How to Simulate Virtual Private Networks Projects OMNeT++

To simulate Virtual Private Networks (VPNs) using OMNeT++ has needs to generate a secure communication tunnel over a public or private network usually using encryption and tunnelling protocols. To replicate VPNs in OMNeT++, we will required to design the network, execute encryption protocols, setup VPN tunnels, and create traffic among remote sites through the VPN.

Below is a step-by-step guide to help you simulate VPN projects using OMNeT++:

Steps to Simulate Virtual Private Networks Projects in OMNeT++

  1. Install OMNeT++
  • First, download and install OMNeT++.
  • Validate the installation by processing the example simulations delivered with OMNeT++.
  1. Install and Set Up the INET Framework
  • The INET framework is needed to replicate network protocols, encryption, and tunnelling for VPNs. It contains modules for routers, hosts, encryption, and secure communication.
  • Download the INET framework from the INET GitHub repository and install it as per the provided instructions.
  1. Understand VPN Concepts
  • VPNs (Virtual Private Networks) permit secure communication by encrypting data sent through public or private networks. VPNs are usually utilized to connect remote sites or users securely to a corporate network.
  • VPNs usually utilize tunnelling protocols such as IPSec, SSL, or GRE and implement encryption algorithms such as AES or DES for security.
  1. Design the VPN Network Topology
  • The VPN topology usually contain multiple sites associated through a public network (such as the internet), with VPN tunnels introduced among them. These tunnels are configure through VPN gateways or routers.

Example of a basic VPN topology in a NED file:

network VPNNetwork {

submodules:

vpnGatewayA: Router {

@display(“p=100,100;i=router”);

}

vpnGatewayB: Router {

@display(“p=400,100;i=router”);

}

internet: InternetCloud {

@display(“p=250,200”);

}

lanA: LAN {

@display(“p=50,250”);

}

lanB: LAN {

@display(“p=450,250”);

}

connections:

vpnGatewayA.pppg++ <–> EthernetLink <–> internet.pppg++;

vpnGatewayB.pppg++ <–> EthernetLink <–> internet.pppg++;

lanA.switch.pppg++ <–> EthernetLink <–> vpnGatewayA.pppg++;

lanB.switch.pppg++ <–> EthernetLink <–> vpnGatewayB.pppg++;

}

This configuration describes two VPN gateways (vpnGatewayA and vpnGatewayB) that associate LAN A and LAN B over a simulated internet cloud.

  1. Implement VPN Tunneling and Encryption

To replicate VPNs in OMNeT++, we need to execute tunneling protocols and encryption mechanisms. Common VPN scenario utilizes IPSec (Internet Protocol Security) for encryption and GRE (Generic Routing Encapsulation) for tunneling.

  • Tunneling: Wrap original packets inside another protocol such as encapsulate an IP packet inside another IP packet.
  • Encryption: Make sure secure communication among the VPN endpoints using encryption techniques such as AES (Advanced Encryption Standard) or DES (Data Encryption Standard).

GRE Tunneling Example:

We can describe a simple GRE-like tunnel by encapsulating IP packets in a custom tunnelling module:

class GreTunnel : public cSimpleModule {

protected:

virtual void handleMessage(cMessage *msg) override;

void encapsulatePacket(cMessage *msg);  // Encapsulate IP packet

void decapsulatePacket(cMessage *msg);  // Decapsulate IP packet

};

  • Encapsulation: Before transmitting a packet, encapsulate it into another IP packet, replicatting the GRE protocol.
  • Decapsulation: On receiving a packet, the VPN gateway decapsulates the packet and forwards it to the proper destination.

IPSec Encryption Example:

We can replicate IPSec encryption by executing encryption/decryption algorithms at both ends of the VPN tunnel:

class IPSecEncryption : public cSimpleModule {

protected:

virtual void handleMessage(cMessage *msg) override;

void encryptPacket(cMessage *msg);  // Encrypt outgoing packets

void decryptPacket(cMessage *msg);  // Decrypt incoming packets

};

Example AES encryption logic:

void IPSecEncryption::encryptPacket(cMessage *msg) {

// Apply AES encryption to the payload

}

void IPSecEncryption::decryptPacket(cMessage *msg) {

// Apply AES decryption to the payload

}

  1. Configure Routing Protocols for VPN Traffic

Routing protocols such as BGP (Border Gateway Protocol) or OSPF (Open Shortest Path First) can be utilized to direct traffic across the VPN tunnel among remote sites.

Example of configuring OSPF routing:

**.vpnGatewayA.routingTable.typename = “OspfRouting”

**.vpnGatewayB.routingTable.typename = “OspfRouting”

We can also set up static routes to direct specific traffic across the VPN tunnel. For instance, all traffic from LAN A destined for LAN B can be transmit across the VPN gateway.

  1. Simulate Traffic over the VPN Tunnel

To replicate traffic passing across the VPN, set up traffic generators (such as TCP, UDP, or HTTP applications) on the client hosts in the local networks.

Example UDP traffic configuration:

**.lanA.host[0].app[0].typename = “UdpBasicApp”

**.lanA.host[0].app[0].destAddr = “lanB.host[0]”

**.lanA.host[0].app[0].messageLength = 1024B

**.lanA.host[0].app[0].sendInterval = exponential(1s)

This configuration sends UDP traffic from a host in LAN A to a host in LAN B, encapsulating the traffic via the VPN tunnel and encoding it with IPSec.

  1. Configure Simulation Parameters

Describe metrics like link data rates, latency, encryption overhead, and tunnel characteristics in the .ini configuration file.

Example .ini configuration for VPN simulation:

network = VPNNetwork

sim-time-limit = 200s

# Internet link settings

**.internet.pppg++ <–> datarate = 100Mbps

**.internet.pppg++ <–> delay = 20ms

# IPSec and GRE tunnel settings

**.vpnGatewayA.pppg++ <–> GreTunnel

**.vpnGatewayB.pppg++ <–> GreTunnel

**.vpnGatewayA.encryption = “IPSecEncryption”

**.vpnGatewayB.encryption = “IPSecEncryption”

# OSPF routing protocol for VPN gateways

**.vpnGatewayA.routingTable.typename = “OspfRouting”

**.vpnGatewayB.routingTable.typename = “OspfRouting”

# Traffic generation (UDP)

**.lanA.host[0].app[0].typename = “UdpBasicApp”

**.lanA.host[0].app[0].destAddr = “lanB.host[0]”

**.lanA.host[0].app[0].messageLength = 1024B

**.lanA.host[0].app[0].sendInterval = exponential(1s)

  1. Run the Simulation and Visualize the VPN
  • Execute the simulation in OMNeT++ and monitor how traffic flows across the VPN tunnel.
  • Utilize OMNeT++’s visualization tools to display real-time packet forwarding among VPN gateways, encryption, and tunnelling behaviour.
  • Track packet encapsulation at the VPN gateways and monitor how traffic is securely transmitted among remote networks.

Enable visualization in the .ini file:

**.visualization.enabled = true

  1. Analyse Simulation Results

OMNeT++ delivered tools for collecting scalar and vector results, enabling you to measure key performance metrics such as:

  • End-to-End Latency: Evaluate the total delay experienced by packets traveling across the VPN tunnel.
  • Packet Overhead: Evaluate the additional overhead established by encryption and tunnelling protocols.
  • Bandwidth Utilization: track how much of the network bandwidth is consumed by VPN traffic.
  • Packet Loss and Errors: Evaluate packet loss and error rates in the period of transmission over the VPN tunnel.

Enable result recording in the .ini file:

**.scalar-recording = true

We can export the recorded outcomes for further analysis using external tools such as Python, MATLAB, or R.

Example .ini Configuration for VPN Simulation:

network = VPNNetwork

sim-time-limit = 300s

# Internet link settings

**.internet.pppg++ <–> datarate = 100Mbps

**.internet.pppg++ <–> delay = 20ms

# GRE and IPSec Tunnel settings

**.vpnGatewayA.pppg++ <–> GreTunnel

**.vpnGatewayB.pppg++ <–> GreTunnel

**.vpnGatewayA.encryption = “IPSecEncryption”

**.vpnGatewayB.encryption = “IPSecEncryption”

# OSPF routing protocol

**.vpnGatewayA.routingTable.typename = “OspfRouting”

**.vpnGatewayB.routingTable.typename = “OspfRouting”

# UDP traffic configuration

**.lanA.host[0].app[0].typename = “UdpBasicApp”

**.lanA.host[0].app[0].destAddr = “lanB.host[0]”

**.lanA.host[0].app[0].messageLength = 1024B

**.lanA.host[0].app[0].sendInterval = exponential(1s)

# Enable result recording and visualization

**.scalar-recording = true

**.visualization.enabled = true

  1. Extend and Customize the Simulation
  • Add SSL VPNs: We can expand the simulation by executing SSL-based VPNs (e.g., OpenVPN) and relate their performance with IPSec-based VPNs.
  • Test Different Encryption Algorithms: Replicate different encryption techniques such as AES, DES, and 3DES and measure their performance based on processing overhead and security.
  • Simulate Network Failures: Establish link or node failures to validate how well the VPN adjust and reroutes traffic in case of a network outage.

Advanced Features to Implement:

  • Multi-site VPNs: Connect multiple sites (LANs) using a single VPN hub or mesh VPN topology.
  • Dynamic Key Exchange: Execute IKE (Internet Key Exchange) to replicate dynamic key exchange for IPSec-based VPNs.
  • QoS and Traffic Shaping: Add Quality of Service (QoS) settings to select particular types of traffic across the VPN.

Through the entire process, you can acquire the simulation and execution process regarding the Virtual Private Networks project offered in it using OMNeT++ tool. We will plan to offer the more information regarding the Virtual Private Networks in another manual.

Contact phdprime.com, where we will provide support for comparative analysis and simulation assistance regarding Virtual Private Networks projects utilizing the OMNeT++ tool.

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