.
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