NETGEAR WGR614v6 Router Manual PDF (Setup & Configuration Guide)

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Reference Manual for the 54 Mbps Wireless Router WGR614 v6

Wireless Networking Basics

D-9

202-10099-01, April 2005

WPA and WPA2 offer the following benefits:

•

Enhanced data privacy

•

Robust key management

•

Data origin authentication

•

Data integrity protection

The Wi-Fi Alliance is now performing interoperability certification testing on Wi-Fi Protected

Access products. Starting August of 2003, all new Wi-Fi certified products have to support WPA.

NETGEAR is implementing WPA and WPA2 on client and access point products. The 802.11i

standard was ratified in 2004.

How Does WPA Compare to WEP?

WEP is a data encryption method and is not intended as a user authentication mechanism. WPA

user authentication is implemented using 802.1x and the Extensible Authentication Protocol

(EAP). Support for 802.1x authentication is required in WPA. In the 802.11 standard, 802.1x

authentication was optional. For details on EAP specifically, refer to IETF's RFC 2284.

With 802.11 WEP, all access points and client wireless adapters on a particular wireless LAN must

use the same encryption key. A major problem with the 802.11 standard is that the keys are

cumbersome to change. If you do not update the WEP keys often, an unauthorized person with a

sniffing tool can monitor your network for less than a day and decode the encrypted messages.

Products based on the 802.11 standard alone offer system administrators no effective method to

update the keys.

For 802.11, WEP encryption is optional. For WPA, encryption using Temporal Key Integrity

Protocol (TKIP) is required. TKIP replaces WEP with a new encryption algorithm that is stronger

than the WEP algorithm, but that uses the calculation facilities present on existing wireless devices

to perform encryption operations. TKIP provides important data encryption enhancements

including a per-packet key mixing function, a message integrity check (MIC) named Michael, an

extended initialization vector (IV) with sequencing rules, and a re-keying mechanism. Through

these enhancements, TKIP addresses most of the known WEP vulnerabilities.

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How Does WPA Compare to WPA2 (IEEE 802.11i)?

WPA is forward compatible with the WPA2 security specification. WPA is a subset of WPA2 and

used certain pieces of the early 802.11i draft, such as 802.1x and TKIP. The main pieces of WPA2

that are not included in WPA are secure IBSS (Ad-Hoc mode), secure fast handoff (for specialized

802.11 VoIP phones), as well as enhanced encryption protocols, such as AES-CCMP. These

features were either not yet ready for market or required hardware upgrades to implement.

What are the Key Features of WPA and WPA2 Security?

The following security features are included in the WPA and WPA2 standard:

•

WPA and WPA2 Authentication

•

WPA and WPA2 Encryption Key Management

–

Temporal Key Integrity Protocol (TKIP)

–

Michael message integrity code (MIC)

–

AES support (WPA2, requires hardware support)

•

Support for a mixture of WPA, WPA2, and WEP wireless clients to allow a migration strategy,

but mixing WEP and WPA/WPA2 is discouraged

These features are discussed below.

WPA/WPA2 addresses most of the known WEP vulnerabilities and is primarily intended for

wireless infrastructure networks as found in the enterprise. This infrastructure includes stations,

access points, and authentication servers (typically RADIUS servers). The RADIUS server holds

(or has access to) user credentials (for example, user names and passwords) and authenticates

wireless users before they gain access to the network.

The strength of WPA/WPA2 comes from an integrated sequence of operations that encompass

802.1X/EAP authentication and sophisticated key management and encryption techniques. Its

major operations include:

•

Network security capability determination. This occurs at the 802.11 level and is

communicated through WPA information elements in Beacon, Probe Response, and (Re)

Association Requests. Information in these elements includes the authentication method

(802.1X or Pre-shared key) and the preferred cipher suite (WEP, TKIP, or AES).

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Reference Manual for the 54 Mbps Wireless Router WGR614 v6

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The primary information conveyed in the Beacon frames is the authentication method and the

cipher suite. Possible authentication methods include 802.1X and Pre-shared key. Pre-shared

key is an authentication method that uses a statically configured pass phrase on both the

stations and the access point. This obviates the need for an authentication server, which in

many home and small office environments will not be available nor desirable. Possible cipher

suites include: WEP, TKIP, and AES (Advanced Encryption Standard). We talk more about

TKIP and AES when addressing data privacy below.

•

Authentication. EAP over 802.1X is used for authentication. Mutual authentication is gained

by choosing an EAP type supporting this feature and is required by WPA. 802.1X port access

control prevents full access to the network until authentication completes. 802.1X

EAPOL-Key packets are used by WPA to distribute per-session keys to those stations

successfully authenticated.

The supplicant in the station uses the authentication and cipher suite information contained in

the information elements to decide which authentication method and cipher suite to use. For

example, if the access point is using the pre-shared key method then the supplicant need not

authenticate using full-blown 802.1X. Rather, the supplicant must simply prove to the access

point that it is in possession of the pre-shared key. If the supplicant detects that the service set

does not contain a WPA information element then it knows it must use pre-WPA 802.1X

authentication and key management in order to access the network.

•

Key management. WPA/WPA2 features a robust key generation/management system that

integrates the authentication and data privacy functions. Keys are generated after successful

authentication and through a subsequent 4-way handshake between the station and Access

Point (AP).

•

Data Privacy (Encryption). Temporal Key Integrity Protocol (TKIP) is used to wrap WEP in

sophisticated cryptographic and security techniques to overcome most of its weaknesses.

•

Data integrity. TKIP includes a message integrity code (MIC) at the end of each plaintext

message to ensure messages are not being spoofed.

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WPA/WPA2 Authentication: Enterprise-level User

Authentication via 802.1x/EAP and RADIUS

Figure 4-3:

WPA/WPA2 Overview

IEEE 802.1x offers an effective framework for authenticating and controlling user traffic to a

protected network, as well as providing a vehicle for dynamically varying data encryption keys via

EAP from a RADIUS server, for example. This framework enables using a central authentication

server, which employs mutual authentication so that a rogue wireless user does not join the

network.

It is important to note that 802.1x does not provide the actual authentication mechanisms. When

using 802.1x, the EAP type, such as Transport Layer Security (EAP-TLS), or EAP Tunneled

Transport Layer Security (EAP-TTLS), defines how the authentication takes place.

Note

: For environments with a Remote Authentication Dial-In User Service (RADIUS)

infrastructure, WPA supports Extensible Authentication Protocol (EAP). For environments

without a RADIUS infrastructure, WPA supports the use of a pre-shared key.

Together, these technologies provide a framework for strong user authentication.

Windows XP implements 802.1x natively, and several NETGEAR switch and wireless access

point products support 802.1x.

Certificate

Authority

(for

example

Win Server,

VeriSign)

WPA/WPA2

enabled

wireless

client with

“supplicant”

TCP/IP

Ports Closed

Until

Authenticated

RADIUS Server

Wired Network with Optional

802.1x Port Based Network

Access Control

WPA/WPA2

enabled

Access Point

using

pre-shared key

or

802.1x

TCP/IP

Ports Opened

After

Authenticated

Wireless LAN

Login

Authentication

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Reference Manual for the 54 Mbps Wireless Router WGR614 v6

Wireless Networking Basics

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Figure 4-4:

802.1x Authentication Sequence

The AP sends Beacon Frames with WPA/WPA2 information element to the stations in the service

set. Information elements include the required authentication method (802.1x or Pre-shared key)

and the preferred cipher suite (WEP, TKIP, or AES). Probe Responses (AP to station) and

Association Requests (station to AP) also contain WPA information elements.

1.

Initial 802.1x communications begin with an unauthenticated supplicant (client device)

attempting to connect with an authenticator (802.11 access point). The client sends an

EAP-start message. This begins a series of message exchanges to authenticate the client.

2.

The access point replies with an EAP-request identity message.

1

2

3

4

5

6

7

Client with a WPA/

WPA2-enabled wireless

adapter and supplicant

(Win XP, Funk,

Meetinghouse)

For example, a

WPA/WPA2-enabled

AP

For example, a

RADIUS server

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