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How to Implement Network Forensics in ns3

To implement network forensics in ns-3, we create an application which capture and analyze network traffic for detecting and investigating security aspects. Let’s have a quick and elaborate guide on setting up a basic network, capturing packets, and implementing a simple network forensics application.

Steps for implementation

  1. Install ns-3

Make sure that ns-3 is installed in the computer. If not, install it from the official ns-3 website.

  1. Define the Network Topology

Define the network topology that contains:

  • Normal nodes (legitimate users)
  • Attacker nodes
  • Server nodes
  • Forensics nodes (nodes used to capture and analyze traffic)

 

  1. Create Network Nodes

Using NodeContainer, create network nodes.

NodeContainer normalNodes, attackerNodes, serverNodes, forensicNodes;

normalNodes.Create(3);

attackerNodes.Create(1);

serverNodes.Create(1);

forensicNodes.Create(1);

 

 

 

  1. Set Up Network Devices

Use the appropriate network interfaces to install network devices like Wi-Fi for wireless communication.

WifiHelper wifi;

wifi.SetStandard(WIFI_PHY_STANDARD_80211n_5GHZ);

WifiMacHelper mac;

mac.SetType(“ns3::AdhocWifiMac”);

YansWifiPhyHelper phy = YansWifiPhyHelper::Default();

YansWifiChannelHelper channel = YansWifiChannelHelper::Default();

phy.SetChannel(channel.Create());

NetDeviceContainer normalDevices = wifi.Install(phy, mac, normalNodes);

NetDeviceContainer attackerDevices = wifi.Install(phy, mac, attackerNodes);

NetDeviceContainer serverDevices = wifi.Install(phy, mac, serverNodes);

NetDeviceContainer forensicDevices = wifi.Install(phy, mac, forensicNodes);

  1. Configure Mobility Model

Set up the mobility model for the nodes using using MobilityHelper.

MobilityHelper mobility;

mobility.SetMobilityModel(“ns3::ConstantPositionMobilityModel”);

mobility.Install(normalNodes);

mobility.Install(attackerNodes);

mobility.Install(serverNodes);

mobility.Install(forensicNodes);

 

  1. Set Up Packet Capture

Capture packet traces using pcapHelper tracing for analysis. Configure packet capture on the forensic nodes.

PcapHelper pcapHelper;

Ptr<PcapFileWrapper> file = pcapHelper.CreateFile(“forensics.pcap”, std::ios::out, PcapHelper::DLT_PPP);

for (uint32_t i = 0; i < forensicDevices.GetN(); ++i) {

    phy.EnablePcap(“forensics_capture”, forensicDevices.Get(i), true, true);

}

  1. Implement Forensic Analysis Application

To analyzes captured packets for forensic purposes, Create an application. Here is an example of a packet sniffing application which logs packet details :

class ForensicApplication : public Application {

public:

    void StartApplication() override {

        recvSocket = Socket::CreateSocket(GetNode(), UdpSocketFactory::GetTypeId());

        recvSocket->Bind(InetSocketAddress(Ipv4Address::GetAny(), listenPort));

        recvSocket->SetRecvCallback(MakeCallback(&ForensicApplication::HandleRead, this));

    }

    void SetListenPort(uint16_t port) {

        listenPort = port;

    }

    void HandleRead(Ptr<Socket> socket) {

        Ptr<Packet> packet;

        Address from;

        while ((packet = socket->RecvFrom(from))) {

            LogPacket(packet, from);

        }

    }

    void LogPacket(Ptr<Packet> packet, Address from) {

        std::cout << “Captured packet from ” << InetSocketAddress::ConvertFrom(from).GetIpv4()

                  << ” of size ” << packet->GetSize() << std::endl;

    }

private:

    Ptr<Socket> recvSocket;

    uint16_t listenPort;

};

  1. Set Up Applications

Install the applications on the nodes.

ApplicationContainer normalApps, attackerApps, serverApps, forensicApps;

// Normal node applications (e.g., sending normal traffic)

for (uint32_t i = 0; i < normalNodes.GetN(); ++i) {

    OnOffHelper onoff(“ns3::UdpSocketFactory”, InetSocketAddress(serverNodes.Get(0)->GetObject<Ipv4>()->GetAddress(1, 0).GetLocal(), 9));

    onoff.SetConstantRate(DataRate(“500kb/s”));

    ApplicationContainer app = onoff.Install(normalNodes.Get(i));

    app.Start(Seconds(1.0));

    app.Stop(Seconds(20.0));

    normalApps.Add(app);

}

// Attacker node applications (e.g., DoS attack)

for (uint32_t i = 0; i < attackerNodes.GetN(); ++i) {

    OnOffHelper onoff(“ns3::UdpSocketFactory”, InetSocketAddress(serverNodes.Get(0)->GetObject<Ipv4>()->GetAddress(1, 0).GetLocal(), 9));

    onoff.SetConstantRate(DataRate(“10Mb/s”));

    ApplicationContainer app = onoff.Install(attackerNodes.Get(i));

    app.Start(Seconds(5.0));

    app.Stop(Seconds(20.0));

    attackerApps.Add(app);

}

// Server node application (e.g., packet sink)

PacketSinkHelper sink(“ns3::UdpSocketFactory”, InetSocketAddress(Ipv4Address::GetAny(), 9));

serverApps.Add(sink.Install(serverNodes.Get(0)));

// Forensic node application

Ptr<ForensicApplication> forensicApp = CreateObject<ForensicApplication>();

forensicApp->SetListenPort(9);

forensicNodes.Get(0)->AddApplication(forensicApp);

forensicApp->SetStartTime(Seconds(1.0));

forensicApp->SetStopTime(Seconds(20.0));

forensicApps.Add(forensicApp);

serverApps.Start(Seconds(1.0));

serverApps.Stop(Seconds(20.0));

  1. Set Up Routing Protocols

Configure routing protocols for the network.

AodvHelper aodv;

InternetStackHelper internet;

internet.SetRoutingHelper(aodv);

internet.Install(normalNodes);

internet.Install(attackerNodes);

internet.Install(serverNodes);

internet.Install(forensicNodes);

  1. Assign IP Addresses

Using Ipv4AddressHelper address, assign IP addresses to the network devices.

Ipv4AddressHelper address;

address.SetBase(“10.1.1.0”, “255.255.255.0”);

Ipv4InterfaceContainer normalInterfaces = address.Assign(normalDevices);

Ipv4InterfaceContainer attackerInterfaces = address.Assign(attackerDevices);

Ipv4InterfaceContainer serverInterfaces = address.Assign(serverDevices);

Ipv4InterfaceContainer forensicInterfaces = address.Assign(forensicDevices);

  1. 11. Run the Simulation

Define the simulation runtime and execute it.

Simulator::Stop(Seconds(20.0));

Simulator::Run();

Simulator::Destroy();

Example of a Simple Network Forensics Script :

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “ns3/wifi-module.h”

#include “ns3/mobility-module.h”

#include “ns3/applications-module.h”

#include “ns3/aodv-module.h”

using namespace ns3;

class ForensicApplication : public Application {

public:

    void StartApplication() override {

        recvSocket = Socket::CreateSocket(GetNode(), UdpSocketFactory::GetTypeId());

        recvSocket->Bind(InetSocketAddress(Ipv4Address::GetAny(), listenPort));

        recvSocket->SetRecvCallback(MakeCallback(&ForensicApplication::HandleRead, this));

    }

    void SetListenPort(uint16_t port) {

        listenPort = port;

    }

 

    void HandleRead(Ptr<Socket> socket) {

        Ptr<Packet> packet;

        Address from;

        while ((packet = socket->RecvFrom(from))) {

            LogPacket(packet, from);

        }

    }

    void LogPacket(Ptr<Packet> packet, Address from) {

        std::cout << “Captured packet from ” << InetSocketAddress::ConvertFrom(from).GetIpv4()

                  << ” of size ” << packet->GetSize() << std::endl;

    }

private:

    Ptr<Socket> recvSocket;

    uint16_t listenPort;

};

int main(int argc, char *argv[]) {

    NodeContainer normalNodes, attackerNodes, serverNodes, forensicNodes;

    normalNodes.Create(3);

    attackerNodes.Create(1);

    serverNodes.Create(1);

    forensicNodes.Create(1);

 

    // WiFi setup

    WifiHelper wifi;

    wifi.SetStandard(WIFI_PHY_STANDARD_80211n_5GHZ);

    WifiMacHelper mac;

    mac.SetType(“ns3::AdhocWifiMac”);

    YansWifiPhyHelper phy = YansWifiPhyHelper::Default();

    YansWifiChannelHelper channel = YansWifiChannelHelper::Default();

    phy.SetChannel(channel.Create());

    NetDeviceContainer normalDevices = wifi.Install(phy, mac, normalNodes);

    NetDeviceContainer attackerDevices = wifi.Install(phy, mac, attackerNodes);

    NetDeviceContainer serverDevices = wifi.Install(phy, mac, serverNodes);

    NetDeviceContainer forensicDevices = wifi.Install(phy, mac, forensicNodes);

    // Mobility setup

    MobilityHelper mobility;

    mobility.SetMobilityModel(“ns3::ConstantPositionMobilityModel”);

    mobility.Install(normalNodes);

    mobility.Install(attackerNodes);

    mobility.Install(serverNodes);

    mobility.Install(forensicNodes);

    // Internet stack and routing

    AodvHelper aodv;

    InternetStackHelper internet;

    internet.SetRoutingHelper(aodv);

    internet.Install(normalNodes);

    internet.Install(attackerNodes);

    internet.Install(serverNodes);

    internet.Install(forensicNodes);

    Ipv4AddressHelper address;

    address.SetBase(“10.1.1.0”, “255.255.255.0”);

    Ipv4InterfaceContainer normalInterfaces = address.Assign(normalDevices);

    Ipv4InterfaceContainer attackerInterfaces = address.Assign(attackerDevices);

    Ipv4InterfaceContainer serverInterfaces = address.Assign(serverDevices);

    Ipv4InterfaceContainer forensicInterfaces = address.Assign(forensicDevices);

    // Set up packet capture

    PcapHelper pcapHelper;

    Ptr<PcapFileWrapper> file = pcapHelper.CreateFile(“forensics.pcap”, std::ios::out, PcapHelper::DLT_PPP);

    for (uint32_t i = 0; i < forensicDevices.GetN(); ++i) {

        phy.EnablePcap(“forensics_capture”, forensicDevices.Get(i), true, true);

    }

    // Install applications

    ApplicationContainer normalApps, attackerApps, serverApps, forensicApps;

    // Normal node applications (e.g., sending normal traffic)

    for (uint32_t i = 0; i < normalNodes.GetN(); ++i) {

        OnOffHelper onoff(“ns3::UdpSocketFactory”, InetSocketAddress(serverNodes.Get(0)->GetObject<Ipv4>()->GetAddress(1, 0).GetLocal(), 9));

        onoff.SetConstantRate(DataRate(“500kb/s”));

        ApplicationContainer app = onoff.Install(normalNodes.Get(i));

        app.Start(Seconds(1.0));

        app.Stop(Seconds(20.0));

        normalApps.Add(app);

    }

    // Attacker node applications (e.g., DoS attack)

    for (uint32_t i = 0; i < attackerNodes.GetN(); ++i) {

        OnOffHelper onoff(“ns3::UdpSocketFactory”, InetSocketAddress(serverNodes.Get(0)->GetObject<Ipv4>()->GetAddress(1, 0).GetLocal(), 9));

        onoff.SetConstantRate(DataRate(“10Mb/s”));

        ApplicationContainer app = onoff.Install(attackerNodes.Get(i));

        app.Start(Seconds(5.0));

        app.Stop(Seconds(20.0));

        attackerApps.Add(app);

    }

    // Server node application (e.g., packet sink)

    PacketSinkHelper sink(“ns3::UdpSocketFactory”, InetSocketAddress(Ipv4Address::GetAny(), 9));

    serverApps.Add(sink.Install(serverNodes.Get(0)));

    // Forensic node application

    Ptr<ForensicApplication> forensicApp = CreateObject<ForensicApplication>();

    forensicApp->SetListenPort(9);

    forensicNodes.Get(0)->AddApplication(forensicApp);

    forensicApp->SetStartTime(Seconds(1.0));

    forensicApp->SetStopTime(Seconds(20.0));

    forensicApps.Add(forensicApp);

    serverApps.Start(Seconds(1.0));

    serverApps.Stop(Seconds(20.0));

    Simulator::Stop(Seconds(20.0));

    Simulator::Run();

    Simulator::Destroy();

    return 0;

}

Overall, we had learned on implementing network forensics in ns-3 by creating an application that captures and analyzes network traffic to detect and investigate security incidents. Also we offer more programming support on network forensics.