Netgear Router WGR614 V6 User Manual

							Reference Manual for the 54 Mbps Wireless Router WGR614 v6
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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 IETFs 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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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,
Ve r i S i g n )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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202-10099-01, April 2005 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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3.The client sends an EAP-response packet containing the identity to the authentication server. 
The access point responds by enabling a port for passing only EAP packets from the client to 
an authentication server located on the wired side of the access point. The access point blocks 
all other traffic, such as HTTP, DHCP, and POP3 packets, until the access point can verify the 
clients identity using an authentication server (for example, RADIUS). 
4.The authentication server uses a specific authentication algorithm to verify the clients identity. 
This could be through the use of digital certificates or some other EAP authentication type. 
5.The authentication server will either send an accept or reject message to the access point. 
6.The access point sends an EAP-success packet (or reject packet) to the client. 
7.If the authentication server accepts the client, then the access point will transition the clients 
port to an authorized state and forward additional traffic. 
The important part to know at this point is that the software supporting the specific EAP type 
resides on the authentication server and within the operating system or application “supplicant” 
software on the client devices. The access point acts as a “pass through” for 802.1x messages, 
which means that you can specify any EAP type without needing to upgrade an 802.1x-compliant 
access point. As a result, you can update the EAP authentication type to such devices as token 
cards (Smart Cards), Kerberos, one-time passwords, certificates, and public key authentication, or 
as newer types become available and your requirements for security change. 
WPA/WPA2 Data Encryption Key Management
With 802.1x, the rekeying of unicast encryption keys is optional. Additionally, 802.11 and 802.1x 
provide no mechanism to change the global encryption key used for multicast and broadcast 
traffic. With WPA/WPA2, rekeying of both unicast and global encryption keys is required. 
For the unicast encryption key, the Temporal Key Integrity Protocol (TKIP) changes the key for 
every frame, and the change is synchronized between the wireless client and the wireless access 
point (AP). For the global encryption key, WPA includes a facility (the Information Element) for 
the wireless AP to advertise the changed key to the connected wireless clients.
If configured to implement dynamic key exchange, the 802.1x authentication server can return 
session keys to the access point along with the accept message. The access point uses the session 
keys to build, sign and encrypt an EAP key message that is sent to the client immediately after 
sending the success message. The client can then use contents of the key message to define 
applicable encryption keys. In typical 802.1x implementations, the client can automatically change 
encryption keys as often as necessary to minimize the possibility of eavesdroppers having enough 
time to crack the key in current use.  
						

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Temporal Key Integrity Protocol (TKIP)
WPA uses TKIP to provide 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. TKIP also provides for the 
following: 
• The verification of the security configuration after the encryption keys are determined. 
• The synchronized changing of the unicast encryption key for each frame. 
• The determination of a unique starting unicast encryption key for each preshared key 
authentication.
Michael
With 802.11 and WEP, data integrity is provided by a 32-bit integrity check value (ICV) that is 
appended to the 802.11 payload and encrypted with WEP. Although the ICV is encrypted, you can 
use cryptanalysis to change bits in the encrypted payload and update the encrypted ICV without 
being detected by the receiver.
With WPA, a method known as Michael specifies a new algorithm that calculates an 8-byte 
message integrity check (MIC) using the calculation facilities available on existing wireless 
devices. The MIC is placed between the data portion of the IEEE 802.11 frame and the 4-byte ICV. 
The MIC field is encrypted together with the frame data and the ICV.
Michael also provides replay protection. A new frame counter in the IEEE 802.11 frame is used to 
prevent replay attacks.
AES Support for WPA2
One of the encryption methods supported by WPA2 is the advanced encryption standard (AES), 
although AES support will not be required initially for Wi-Fi certification. This is viewed as the 
optimal choice for security conscience organizations, but the problem with AES is that it requires a 
fundamental redesign of the NIC’s hardware in both the station and the access point. TKIP is a 
pragmatic compromise that allows organizations to deploy better security while AES capable 
equipment is being designed, manufactured, and incrementally deployed. 
						

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Is WPA/WPA2 Perfect?
WPA/WPA2 is not without its vulnerabilities. Specifically, it is susceptible to denial of service 
(DoS) attacks. If the access point receives two data packets that fail the message integrity code 
(MIC) within 60 seconds of each other, then the network is under an active attack, and as a result, 
the access point employs counter measures, which include disassociating each station using the 
access point. This prevents an attacker from gleaning information about the encryption key and 
alerts administrators, but it also causes users to lose network connectivity for 60 seconds. More 
than anything else, this may just prove that no single security tactic is completely invulnerable. 
WPA/WPA2 is a definite step forward in WLAN security over WEP and has to be thought of as a 
single part of an end-to-end network security strategy.
Product Support for WPA/WPA2
Starting in August, 2003, NETGEAR, Inc. wireless Wi-Fi certified products will support the WPA 
standard. NETGEAR, Inc. wireless products that had their Wi-Fi certification approved before 
August, 2003 will have one year to add WPA so as to maintain their Wi-Fi certification.
WPA/WPA2 requires software changes to the following: 
• Wireless access points 
• Wireless network adapters 
• Wireless client programs
Supporting a Mixture of WPA, WPA2, and WEP Wireless Clients is Discouraged
To support the gradual transition of WEP-based wireless networks to WPA/WPA2, a wireless AP 
can support both WEP and WPA/WPA2 clients at the same time. During the association, the 
wireless AP determines which clients use WEP and which clients use WPA/WPA2. The 
disadvantage to supporting a mixture of WEP and WPA/WPA2 clients is that the global encryption 
key is not dynamic. This is because WEP-based clients cannot support it. All other benefits to the 
WPA clients, such as integrity, are maintained.
However, a mixed mode supporting WPA/WPA2 and non-WPA/WPA2 clients would offer 
network security that is no better than that obtained with a non-WPA/WPA2 network, and thus this 
mode of operation is discouraged. 
						

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Changes to Wireless Access Points
Wireless access points must have their firmware updated to support the following: 
•The new WPA/WPA2 information element 
To advertise their support of WPA/WPA2, wireless APs send the beacon frame with a new 
802.11 WPA/WPA2 information element that contains the wireless APs security configuration 
(encryption algorithms and wireless security configuration information). 
•The WPA/WPA2 two-phase authentication 
Open system, then 802.1x (EAP with RADIUS or preshared key). 
•TKIP 
•Michael 
•AES (WPA2)
To upgrade your wireless access points to support WPA/WPA2, obtain a WPA/WPA2 firmware 
update from your wireless AP vendor and upload it to your wireless AP.
Changes to Wireless Network Adapters
Wireless networking software in the adapter, and possibly in the OS or client application, must be 
updated to support the following: 
•The new WPA/WPA2 information element 
Wireless clients must be able to process the WPA/WPA2 information element and respond 
with a specific security configuration. 
•The WPA/WPA2 two-phase authentication  
Open system, then 802.1x supplicant (EAP or preshared key). 
•TKIP 
•Michael 
•AES (WPA2)
To upgrade your wireless network adapters to support WPA/WPA2, obtain a WPA/WPA2 update 
from your wireless network adapter vendor and update the wireless network adapter driver.
For Windows wireless clients, you must obtain an updated network adapter driver that supports 
WPA. For wireless network adapter drivers that are compatible with Windows XP (Service Pack 1) 
and Windows Server 2003, the updated network adapter driver must be able to pass the adapters 
WPA capabilities and security configuration to the Wireless Zero Configuration service.  
						

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Microsoft has worked with many wireless vendors to embed the WPA driver update in the wireless 
adapter driver. So, to update your Microsoft Windows wireless client, all you have to do is obtain 
the new WPA/WPA2-compatible driver and install the driver. 
Changes to Wireless Client Programs
Wireless client programs must be updated to permit the configuration of WPA/WPA2 
authentication (and preshared key) and the new WPA/WPA2 encryption algorithms (TKIP and 
AES).
To obtain the Microsoft WPA client program, visit the Microsoft Web site.
Note: The Microsoft WPA2 client is still in beta.