How to Develop Simple Mail Transfer Protocol Projects Using NS3

To develop the Simple Mail Transfer Protocol (SMTP) project using NS3 include for replicate an email transfer network using NS3’s networking components. Here’s a step-by-step guide:

Steps to Develop Simple Mail Transfer Protocol Projects Using NS3

1. Understand SMTP in NS3 Context

SMTP used for email transfer in application layer protocol. NS3 does not natively encourage for SMTP, nevertheless we can replicate it using:

• TCP connections (SMTP is TCP-based on protocol, usually over port 25)
• Packet-level replication to design the SMTP behavior
• Application layer traffic generation for replicate the email data transmission

2. Setup NS3 Environment

Make sure we have NS3 installed. If not, install it using:

git clone

cd ns-3-dev

./build.py –enable-examples

3. Create an SMTP Traffic Model

We replicate for SMTP traffic, we can built the simple application layer model which forwarding the emails among the sender (SMTP client) and mail server.

SMTP Traffic Behavior in NS3

1. Transmitter for initiates the TCP link to SMTP server (port 25)
2. Sender forward the email communication
3. Server acknowledges and relays communication
4. Receiver retrieves communication from the server
5. Implement the Simulation Code

Here is simple for NS3 C++ script to replicate a SMTP:

smtp-simulation.cc

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “ns3/applications-module.h”

#include “ns3/point-to-point-module.h”

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“SMTP_Simulation”);

class SmtpClient : public Application {

private:

Ptr<Socket> m_socket;

Address m_serverAddress;

uint16_t m_port;

EventId m_event;

bool m_running;

public:

SmtpClient() : m_socket(0), m_port(25), m_running(false) {}

void Setup(Address serverAddress) {

m_serverAddress = serverAddress;

}

void StartApplication() {

m_socket = Socket::CreateSocket(GetNode(), TcpSocketFactory::GetTypeId());

m_socket->Connect(m_serverAddress);

SendEmail();

}

void SendEmail() {

std::string message = “SMTP MESSAGE: HELLO SERVER\n”;

Ptr<Packet> packet = Create<Packet>((uint8_t*)message.c_str(), message.length());

m_socket->Send(packet);

}

};

class SmtpServer : public Application {

private:

Ptr<Socket> m_socket;

public:

SmtpServer() : m_socket(0) {}

void StartApplication() {

m_socket = Socket::CreateSocket(GetNode(), TcpSocketFactory::GetTypeId());

InetSocketAddress local = InetSocketAddress(Ipv4Address::GetAny(), 25);

m_socket->Bind(local);

m_socket->Listen();

m_socket->SetRecvCallback(MakeCallback(&SmtpServer::HandleRead, this));

}

void HandleRead(Ptr<Socket> socket) {

Ptr<Packet> packet = socket->Recv();

std::cout << “SMTP SERVER RECEIVED: ” << packet->GetSize() << ” Bytes” << std::endl;

}

};

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

NodeContainer nodes;

nodes.Create(2);

PointToPointHelper p2p;

p2p.SetDeviceAttribute(“DataRate”, StringValue(“1Mbps”));

p2p.SetChannelAttribute(“Delay”, StringValue(“2ms”));

NetDeviceContainer devices = p2p.Install(nodes);

InternetStackHelper stack;

stack.Install(nodes);

Ipv4AddressHelper address;

address.SetBase(“192.168.1.0”, “255.255.255.0”);

Ipv4InterfaceContainer interfaces = address.Assign(devices);

Ptr<SmtpServer> serverApp = CreateObject<SmtpServer>();

serverApp->SetStartTime(Seconds(1.0));

serverApp->SetStopTime(Seconds(10.0));

nodes.Get(1)->AddApplication(serverApp);

Ptr<SmtpClient> clientApp = CreateObject<SmtpClient>();

clientApp->Setup(InetSocketAddress(interfaces.GetAddress(1), 25));

clientApp->SetStartTime(Seconds(2.0));

clientApp->SetStopTime(Seconds(10.0));

nodes.Get(0)->AddApplication(clientApp);

Simulator::Run();

Simulator::Destroy();

return 0;

}

5. Compile and Run
6. Locate the file inside NS3’s for scratch directory:

mv smtp-simulation.cc ns-3-dev/scratch/

2. Compile the code:

./waf –run scratch/smtp-simulation

6. Explanation of the Code

• Nodes: 2 nodes (Client & Server)
• Point-to-Point Link: 1 Mbps, 2 ms delay
• SmtpClient Class: Generate a TCP connection and forwarding the replicated SMTP email
• SmtpServer Class: Receives the SMTP communication and designs their size
• Simulation Duration: 10 seconds gives the replication duration

7. Enhancements

• Implement SMTP Commands: Encompass to assist the commands such as HELO, MAIL FROM, RCPT TO, DATA, QUIT
• Simulate Email Storage: Secure the received communication in queue
• Add Latency and Delay Effects: It used the NS3’s network impacts
• Simulate Multiple Clients: Build a further SMTP clients and scale traffic

At the end, we thorough the manual and deliver the valuable insights regarding how to simulate the Simple Mail Transfer Protocol in ns3 tool. Further details regarding the implementation of the Simple Mail Transfer Protocol in diverse simulations will be provided.