How to Begin Implement IMAP POP3 Email Protocol in NS3

To start implementing Internet Message Access Protocol (IMAP) and Post Office Protocol (POP3) using NS3, we’ll need to replicate the email interaction behavior that addressing the recovery messages from a mail server to a client. These protocols are function on the Application Layer and it will utilize TCP for reliable interaction like a transport protocol.

Here, we can follow series of steps for executing IMAP and POP3 in NS3:

Steps to Begin Implement IMAP POP3 Email Protocol in NS3

Step 1: Understand IMAP and POP3

1. IMAP:
   • It is utilized for recovering email messages from a server.
   • Permits emails synchronization through several devices.
   • Emails are saved on the server including operations such as analysis and removing are remotely completed.
2. POP3:
   • Designed for recover emails from a server.
   • Emails are downloaded to the client who frequently removing them from the server.
3. Simplifications for Simulation:
   • Below is a crucial procedures to replicate:
     • Connection establishment through TCP.
     • Recovery of email messages.
     • Simple commands such as LIST, RETR, and DELE for POP3 or SELECT, FETCH for IMAP.

Step 2: Set Up Your NS3 Environment

1. Create a Directory:
   • Make a directory for execution in src/applications/ such as src/email/.
2. Add Necessary Files:
   • imap-pop3-server-application.h: It is a server-side application header.
   • imap-pop3-client-application.cc: Client-side application implementation.
   • imap-pop3-server-application.cc: Server-side application execution.
   • imap-pop3-client-application.h: Client-side application header.
3. Update Build System:
   • Adjust wscript with the new module for updating system.

Step 3: Design the Applications

1. Server Application

The server pays attention to receiving TCP connections, processes client commands, and transmits proper replies.

Header File (imap-pop3-server-application.h)

#include “ns3/application.h”

#include “ns3/socket.h”

class EmailServerApplication : public ns3::Application {

public:

static ns3::TypeId GetTypeId (void);

EmailServerApplication ();

virtual ~EmailServerApplication ();

void Setup (uint16_t port);

protected:

virtual void StartApplication (void);

virtual void StopApplication (void);

private:

void HandleConnection (ns3::Ptr<ns3::Socket> socket);

void HandleRead (ns3::Ptr<ns3::Socket> socket);

ns3::Ptr<ns3::Socket> m_socket;

uint16_t m_port;

std::map<std::string, std::string> m_mailbox; // Simple mailbox storage

};

Implementation File (imap-pop3-server-application.cc)

#include “imap-pop3-server-application.h”

#include “ns3/log.h”

NS_LOG_COMPONENT_DEFINE (“EmailServerApplication”);

NS_OBJECT_ENSURE_REGISTERED (EmailServerApplication);

ns3::TypeId EmailServerApplication::GetTypeId (void) {

static ns3::TypeId tid = ns3::TypeId (“ns3::EmailServerApplication”)

.SetParent<ns3::Application> ()

.SetGroupName (“Applications”)

.AddConstructor<EmailServerApplication> ();

return tid;

}

EmailServerApplication::EmailServerApplication () : m_socket (0), m_port (0) {}

EmailServerApplication::~EmailServerApplication () {

m_socket = nullptr;

}

void EmailServerApplication::Setup (uint16_t port) {

m_port = port;

m_mailbox[“test@example.com”] = “Welcome to IMAP/POP3 Simulation!”;

}

void EmailServerApplication::StartApplication () {

NS_LOG_INFO (“Starting Email Server on port ” << m_port);

m_socket = ns3::Socket::CreateSocket (GetNode (), ns3::TcpSocketFactory::GetTypeId ());

ns3::InetSocketAddress localAddress = ns3::InetSocketAddress (ns3::Ipv4Address::GetAny (), m_port);

m_socket->Bind (localAddress);

m_socket->Listen ();

m_socket->SetAcceptCallback (

ns3::MakeCallback (&EmailServerApplication::HandleConnection, this),

ns3::MakeNullCallback<void, ns3::Ptr<ns3::Socket>> ());

}

void EmailServerApplication::StopApplication () {

NS_LOG_INFO (“Stopping Email Server”);

if (m_socket) {

m_socket->Close ();

}

}

void EmailServerApplication::HandleConnection (ns3::Ptr<ns3::Socket> socket) {

NS_LOG_INFO (“Accepted connection”);

socket->SetRecvCallback (ns3::MakeCallback (&EmailServerApplication::HandleRead, this));

}

void EmailServerApplication::HandleRead (ns3::Ptr<ns3::Socket> socket) {

ns3::Ptr<ns3::Packet> packet = socket->Recv ();

std::string command;

packet->CopyData ((uint8_t *)command.c_str (), packet->GetSize ());

NS_LOG_INFO (“Received command: ” << command);

if (command == “LIST”) {

std::string response = “Messages:\n1. Welcome Message\n”;

socket->Send (ns3::Create<ns3::Packet> ((uint8_t *)response.c_str (), response.size ()));

} else if (command == “RETR”) {

std::string response = m_mailbox[“test@example.com”];

socket->Send (ns3::Create<ns3::Packet> ((uint8_t *)response.c_str (), response.size ()));

} else {

std::string response = “Unknown command.\n”;

socket->Send (ns3::Create<ns3::Packet> ((uint8_t *)response.c_str (), response.size ()));

}

}

2. Client Application

The client launches a TCP link to the server, forwards commands, and executes replies.

Header File (imap-pop3-client-application.h)

#include “ns3/application.h”

#include “ns3/socket.h”

class EmailClientApplication : public ns3::Application {

public:

static ns3::TypeId GetTypeId (void);

EmailClientApplication ();

virtual ~EmailClientApplication ();

void Setup (ns3::Ptr<ns3::Socket> socket, ns3::Address address);

protected:

virtual void StartApplication (void);

virtual void StopApplication (void);

private:

void SendCommand ();

void HandleResponse (ns3::Ptr<ns3::Socket> socket);

ns3::Ptr<ns3::Socket> m_socket;

ns3::Address m_serverAddress;

};

Implementation File (imap-pop3-client-application.cc)

Execute the client-side logic for transmitting commands like LIST, RETR, and so on and handle the replies.

Step 4: Write a Simulation Script

Experiment the applications within a basic simulation configuration.

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “imap-pop3-server-application.h”

#include “imap-pop3-client-application.h”

using namespace ns3;

int main () {

NodeContainer nodes;

nodes.Create (2);

InternetStackHelper stack;

stack.Install (nodes);

PointToPointHelper p2p;

p2p.SetDeviceAttribute (“DataRate”, StringValue (“10Mbps”));

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

NetDeviceContainer devices = p2p.Install (nodes);

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer interfaces = address.Assign (devices);

// Server setup

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

serverApp->Setup (8080);

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

serverApp->SetStartTime (Seconds (1.0));

serverApp->SetStopTime (Seconds (10.0));

// Client setup

Ptr<Socket> clientSocket = Socket::CreateSocket (nodes.Get (0), TcpSocketFactory::GetTypeId ());

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

clientApp->Setup (clientSocket, InetSocketAddress (interfaces.GetAddress (1), 8080));

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

clientApp->SetStartTime (Seconds (2.0));

clientApp->SetStopTime (Seconds (10.0));

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Step 5: Build and Test

1. Compile:

./waf configure

./waf build

1. Run Simulation:

./waf –run your-script

Step 6: Extend and Validate

1. Validation:
   • Confirm packet swaps to leverage the NS3 tracing as AsciiTraceHelper, PcapHelper.
   • Replicate diverse scenarios like delays or packet loss.
2. Extensions:
   • Integrate the IMAP-specific commands such as SELECT and FETCH.
   • For secure email interaction, we need to execute SSL/TLS encryption.

Through this guide, we had comprehensively delivered the implementation steps in sequence which is essential for IMAP POP3 Email Protocol utilising NS3 environment. Furthermore, we will be presented more information about this topic in another manual.