Packet Tracer VPN Simulation (PTVS)


PTVS:   SOLD       



Objective:

  • Students can understand the concept of VPN implementation.
  • Students can comprehend the concept of VPN in computer networks.
  • Students can design a VPN within a computer network.
  • Students can simulate a VPN using Packet Tracer.

Introduction:

A Virtual Private Network (VPN) is a mechanism for connecting two nodes in a network via another network, typically the internet. A VPN ensures private data transmission by encrypting the data packets, providing security even when using a public medium. The primary purpose of a VPN is to protect data traffic from being intercepted or modified by unauthorized entities.

VPN technology operates as software on both ends of the connection and provides a private connection, even though it uses public infrastructure. This privacy ensures that only authorized users can access the network. VPN uses tunneling, a method where data packets travel through a secure "tunnel" between two endpoints.


Applications of VPN Tunneling:

  1. Remote Access Client Connections: Enables remote access from home computers to office networks via the internet.
  2. LAN-to-LAN Internetworking: Connects multiple networks in separate locations, making them appear as a single network.
  3. Access Control in Intranet: Ensures data transmitted within an intranet remains private and inaccessible to unauthorized users.

VPN Tunneling Protocols:

  1. Point-to-Point Tunneling Protocol (PPTP): A Microsoft-developed protocol operating at Layer 2 of the OSI model.
  2. Layer Two Tunneling Protocol (L2TP): An enhancement over PPTP, developed by Cisco, operating at Layer 2.
  3. Internet Protocol Security (IPSec): Works at Layer 3 and is widely supported by various vendors for secure data exchange.
  4. Secure Socket Layer (SSL)/Transport Layer Security (TLS): Operates at the transport layer and is commonly used in open-source applications.



Practical Steps:

A. Network Setup Simulation:

  1. Create a network simulation according to the given topology.

B. Configure the AAA Server:

  1. Set the IP gateway to 10.2.0.1, assign the IP 10.2.0.2.
  2. Configure DHCP and DNS on the AAA server.
  3. Configure the server as a VPN server.

C. VPN Router Configuration:

  1. Access the router configuration terminal and run the following commands:
    ```bash Router>enable
    Router#configure terminal

hostname Router
aaa new-model
aaa authentication login VPNAUTH group radius local
aaa authorization network VPNAUTH local

crypto isakmp policy 10
encr aes 256
authentication pre-share
group 2

crypto isakmp client configuration group ciscogroup
key ciscogroup
pool VPNCLIENTS
netmask 255.255.255.0

crypto ipsec transform-set mytrans esp-3des esp-sha-hmac
crypto dynamic-map mymap 10
set transform-set mytrans
reverse-route

crypto map mymap client authentication list VPNAUTH
crypto map mymap isakmp authorization list VPNAUTH
crypto map mymap client configuration address respond
crypto map mymap 10 ipsec-isakmp dynamic mymap

ip local pool VPNCLIENTS 10.1.1.100 10.1.1.200
ip route 10.0.0.0 255.255.255.0 10.3.0.2
radius-server host 10.2.0.2 auth-port 1645 key cisco

2. Save the configuration:  
```bash
Router#wr


D. Testing VPN Connectivity:

  1. Test the connection with the ping command:
    Router#ping 10.2.0.2

E. Client Router Configuration:

  1. Set up the client router with appropriate IP addresses and routes.
  2. Configure the PC on the client side with an IP address within the 10.0.0.0/24 network and gateway 10.0.0.1.

F. VPN Client Configuration:

  1. Configure the dial-up VPN settings on the client PC:
    • Group Name: ciscogroup
    • Group Key: ciscogroup
    • Server IP: 10.3.0.1
    • Username: user
    • Password: pass


By following these steps, a secure VPN tunnel can be established between two networks using Packet Tracer, allowing for encrypted data transmission across public networks.

Understanding Virtual Private Network (VPN)

In the world of the internet and intranet, various technologies have developed rapidly, both in local and non-local networks. The internet is widely used by companies, business groups, organizations, and individuals. This is due to the widespread use of the internet in Indonesia as both a source of information and a platform to provide it, especially in the business sector. However, it is essential to recognize that intranet technology is also thriving, particularly among business owners who take their operations online. One key technology used in intranet systems is the VPN or Virtual Private Network.

From a network perspective, one of the main issues with the internet (public IP) is the lack of robust security support. From a business perspective, IP is essential for data exchange between branch offices or with corporate partners. VPNs were developed to address these issues. A VPN allows a corporate network to connect to its branch offices using private addressing while securing data transmission. Four primary protocols are commonly used to implement VPNs over the internet:

  1. Point-to-Point Tunneling Protocol (PPTP)
  2. Layer-2 Forwarding (L2F)
  3. Layer-2 Tunneling Protocol (L2TP)
  4. IP Security Protocol (IPSec)


IPSec has become the standard for VPN implementation as it is well-suited for IP environments compared to PPTP, L2F, and L2TP, which are more applicable in multi-protocol environments like NetBEUI, IPX, or AppleTalk. Additionally, encryption, authentication, and key management are integral components of IPSec.

The Role of VPNs in Intranet Security

The following section explains how VPN technology enhances security for businesses with multiple branches and explores its capabilities.

About VPN

Modern business demands are supported by a wide variety of communication networks. Employees in companies access corporate resources through their organization's communication networks. Additionally, business partners may access these resources using different networks to collaborate on information sharing, business planning, and more. Traditionally, companies used leased lines or frame relay circuits to connect headquarters with branch offices. However, these methods are inflexible, especially for businesses that need quick communication networks with partners or mobile employees working on field projects.

VPNs leverage the existing internet infrastructure to address these networking challenges. Unlike leased lines or frame relay, VPNs use the internet to facilitate data exchange between a company’s headquarters and its branches. A brief overview of VPNs is shown in Figures 4.1 and 4.2.

Gambar 4.1. Private Network Menggunakan Leased Lines
Figure 4.1: Private Network Using Leased Lines

(Illustration of a private network relying on leased lines for connectivity.)

Gambar 4.2. Private Network Menggunakan Public Internet
Figure 4.2: Private Network Using Public Internet

(Illustration of a private network using public internet as its transport medium.)

From a network perspective, public IP networks face security challenges, while businesses view IP as essential for data exchange between branches or partners. VPNs address this by creating private addressing with secure data transmission.

VPN Protocols

Four main protocols are typically used to implement VPNs over the internet:

  1. Point-to-Point Tunneling Protocol (PPTP)
  2. Layer-2 Forwarding (L2F)
  3. Layer-2 Tunneling Protocol (L2TP)
  4. IP Security Protocol (IPSec)


IPSec has become the standard for VPNs because it is better suited for IP-based environments, unlike PPTP, L2F, and L2TP, which are more compatible with non-IP protocols like NetBEUI, IPX, and AppleTalk. Moreover, encryption, authentication, and key management are integral to IPSec's functionality.


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