1. TCP/IP Protocol Suite 1 Upon completion you will be able to: Virtual Private Networks and Network Address Translation Understand the difference between an internet and an extranet Understand private, hybrid, and virtual private networks Understand how VPN can guarantee privacy Understand the mechanism of NAT Objectives

2. TCP/IP Protocol Suite 2 26.1 PRIVATE NETWORKS A private network is designed to be used only inside an organization. It allows access to shared resources and, at the same time, provides privacy. The topics discussed in this section include: IntranetExtranetAddressing

3. TCP/IP Protocol Suite 3 Table 26.1 Addresses for private networks

4. TCP/IP Protocol Suite 4 26.2 VIRTUAL PRIVATE NETWORKS (VPN) Virtual private network (VPN) is a technology for large organizations that use the global Internet for both intra- and interorganization communication, but require privacy in their intraorganization communication. The topics discussed in this section include: Achieving Privacy VPN Technology

5. TCP/IP Protocol Suite 5 Figure 26.1 Private network

6. TCP/IP Protocol Suite 6 Figure 26.2 Hybrid network

7. TCP/IP Protocol Suite 7 Figure 26.3 Virtual private network

8. TCP/IP Protocol Suite 8 Virtual private network A typical VPN might have a main LAN at the corporate headquarters of a company, other LANs at remote offices or facilities and individual users connecting from out in the field.LAN

9. TCP/IP Protocol Suite 9 VPN Types: Remote Access VPN Intranet VPN Extranet VPN

10. TCP/IP Protocol Suite 10 Remote-Access VPN Remote-Access VPN also called a virtual private dial-up network (VPDN), is a user-to-LAN connection used by a company that has employees who need to connect to the private network from various remote locations. Intranet-based - If a company has one or more remote locations that they wish to join in a single private network, they can create an intranet VPN to connect LAN to LAN. Extranet-based - When a company has a close relationship with another company (for example, a partner, supplier or customer), they can build an extranet VPN that connects LAN to LAN, and that allows all of the various companies to work in a shared environment.

11. TCP/IP Protocol Suite 11 Figure 26.4 Tunneling tunneling is the process of placing an entire packet within another packet and sending it over a network. You can place a packet that uses a protocol not supported on the Internet (such as NetBeui) inside an IP packet and send it safely over the Internet. Or you could put a packet that uses a private (non- routable) IP address inside a packet that uses a globally unique IP address to extend a private network over the Internet.globally unique IP address

12. TCP/IP Protocol Suite 12 Figure 26.5 Addressing in a VPN

13. TCP/IP Protocol Suite 13 26.3 NETWORK ADDRESS TRANSLATION (NAT) Network address translation (NAT) allows a site to use a set of private addresses for internal communication and a set of global Internet addresses for communication with another site. The site must have only one single connection to the global Internet through a router that runs NAT software. The topics discussed in this section include: Address Translation Translation Table NAT and ISP

14. TCP/IP Protocol Suite 14 Figure 26.6 NAT

15. TCP/IP Protocol Suite 15 Figure 26.7 Address translation

16. TCP/IP Protocol Suite 16 Figure 26.8 Translation

17. TCP/IP Protocol Suite 17 Table 26.2 Five-column translation table

18. TCP/IP Protocol Suite 18 Figure 26.9 An ISP and NAT