NETGEAR FVS124G Router Manual PDF (Setup & Configuration Guide)

Home

Manuals

NETGEAR

FVS124G

Page 216 / 238 Scroll up to view Page 211 - 215

Reference Manual for the ProSafe VPN Firewall 25 with 4 Gigabit LAN and Dual WAN Ports

D-2

Virtual Private Networking

202-10085-01, March 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 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 217 / 238

Reference Manual for the ProSafe VPN Firewall 25 with 4 Gigabit LAN and Dual WAN Ports

Virtual Private Networking

D-3

202-10085-01, March 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 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/

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 9-4:

Original packet and packet with IPSec Encapsulated Security Payload

Page 218 / 238

Reference Manual for the ProSafe VPN Firewall 25 with 4 Gigabit LAN and Dual WAN Ports

D-4

Virtual Private Networking

202-10085-01, March 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 9-5:

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 what 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.

Page 219 / 238

Reference Manual for the ProSafe VPN Firewall 25 with 4 Gigabit LAN and Dual WAN Ports

Virtual Private Networking

D-5

202-10085-01, March 2005

Mode

SAs operate using modes. A mode is the method in which the IPSec protocol is applied to the

packet. IPSec can be used in tunnel mode or transport mode. Typically, the tunnel mode is used for

gateway-to-gateway IPSec tunnel protection, while transport mode is used for host-to-host IPSec

tunnel protection. A gateway is a device that monitors and manages incoming and outgoing

network traffic and routes the traffic accordingly. A host is a device that sends and receives

network traffic.

•

Transport Mode:

The transport mode IPSec implementation encapsulates only the packet’s

payload. The IP header is not changed. After the packet is processed with IPSec, the new IP

packet contains the old IP header (with the source and destination IP addresses unchanged)

and the processed packet payload. Transport mode does not shield the information in the IP

header; therefore, an attacker can learn where the packet is coming from and where it is going

to. The previous packet diagrams show a packet in transport mode.

•

Tunnel Mode:

The tunnel mode IPSec implementation encapsulates the entire IP packet. The

entire packet becomes the payload of the packet that is processed with IPSec. A new IP header

is created that contains the two IPSec gateway addresses. The gateways perform the

encapsulation/decapsulation on behalf of the hosts. Tunnel mode ESP prevents an attacker

from analyzing the data and deciphering it, as well as knowing who the packet is from and

where it is going.

Note:

AH and ESP can be used in both transport mode or tunnel mode.

Figure 9-6:

Original packet and packet with IPSec ESP in Tunnel mode

Page 220 / 238

Reference Manual for the ProSafe VPN Firewall 25 with 4 Gigabit LAN and Dual WAN Ports

D-6

Virtual Private Networking

202-10085-01, March 2005

Key Management

IPSec uses the Internet Key Exchange (IKE) protocol to facilitate and automate the SA setup and

the exchange of keys between parties transferring data. Using keys ensures that only the sender

and receiver of a message can access it.

IPSec requires that keys be re-created, or refreshed, frequently so that the parties can communicate

securely with each other. IKE manages the process of refreshing keys; however, a user can control

the key strength and the refresh frequency. Refreshing keys on a regular basis ensures data

confidentiality between sender and receiver.

Understand the Process Before You Begin

This TechNote provides case studies on how to configure a secure IPSec VPN tunnels. This

document assumes the reader has a working knowledge of NETGEAR management systems.

NETGEAR is a member of the VPN Consortium, a group formed to facilitate IPSec VPN vendor

interoperability. The VPN Consortium has developed specific scenarios to aid system

administrators in the often confusing process of connecting two different vendor implementations

of the IPSec standard. The case studies in this TechNote follow the addressing and configuration

mechanics defined by the VPN Consortium. Additional information regarding inter-vendor

interoperability may be found at

http://www.vpnc.org/interop.html

It is a good idea to gather all the necessary information required to establish a VPN before you

begin the configuration process. You should understand whether the firmware is up to date, all of

the addresses that will be necessary, and all of the parameters that need to be set on both sides. Try

to understand any incompatibilities before you begin, so that you minimize any potential

complications which may arise from normal firewall or WAN processes.

If you are not a full-time system administrator, it is a good idea to familiarize yourself with the

mechanics of a VPN. The brief description in this TechNote will help. Other good sources include:

•

The NETGEAR VPN Tutorial – http://www.netgear.com/planetvpn/pvpn_2.html

•

The VPN Consortium –

http://www.vpnc.org/

•

The VPN bibliography in

“Additional Reading” on page D-11

Rate

Popular NETGEAR Models

Famous Router IPs

Famous Router Companies

Bookmark Our Site

Share