To simulate a Simple Mail Transfer Protocol (SMTP) project in OMNeT++ has includes designing the communication among the mail clients (senders), mail servers, and possibly relays in a network. SMTP is a standard protocol utilized for sending emails via the internet, and the simulation can illustrate how messages are routed, queued, and delivered.Share with us all your research needs we will help you with best simulation guidance.
Here’s a step-by-step guide on how to simulate SMTP in OMNeT++ using custom implementations, by way of SMTP is a higher-level application protocol, not directly available in INET.
We will design the features of SMTP components, like clients and servers, and replicate the sending of email messages across the network tailored to your projects, so get your work done by our developers.
Steps to Simulate Simple Mail Transfer Protocol Projects in OMNeT++
Step 1: Install OMNeT++ and INET Framework
Make sure that OMNeT++ and the INET framework are installed on the system, by way of the INET framework delivers essential networking modules such as hosts and routers.
- Download OMNeT++: OMNeT++
- Download INET Framework: INET Framework
Step 2: Define the Network Topology in the NED File
We will describe a simple network topology in a .ned file that contain mail clients, mail servers, and optionally relays.
Here’s an instance of a network in which an email client transmit an email to a mail server, that forwards it to another mail server, and the email is delivered to the recipient’s client.
network SMTPNetwork
{
submodules:
client1: StandardHost {
@display(“p=100,200”);
}
server1: StandardHost {
@display(“p=300,200”);
}
server2: StandardHost {
@display(“p=500,200”);
}
client2: StandardHost {
@display(“p=700,200”);
}
connections:
client1.ethg++ <–> Eth100M <–> server1.ethg++;
server1.ethg++ <–> Eth100M <–> server2.ethg++;
server2.ethg++ <–> Eth100M <–> client2.ethg++;
}
In this topology:
- client1 sends an email to client2.
- server1 and server2 are the mail servers managing SMTP transactions among clients.
Step 3: Implement SMTP in C++
We need to apply the logic for the SMTP protocol. SMTP utilize a request-response model, in which the client transmit email data to the server using commands such as HELO, MAIL FROM, RCPT TO, DATA, and QUIT.
Step 3.1: Create the SMTP Client Class
The SMTPClient will start the communication, transmit the email, and wait for responses from the server.
class SMTPClient : public cSimpleModule
{
protected:
virtual void initialize() override;
virtual void handleMessage(cMessage *msg) override;
void sendEmail();
void processServerResponse(cMessage *msg);
};
Define_Module(SMTPClient);
void SMTPClient::initialize()
{
// Simulate sending the email at the beginning of the simulation
if (strcmp(getName(), “client1”) == 0) {
sendEmail();
}
}
void SMTPClient::handleMessage(cMessage *msg)
{
// Process server response
processServerResponse(msg);
}
void SMTPClient::sendEmail()
{
// Simulate the sequence of SMTP commands
EV << “Sending email from client1 to server1\n”;
cMessage *email = new cMessage(“HELO”);
send(email, “ethg$o”);
}
void SMTPClient::processServerResponse(cMessage *msg)
{
if (strcmp(msg->getName(), “250 OK”) == 0) {
// Continue with next SMTP command, for example, MAIL FROM
cMessage *mailFrom = new cMessage(“MAIL FROM:<client1@example.com>”);
send(mailFrom, “ethg$o”);
}
delete msg;
}
Step 3.2: Create the SMTP Server Class
The SMTPServer will respond to the client, manage the incoming commands, and forward the email if essential.
class SMTPServer : public cSimpleModule
{
protected:
virtual void handleMessage(cMessage *msg) override;
void processClientRequest(cMessage *msg);
};
Define_Module(SMTPServer);
void SMTPServer::handleMessage(cMessage *msg)
{
processClientRequest(msg);
}
void SMTPServer::processClientRequest(cMessage *msg)
{
if (strcmp(msg->getName(), “HELO”) == 0) {
EV << “Server received HELO command\n”;
cMessage *response = new cMessage(“250 OK”);
send(response, “ethg$o”);
} else if (strstr(msg->getName(), “MAIL FROM”) != nullptr) {
EV << “Server received MAIL FROM command\n”;
cMessage *response = new cMessage(“250 OK”);
send(response, “ethg$o”);
}
// Handle other SMTP commands (RCPT TO, DATA, QUIT)
delete msg;
}
The server responds with “250 OK” to acknowledge commands from the client, and we can prolong it to manage other SMTP commands such as RCPT TO, DATA, and QUIT.
Step 4: Configure the Simulation in omnetpp.ini
In the omnetpp.ini file, set up the network settings, like the IP addresses for the clients and servers, and any link metrics such as data rate and delay.
[Config SMTPNetworkSimulation]
network = SMTPNetwork
sim-time-limit = 100s
# Assign IP addresses to the clients and servers
*.client1.ipv4.config = “manual”
*.client1.ipv4.addresses = “10.0.0.1/24”
*.server1.ipv4.config = “manual”
*.server1.ipv4.addresses = “10.0.0.254/24”
*.server2.ipv4.config = “manual”
*.server2.ipv4.addresses = “10.0.1.254/24”
*.client2.ipv4.config = “manual”
*.client2.ipv4.addresses = “10.0.1.1/24”
# Set up link parameters (e.g., delay, bandwidth)
*.client1.eth[0].datarate = 100Mbps
*.server1.eth[0].datarate = 100Mbps
*.server2.eth[0].datarate = 100Mbps
*.client2.eth[0].datarate = 100Mbps
This configuration making sure that client1 can send an email through server1 and server2, and that client2 can receive the email.
Step 5: Simulate the SMTP Transactions
Once the network is configured and the protocol logic is executed:
- Build and compile the project in OMNeT++.
- Run the simulation in the OMNeT++ GUI or from the command line.
- Observe SMTP transactions: The OMNeT++ GUI will envision the flow of SMTP commands (HELO, MAIL FROM, etc.) among the client and the servers.
We should see:
- client1 sending an email to server1 using the SMTP commands.
- server1 forwarding the email to server2 (if needed).
- client2 eventually receiving the email.
Step 6: Analyse Simulation Results
OMNeT++ creates .sca and .vec files encompassing the outcomes of the simulation like the time it took to transmit and deliver the email, the number of SMTP commands interchanged, and overall network performance.
We can measure key parameters, such as:
- Email delivery time: The total time taken for the email to travel from client1 to client2.
- Message throughput: How many emails are successfully delivered in a given time period.
- Network latency: The latency experienced at different stages of the SMTP communication.
Utilize OMNeT++’s built-in tools to plot and evaluate these outcome.
Step 7: Extend the SMTP Simulation
Once we have the simple SMTP protocol working, we can prolong the simulation with additional characteristics:
7.1: Support for Relays and Multiple Hops
We can establish intermediate mail relays that manage the email before it reaches the final destination.
network SMTPRelayNetwork
{
submodules:
client1: StandardHost;
relayServer: StandardHost;
server2: StandardHost;
client2: StandardHost;
connections:
client1.ethg++ <–> Eth100M <–> relayServer.ethg++;
relayServer.ethg++ <–> Eth100M <–> server2.ethg++;
server2.ethg++ <–> Eth100M <–> client2.ethg++;
}
7.2: Handle SMTP Errors and Retries
Incorporate to help for SMTP error handling, like retrying email delivery if a server is down or responding with errors such as “550 Mailbox Unavailable”.
if (serverDown) {
cMessage *error = new cMessage(“550 Mailbox Unavailable”);
send(error, “ethg$o”);
}
7.3: Introduce Latency and Queuing
Replicate network delays or server-side email queuing to track how SMTP manage congested networks or busy mail servers.
*.server1.eth[0].delay = 10ms # Introduce a 10ms delay on the link to server1
7.4: Simulate Mailbox Delivery
We can prolong the SMTPServer to store incoming emails in a mailbox, replicating an email delivery for client-side applications.
In the end of the simulation, we all learn and get knowledge about the Simple Mail Transfer Protocol that is used for communication through email was simulated in OMNeT++ simulation tool. We will elaborate on the Simple Mail Transfer Protocol strategy applied in different simulation instances in further manual.
