How to Implement SDN Forensics in NS2

To implement Software-Defined Networking (SDN) Forensics in NS2 has includes to measure the network traffic and events especially within an SDN architecture. SDN isolates the control plane from the data plane that permits centralized control the network traffic via a controller. Executing SDN Forensics in NS2 has contain to monitoring and measuring the control plane events like rule changes, flow modifications and data plane activities such as packet forwarding, attacks to identify malicious activities or anomalies.

Below is a procedure to implement the SDN forensic in ns2:

Step-by-Step Implementation:

  1. Set up NS2 with SDN Functionality

NS2 does not natively support SDN, so we want to mimic the framework that supports SDN concepts. We can adjust the NS2 or use a particular SDN simulator like Mininet (with OpenFlow) for more precise SDN-based simulations. but, we can mimic a simplified version of SDN behaviour in NS2 by controlling network flows physically and mimic the role of an SDN controller.

  1. Define a Simplified SDN Topology in NS2

Generate a basic SDN-like topology in which we want to mimic SDN behaviour by controlling flows using a centralized controller (nController).

Example:

set ns [new Simulator]

set tracefile [open sdn_forensics.tr w]

$ns trace-all $tracefile

# Create nodes

set nController [$ns node]  ;# SDN Controller node

set n1 [$ns node]           ;# Host 1 (Sender)

set n2 [$ns node]           ;# Host 2 (Receiver)

set nSwitch [$ns node]       ;# SDN-enabled Switch

set nAttacker [$ns node]     ;# Malicious node (Attacker)

# Create links between the nodes

$ns duplex-link $n1 $nSwitch 1Mb 10ms DropTail

$ns duplex-link $n2 $nSwitch 1Mb 10ms DropTail

$ns duplex-link $nAttacker $nSwitch 1Mb 10ms DropTail

$ns duplex-link $nController $nSwitch 1Mb 10ms DropTail

  1. Simulate Traffic Flow Control Using the SDN Controller

In SDN, the controller orders how packets are transmitted by installing flow rules in the switch. We can mimic this by controlling packet routing and forwarding via the controller node (nController).

(A) Set Up Normal Traffic

Configure normal traffic from n1 to n2. The SDN controller will control the flow of traffic by defining the path packets should take over the switch.

# Set up UDP traffic between n1 and n2

set udp1 [new Agent/UDP]

set null1 [new Agent/Null]

$ns attach-agent $n1 $udp1

$ns attach-agent $n2 $null1

$ns connect $udp1 $null1

# Create a CBR (Constant Bit Rate) traffic generator attached to UDP

set cbr1 [new Application/Traffic/CBR]

$cbr1 set packetSize_ 512

$cbr1 set rate_ 1Mb

$cbr1 attach-agent $udp1

# Define initial flow rules for the switch (as if controlled by the SDN controller)

proc install_flow {controller switch source dest} {

puts “$controller installing flow from $source to $dest through $switch”

# In a real SDN environment, flow table rules would be installed here.

}

# Start normal traffic and install flow rules

$ns at 1.0 “$cbr1 start”

$ns at 1.0 “install_flow nController nSwitch n1 n2”

  1. Simulate Malicious Activity (Attack Scenarios)

Next, mimic the attacks like packet injection or DDoS from the malicious node (nAttacker), and observe on how the SDN controller or forensic node reacts to these events.

(A) Packet Injection Attack

Mimic packet injection from the attacker node, in which the attacker attempts to insert unauthorized traffic into the network.

# Set up packet injection from the attacker node

set udpAttacker [new Agent/UDP]

set cbrAttacker [new Application/Traffic/CBR]

$cbrAttacker set packetSize_ 512

$cbrAttacker set rate_ 5Mb  ;# High rate to simulate attack

$cbrAttacker attach-agent $udpAttacker

# Connect attacker to the switch

$ns attach-agent $nAttacker $udpAttacker

$ns connect $udpAttacker $null1

# Start the attack at 2.0 seconds

$ns at 2.0 “$cbrAttacker start”

  1. Forensic Monitoring in SDN

To execute the forensics in SDN, we want to observe both control plane and data plane events. Control plane events can contain flow modifications, since data plane events contain traffic monitoring at the switch or hosts.

(A) Log Control Plane Events (Flow Rules)

In SDN, the controller often updates flow tables in the switches. Log these flow variations for forensic analysis.

# Function to log SDN flow rule changes

proc log_flow_change {controller switch flow_id src dest time} {

puts “SDN Forensics: Flow $flow_id installed by $controller at $time from $src to $dest through $switch”

}

# Simulate flow change logging

$ns at 1.5 “log_flow_change nController nSwitch 1 n1 n2 1.5”

$ns at 2.0 “log_flow_change nController nSwitch 2 nAttacker n2 2.0”

(B) Monitor Data Plane Events (Traffic Logs)

Monitor traffic at the switch and log abnormal events like unexpected traffic from unauthorized sources.

# Function to monitor traffic at the switch (data plane monitoring)

proc monitor_traffic {packet_id source dest size time} {

puts “Monitoring traffic: Packet $packet_id from $source to $dest, Size=$size, Time=$time”

if { $source == “nAttacker” } {

puts “Alert: Unauthorized traffic from $source detected!”

}

}

# Log traffic at the switch for forensic purposes

$ns at 1.5 “monitor_traffic 1 n1 n2 512 1.5”

$ns at 2.5 “monitor_traffic 2 nAttacker n2 512 2.5”

  1. Simulate SDN Forensics Investigation

Forensic investigation in SDN has contained to evaluate control plane and data plane logs, reconstructing attack events, and identifying policy violations or unusual behaviour.

(A) Reconstruct Events from Logs

After logging flow changes and traffic, rebuild events for forensic analysis. This could contain to classifying unauthorized traffic or flow rule violations.

# Function to reconstruct SDN forensic events from logs

proc reconstruct_forensic_events {flow_file traffic_file} {

puts “Reconstructing SDN forensic events…”

set flow_log [open $flow_file r]

set traffic_log [open $traffic_file r]

while {[gets $flow_log flow_line] >= 0} {

if {[regexp “Attacker” $flow_line]} {

puts “Suspicious flow detected: $flow_line”

}

}

while {[gets $traffic_log traffic_line] >= 0} {

if {[regexp “Unauthorized” $traffic_line]} {

puts “Suspicious traffic detected: $traffic_line”

}

}

close $flow_log

close $traffic_log

}

# Reconstruct forensic events after the simulation

$ns at 5.0 “reconstruct_forensic_events sdn_flow_log.txt sdn_traffic_log.txt”

  1. Detect and Respond to Forensic Alerts

When an anomaly is identified, the SDN controller or forensic system can take actions like blocking the malicious node, updating flow rules, or rerouting traffic.

(A) Take Corrective Action

If unauthorized traffic is identified, the SDN controller installs new flow rules to block the attacker.

# Function to block malicious traffic by updating flow rules

proc block_malicious_traffic {controller switch attacker} {

puts “$controller blocking traffic from $attacker at $switch”

# Install new flow rule to block the attacker

}

# Simulate blocking the attacker when unauthorized traffic is detected

$ns at 3.0 “block_malicious_traffic nController nSwitch nAttacker”

  1. Run the Simulation

Once script is ready, execute the simulation using NS2:

ns your_script.tcl

  1. Analyse Results

After the simulation done, measure the logs to see if the SDN controller appropriately managed traffic and detected the attack. Key aspects to focus on include:

  • Flow rules installation: How did the controller respond to the attack?
  • Traffic anomalies: Did the system identify unauthorized traffic?
  • Event correlation: How were control plane and data plane events connected for forensic analysis?

We can also use NAM (Network Animator) to envision network events that has how the traffic flows were handled.

  1. Extend the Simulation

We can expand this implementation by:

  • Adding more attack types: To mimic additional attacks, like DDoS, MITM, or flow table poisoning.
  • Advanced forensics techniques: Incorporate machine learning models to identify anomalous traffic patterns or policy violations.
  • Multi-layer forensics: Execute multi-layer forensics that tracks both the control plane and data plane more closely, tracing complex communication.
  • Controller behavior: Discover on how different SDN controllers such as OpenFlow handles security and forensics.

In this simulation, we clearly explained how to replicate and simulate the SDN forensics in ns2 tool that helps you to enhance the network flow and identify the unnecessary threats over the network. If you need more information regarding the SDN forensics we will provide it.

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