NETGEAR FVS114 Router Manual PDF (Setup & Configuration Guide)

Page 166 / 212 Scroll up to view Page 161 - 165

Reference Manual for the ProSafe VPN Firewall FVS114

B-16

Network, Routing, and Firewall Basics

202-10098-01, April 2005

Page 167 / 212

Virtual Private Networking

C-1

202-10098-01, April 2005

Appendix C

Virtual Private Networking

There have been many improvements in the Internet including Quality of Service, network

performance, and inexpensive technologies, such as DSL. But one of the most important advances

has been in Virtual Private Networking (VPN) Internet Protocol security (IPSec). IPSec is one of

the most complete, secure, and commercially available, standards-based protocols developed for

transporting data.

What is a VPN?

A VPN is a shared network where private data is segmented from other traffic so that only the

intended recipient has access. The term VPN was originally used to describe a secure connection

over the Internet. Today, however, VPN is also used to describe private networks, such as Frame

Relay, Asynchronous Transfer Mode (ATM), and Multiprotocol Label Switching (MPLS).

A key aspect of data security is that the data flowing across the network is protected by encryption

technologies. Private networks lack data security; so data attackers can tap directly into the

network and read the data. IPSec-based VPNs use encryption to provide data security, which

increases the network’s resistance to data tampering or theft.

IPSec-based VPNs can be created over any type of IP network, including the Internet, Frame

Relay, ATM, and MPLS, but only the Internet is ubiquitous and inexpensive.

VPNs are traditionally used for:

•

Intranets:

Intranets connect an organization’s locations. These locations range from the

headquarters offices, to branch offices, to a remote employee’s home. Often this connectivity

is used for e-mail and for sharing applications and files. While Frame Relay, ATM, and MPLS

accomplish these tasks, the shortcomings of each limits connectivity. The cost of connecting

home users is also very expensive compared to Internet-access technologies, such as DSL or

cable. Because of this, organizations are moving their networks to the Internet, which is

inexpensive, and using IPSec to create these networks.

Page 168 / 212

Reference Manual for the ProSafe VPN Firewall FVS114

C-2

Virtual Private Networking

202-10098-01, April 2005

•

Remote Access:

Remote access enables telecommuters and mobile workers to access e-mail

and business applications. A dial-up connection to an organization’s modem pool is one

method of access for remote workers, but is expensive because the organization must pay the

associated long distance telephone and service costs. Remote access VPNs greatly reduce

expenses by enabling mobile workers to dial a local Internet connection and then set up a

secure IPSec-based VPN communications to their organization.

•

Extranets

: Extranets are secure connections between two or more organizations. Common

uses for extranets include supply-chain management, development partnerships, and

subscription services. These undertakings can be difficult using legacy network technologies

due to connection costs, time delays, and access availability. IPSec-based VPNs are ideal for

extranet connections. IPSec-capable devices can be quickly and inexpensively installed on

existing Internet connections.

What Is IPSec and How Does It Work?

IPSec is an Internet Engineering Task Force (IETF) standard suite of protocols that provides data

authentication, integrity, and confidentiality as data is transferred between communication points

across IP networks. IPSec provides data security at the IP packet level. A packet is a data bundle

that is organized for transmission across a network, and includes a header and payload (the data in

the packet). IPSec emerged as a viable network security standard because enterprises wanted to

ensure that data could be securely transmitted over the Internet. IPSec protects against possible

security exposures by protecting data while in transit.

IPSec Security Features

IPSec is the most secure method commercially available for connecting network sites. IPSec was

designed to provide the following security features when transferring packets across networks:

•

Authentication:

Verifies that the packet received is actually from the claimed sender.

•

Integrity:

Ensures that the contents of the packet did not change in transit.

•

Confidentiality:

Conceals the message content through encryption.

IPSec Components

IPSec contains the following elements:

Page 169 / 212

Reference Manual for the ProSafe VPN Firewall FVS114

Virtual Private Networking

C-3

202-10098-01, April 2005

•

Encapsulating Security Payload (ESP)

: Provides confidentiality, authentication, and

integrity.

•

Authentication Header (AH)

: Provides authentication and integrity.

•

Internet Key Exchange (IKE)

: Provides key management and Security Association (SA)

management.

Encapsulating Security Payload (ESP)

ESP provides authentication, integrity, and confidentiality, which protect against data tampering

and, most importantly, provide message content protection.

IPSec provides an open framework for implementing industry standard algorithms, such as SHA

and MD5. The algorithms that IPSec uses produce a unique and unforgeable identifier for each

packet, which is a data equivalent of a fingerprint. This fingerprint allows the device to determine

if a packet has been tampered with. Furthermore, packets that are not authenticated are discarded

and not delivered to the intended receiver.

ESP also provides all encryption services in IPSec. Encryption translates a readable message into

an unreadable format to hide the message content. The opposite process, called decryption,

translates the message content from an unreadable format to a readable message. Encryption and

decryption allows only the sender and the authorized receiver to read the data. In addition, ESP has

an option to perform authentication, called ESP authentication. Using ESP authentication, ESP

provides authentication and integrity for the payload and not for the IP header.

Figure C-1:

Original packet and packet with IPSec Encapsulated Security Payload

Page 170 / 212

Reference Manual for the ProSafe VPN Firewall FVS114

C-4

Virtual Private Networking

202-10098-01, April 2005

The ESP header is inserted into the packet between the IP header and any subsequent packet

contents. However, because ESP encrypts the data, the payload is changed. ESP does not encrypt

the ESP header, nor does it encrypt the ESP authentication.

Authentication Header (AH)

AH provides authentication and integrity, which protect against data tampering, using the same

algorithms as ESP. AH also provides optional anti-replay protection, which protects against

unauthorized retransmission of packets. The authentication header is inserted into the packet

between the IP header and any subsequent packet contents. The payload is not touched.

Although AH protects the packet’s origin, destination, and contents from being tampered with, the

identity of the sender and receiver is known. In addition, AH does not protect the data’s

confidentiality. If data is intercepted and only AH is used, the message contents can be read. ESP

protects data confidentiality. For added protection in certain cases, AH and ESP can be used

together. In the following table, IP HDR represents the IP header and includes both source and

destination IP addresses.

Figure C-2:

Original packet and packet with IPSec Authentication Header

IKE Security Association

IPSec introduces the concept of the Security Association (SA). An SA is a logical connection

between two devices transferring data. An SA provides data protection for unidirectional traffic by

using the defined IPSec protocols. An IPSec tunnel typically consists of two unidirectional SAs,

which together provide a protected, full-duplex data channel.

The SAs allow an enterprise to control exactly which resources may communicate securely,

according to security policy. To do this an enterprise can set up multiple SAs to enable multiple

secure VPNs, as well as define SAs within the VPN to support different departments and business

partners.

Rate

Popular NETGEAR Models

Famous Router IPs

Famous Router Companies

Bookmark Our Site

Share