To simulate the Fragmentation Attack is a network attack using NS2 environment that aims the packet fragmentation and reassembly process. In such an attack, the attacker transmits the influenced fragmented packets, which make use of vulnerabilities in the way the obtaining the system reassembles them. These fragmentation attacks can direct to security breaches, packet corruption, or denial of service (DoS).
In the network simulator NS2, we can replicate a fragmentation attack by designing how an attacker transmits the malformed or overlapping fragments to a target node. NS2 supports packet fragmentation at the link layer for large data transmissions, thus we can be replicated the method in which fragments are transmitted and reassembled incorrectly by reason of the attack.
Steps to Simulate Fragmentation Attack in NS2
Step 1: Set Up NS2
Make sure NS2 is installed on the machine. The fragmentation attack will be replicated by utilizing the UDP packets that can be fragmented, if they surpass the Maximum Transmission Unit (MTU) size on the network.
Step 2: Understand the Fragmentation Attack
In a fragmentation attack, the attacker transmits the fragmented packets, including a few fragments either:
- Overlapping: triggering the ambiguity in packet reassembly that probably leading to buffer overflows or security breaches.
- Missing: exit unfinished fragments, which the target may manage imperfectly.
- Malformed: transmitting the invalid fragment headers that trigger the target to crash or perform unpredictably.
Step 3: Design the Network Topology
We will create a basic network topology with:
- Client Node: Makes legitimate traffic, which is fragmented by reason of the large packet size.
- Attacker Node: Transmits the fragmented packets with manipulated fragment headers to utilize the reassembly vulnerabilities.
- Target Node: From both the client and attacker we can obtain the fragments.
Step 4: Create an NS2 TCL Script for Simulating Fragmentation Attack
The following is an NS2 TCL script, which mimics a fragmentation attack in which an attacker transmits the malformed fragments to the target.
Example: Fragmentation Attack Simulation in NS2
# Create a new NS2 simulator object
set ns [new Simulator]
# Define network topology with 3 nodes
set client [$ns node] ;# Legitimate Client sending fragmented packets
set attacker [$ns node] ;# Attacker sending malformed fragmented packets
set target [$ns node] ;# Target server receiving fragmented packets
# Create duplex links between the nodes (with 1Mb bandwidth, 10ms delay)
$ns duplex-link $client $target 1Mb 10ms DropTail
$ns duplex-link $attacker $target 1Mb 10ms DropTail
# Enable queue tracing between client, attacker, and target
$ns trace-queue $client $target “tracefile.tr”
$ns trace-queue $attacker $target “tracefile.tr”
# Define UDP agents for client and attacker
set udp_client [new Agent/UDP]
$ns attach-agent $client $udp_client
set udp_attacker [new Agent/UDP]
$ns attach-agent $attacker $udp_attacker
# Define a UDP sink (Null agent) at the target to receive packets
set sink [new Agent/Null]
$ns attach-agent $target $sink
# Connect client and attacker to the target
$ns connect $udp_client $sink
$ns connect $udp_attacker $sink
# Define large packet size for legitimate traffic to trigger fragmentation
set cbr_client [new Application/Traffic/CBR]
$cbr_client set packetSize_ 2048 ;# Large packet size triggers fragmentation
$cbr_client set interval_ 0.1 ;# 10 packets per second
$cbr_client attach-agent $udp_client
# Start legitimate client traffic at 1.0 seconds
$ns at 1.0 “$cbr_client start”
puts “Client starts sending fragmented packets at 1.0 seconds.”
# Define malformed fragmented traffic from the attacker
proc send_malformed_fragments {attacker} {
global ns udp_attacker
puts “Attacker sends malformed fragments at 2.0 seconds.”
# Simulating the fragmentation attack
# Using a large packet size and manipulating the fragmentation headers conceptually
set cbr_attack [new Application/Traffic/CBR]
$cbr_attack set packetSize_ 2048 ;# Large packet size to trigger fragmentation
$cbr_attack set interval_ 0.01 ;# High rate to simulate flooding with fragments
$cbr_attack attach-agent $udp_attacker
# Sending the attack packets
$ns at 2.0 “$cbr_attack start”
}
# Schedule the attacker to send malformed fragments at 2.0 seconds
$ns at 2.0 “send_malformed_fragments $attacker”
# Stop all traffic after 10 seconds
$ns at 10.0 “$cbr_client stop”
$ns at 10.0 “$udp_attacker reset”
# Trace file for recording the simulation events
set tracefile [open “fragmentation_attack.tr” w]
$ns trace-all $tracefile
# NAM file for network animation
set namfile [open “fragmentation_attack.nam” w]
$ns namtrace-all $namfile
# Define the finish procedure
proc finish {} {
global ns tracefile namfile
$ns flush-trace
close $tracefile
close $namfile
exec nam fragmentation_attack.nam &
exit 0
}
# Finish the simulation after 12 seconds
$ns at 12.0 “finish”
# Run the simulation
$ns run
Step 5: Explanation of the Script
- Network Setup:
- The network has three nodes they are a client transmitting the legitimate traffic, an attacker sending malformed fragmented traffic, and then a target getting the fragmented packets.
- Duplex links are associate the client and attacker to the target including a bandwidth of 1Mb and a delay of 10ms.
- Legitimate Fragmented Traffic:
- The client transmits UDP packets utilizing the CBR (Constant Bit Rate) with a packet size of 2048 bytes that surpasses the normal MTU size that forcing fragmentation.
- The CBR traffic is transmitted at an interval of 0.1 seconds (10 packets for each second).
- Attacker’s Fragmentation Attack:
- The attacker utilizes CBR traffic including a large packet size (2048 bytes) to push the fragmentation, however the behavior is changed to replicate a fragmentation attack by transmitting the fragmented packets at a much higher rate.
- It is theoretically a way to replicate the attacker transmitting the malformed fragments, which could utilize vulnerabilities in how the target node rebuilds the packets.
- The attack begins at 2.0 seconds that flooding the target with overlapping or unfinished fragments.
- Tracing and Visualization:
- A trace file (fragmentation_attack.tr) is made to record the simulation events.
- A NAM file (fragmentation_attack.nam) is generated to envision the attack using NAM.
Step 6: Run the Simulation
- We can save the script as fragmentation_attack.tcl.
- Execute the script in NS2:
ns fragmentation_attack.tcl
It will generate two files:
- fragmentation_attack.tr: A trace files logging the packet-level information.
- fragmentation_attack.nam: A NAM file for envisioning the attack in NAM.
Step 7: Visualize the Simulation Using NAM
To envision the fragmentation attack in NAM:
nam fragmentation_attack.nam
In NAM, we will see:
- The client transmitting the fragmented packets to the target.
- The attacker overflowing the target with high-rate that malformed fragmented packets after 2.0 seconds, which replicating a fragmentation attack.
Step 8: Analyze the Trace File
The trace file (fragmentation_attack.tr) includes in-depth information regarding the packet transmissions, including:
- Fragmented packets from both the legitimate client and the attacker.
- The impacts of the high-rate attack on the network and target node.
We can investigate the trace file utilizing AWK, Python, or custom scripts to:
- Assess the packet delivery ratio.
- Monitor packet reassembly issues or packet drops because of the fragmentation attacks.
- Observe network congestion triggered by the attack.
Step 9: Enhance the Simulation
The following is a few ways to expand or improve the simulation:
- Add More Complex Attacks: Execute more precise fragmentation attacks, like transmitting the overlapping fragments or fragments including incorrect offsets.
- Introduce Defense Mechanisms: Insert mechanisms at the target node to identify and mitigate malformed fragments, like Intrusion Detection Systems (IDS).
- Simulate Different Traffic Types: Test with other protocols (e.g., ICMP or TCP) and replicate the fragmentation attacks are aiming these protocols.
- Increase the Attack Intensity: Include additional attackers or maximize the rate of malformed fragments to devastate the target node.
- Measure Impact: Examine the influence of the attack on network performance that containing the performance parameters like throughput, latency, and packet loss.
We had thoroughly shown the entire structured details and simulation approach on how to replicate and analyse the Fragmentation Attack projects using NS2. We are furnished to deliver essential insights relevant to this subject, if required. We invite you to share the details of your projects focused on simulating fragmentation attack scenarios using NS2. Connect with us at phdprime.com, where our team of experts is dedicated to offering personalized support to scholars like you.
