Wifi Standard And Security Computer Science Essay


WiFi (802.11b), has become the generally accepted means for implementing wireless local area networks in virtually every environment. Even though it was designed primarily for private applications, WiFi is also being deployed in public places to create so-called hotspots, Where WiFi-capable users can obtain broadband Internet access. Legal and security issues have continued to arise, unlike with wired networks wireless networks can easily be seen and access gained using the encryption key and this poses a threat to network reliability and information security. A look at various legal implications that might become relevant due to the deployment of WiFi roaming and discuss several risks and problems related to the security during the establishment of roaming connections between mobile devices and the Internet.

Keywords: WiFi , security


What is WiFi?

Institute of Electrical and Electronics Engineers in the year 1997.WiFi is also known as Wireless Fidelity which is a wireless technology that uses radio frequency for transmitting signals. WiFi is based on IEEE 802.11 standards; WiFi is a wireless technology which permits a PC, laptop, mobile, PDA to communicate with each other using the radio waves.

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The term WiFi includes any system that uses the 802.11 standard developed by the Wi-Fi is set up using Dynamic IPs, if the user does not know the IP of the Server at the location, Notebook or Desktop can still access the Internet through the Server at the location. WiFi is owned by the Wi-Fi Alliance. For establishing a Wi-Fi network connection, computer must be equipped with WiFi network cards that are connected wirelessly to the Internet using a wireless router, when the router is connected to the internet using the modem; the router uses the radio based technology to transmit the signals. To extend the signals the signal boosters are used to get a strong signal.

How does a WiFi Work?

Wi-Fi allocates internet/intranet connection globally and to be transmitted by the radio waves. A computer's wireless adapter translates data into a radio signal and transmits it using an antenna. A wireless router receives the signal and decodes it and the router sends the information to the Internet using a physical, wired Ethernet connection. Wi-Fi uses hotspots to connect to the internet. A hotspot is an internet access point that offers Internet access over a wireless local area network through the use of a router connected to an Internet service provider.

The below figure shows the pictorial representation of the working of the WiFi

wifi working

This article talks about the vision of global WiFi and identify the challenges which it faces in the real time. Here the focus on specific details and problems, a service scenario is chosen likely to be important to WiFi growth such as, security solution for 802.11-based networks, delivering broadband IP connectivity to the traveling professional, Wired Equivalent Privacy (WEP), received a great deal of coverage due to various technical failures in the protocol. Many users are rapidly adopting wireless networks because of the mobility and freedom which they provide. To address growing wireless network security problems the Standards bodies and industry organizations are spending a great deal of time and money on developing and deploying next-generation. The 802.11i IEEE draft standard provides next-generation authentication, authorization, and encryption capabilities. There are some new standards are more complicated than their predecessors but it is more secure than existing wireless networks. This also dramatically raises the number for attackers and administrators. The new standards will employ a phased adoption process because of the large installed base of 802.11 devices. The end result will provide users a secure base for mobile computing needs.

IEEE Standards for WiFi

Wireless LAN standards and amendments in which Intel is participating or has participated.

802.11 The original WLAN Standard. Supports 1 Mbps to 2 Mbps.

802.11a High speed WLAN standard for 5 GHz band. Supports 54 Mbps.

802.11b WLAN standard for 2.4 GHz band. Supports 11 Mbps.

802.11d International roaming - automatically configures devices to meet local RF regulations

802.11e Addresses quality of service requirements for all IEEE WLAN radio interfaces.

802.11f Defines inter-access point communications to facilitate multiple vendor-distributed WLAN networks.

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802.11g Establishes an additional modulation technique for 2.4 GHz band. Supports speeds up to 54 Mbps.

802.11h Defines the spectrum management of the 5 GHz band.

802.11k Defines and exposes radio and network information to facilitate radio resource management of a mobile Wireless LAN.

802.11n Provides higher throughput improvements. Intended to provide speeds up to 500 Mbps.

802.11s Defines how wireless devices can interconnect to create an ad-hoc (mesh) network.

802.11r Provides fast (<50 millisecond), secure and QoS-enabled inter-access point roaming protocol for clients.

802.11u Adds features to improve interworking with external (non-802) networks where the user is not pre-authorized for access.

802.11v Enhances client manageability, infrastructure assisted roaming management, and filtering services.

802.11z Creates tunnel direct link setup between clients to improve peer-peer video throughput.

802.11aa Robust video transport streaming.

The following table compares the various IEEE standards

Security Services


-To verify the identity of the communicating client stations

-One way; only station authenticated

-Open system authentication (No control)

-Shared-Key authentication (based on cryptography)


-To prevent information from eavesdropping

-Uses cryptographic technique like WEP

Access Control

-Denying unauthorised users from accessing resources

-Uses MAC address filtering, protocol filtering


-To ensure that messages are not modified between AP & clients

De-authentication Attack

The de-authentication frame is fakes by the attacker as if it was originated from the Access Point (AP). When the user gets the signal reception, the station disconnects and it tries to reconnect to the base station again. This process is repeated indefinitely to keep the station disconnected from the base station. The attacker can also set the receiving address to the broadcast address to target all stations associated with the victim base station. There are some wireless network cards that ignore this type of de-authentication frames.


Fragmentation Attack

The attacker sends a frame as a successive set of fragments. The access point will assemble them into a new frame and send it back to the wireless network. Since the attacker knows the

clear text of the frame, he can recover the key stream used to encrypt the frame. This process is repeated till he/she gets a 1500 long key stream. The attacker can use the key stream to

encrypt new frames or decrypt a frame that uses the same IV. The process can be repeated till the attacker builds a rainbow key stream table of all possible IVs. Such a table requires 23

GB of memory. More details of this attack can be found in [13].

WiFi Roaming Issues:

Security and legal liability:

For wireless communication networks to offer flexibility for the design of WiFi roaming solutions there is a large number of industrial standards and mechanisms are developed. It is a challenging research task to design good mechanisms for the realization of WiFi roaming in specific deployment environments such that the final solution is practical with respect to technological constraints and also it provides very good protection against security threats. Considering the security in WiFi sharing of the Connection leads to many risks and threats, this threat is not only for the network it is also for the mobile phones and the laptops. The various risks which could injection of malware, man in the middle, denial of service, sniffing of the confidential information that is communicated by the user


Let us denote the set of WiFi networks in the region that are involved in the roaming agreement By Nw = {Nw1, … , Nw n }. Let the network Nw a is be responsible for the administrative control over the set of WiFi access points A i = {A i,1, … , P i,n } and

WiFi enabled mobile devices Mdi = {Mdi,1, … ,Md i,o }. AU is the authentication authority which is an Internet service that can be questioned in order to authenticate a part of Network Nw. While in roaming the guest network is used to verify the authenticity of the home network Nwi of some mobile device Md i,k .It is most likely that AU can be used by Md i,k or Nwi to check whether the guest network Nw j is part of Network nw . The AU is the authentication authority is to be trusted in the sense that it correctly authenticates participating the Network Nw. Each of the service is administrated by one of the participating network.This service used in is a distributed hierarchy of AU servers, it may not be centralized.

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The following are the WiFi roaming problems in the Main phase:

Some device Md i,k , having a home network Nw i € Nw , moves into the area covered by a guest network Nwj € Nw and executes the admission procedure to obtain Internet access. In general, the whole process can be split into two phases described in the following.

The following are the WiFi roaming problems in the Registration phase:

The registration phase as an interactive protocol between Md i,k and Nw i at the end of which both parties establish some security association (SA), that is Md i,k and Nw i obtain some information that they can use later to recognize each other as a hosted device and a home network, respectively. The authentication authority AU is able to authenticate every network from Nw .

The following are the WiFi roaming problems in the Admission phase

WiFi roaming phase should be executed between Md i,k and a guest network Nw j. To setup the Internet connection for Md i,k is called the admission phase. The admission phase is considered as an interactive protocol

between Md i,k , Nw j , authentication authority AU and Nw i , which is invoked by the connection request of

Md i,k and at the end of which Nw j decides whether to accept this request or to

decline it. The two key arguments for the decision of Nw j are the authentication

of Nw i as part of NetworkNw and the authentication of Md i,k as an actual mobile node registered at Nw i .For the authentication of Nwi as a partner for roaming there are three possible options:

1)Nw j obtains authentication information directly from Md i,k with out having any authentication from AU

2) Nw j obtains authentication information directly from Nw i without interaction with AU . Nw j contacts AA which authenticates Nw i .For the authentication of the mobile device Md i,k as a device registered at Nw i , we consider two approaches :

Nw j obtains necessary authentication information directly from Md i,k without interaction with Nw i .

Nw j contacts Nw i which authenticates Md i,k .

Once admission phase has been performed, we distinguish between two scenarios depending on the way by which Md i,k is granted access to the Internet. In the fi rst WiFi roaming scenario we deal with considers a direct access, that is the Internet connection to Md i,k is granted directly by the guest network Nw j . Our second WiFi roaming scenario aims at a tunnel access such that Nw j opens a tunnel between Md i,k and its home network Nw i and the actual connection to the Internet is then granted by Nw i .

In the following we focus on the analysis of WiFi roaming admission Scenarios with direct and tunnel access modes from the perspective of Security requirements, various legal aspects, and some practical considerations With respect to the technical realization.

WiFi roaming with direct access

The below figure depicts possible steps for the WiFi roaming process in the case of

direct Internet access. The mobile device Md i,k approaches the guest network

Nw j and connects to one of its access points AP. Then, a global access

request is sent to N j which can decide to accept or refuse it. This decision

can be based on either a local authentication decision (steps 2 and 3 are

void in this case) or a delegated one. For the delegated one, N j contacts AA

to authenticate the mobile home network N i (step 2). If needed, N i can be

requested to assert that the mobile user does really belong to it (step 3).

We stress that the actual admission protocol may consist of several

packet exchanges with intermediate local computations. It could also be

possible that during step 2 AA exchanges data with the home network N i

in order to supply directly full authentication information to N j .

M i,k is allowed to access the whole Internet if, at the end of the admission

phase, N j authorizes M i,k to use its own connection. Every subsequent

message of M i,k to the Internet and every response will be forwarded by N j

accordingly (steps 4 and 5).

It is worth to notice that any host on the Internet sees M i,k as a host of N j .

Figure 1. WiFi Roaming with Direct Access

Existing solutions

The only recently proposed approach addressing the citywide WiFi roaming 1 does not rely on a pre-established federation of networks. The guest network N j accepts just any device without authenticating it and grants it a tunneled access to its home network N i using VPN and NAT traversal techniques with the assistance of the STUN server that resolves current IP bindings. Thus, the guest network acts purely as a mediator of the communication mitigating the authentication task to the home network, which itself can be malicious. The authors propose to cut-off the connection if the home network does not respond within a certain time interval. This approach bears various legal risks resulting from the misuse of the

granted connection since the guest network does not receive any information which would be useful to protect it from the legal claims that may arise later. We stress that in WiFi roaming some mechanism allowing the guest network to authenticate mobile devices and to prove to the third parties in the case of dispute that the home network was accessed by that

device is indispensable from the legal point of view. Nevertheless, the tunnelling approach if refi ned by the necessary authentication mechanisms and some contractual agreement between the networks seems to be the most suitable form of WiFi roaming from the security point of view since the connection is granted to one particular address (that is of N i ) and not

to the whole Internet.


There exist several initiatives that suggest solutions for WiFi roaming with direct Internet access. These solutions can be classified in two main categories:

Roaming with local authentication (step 2 in Fig. 1 is void in this case) and roaming with delegated authentication. We will not consider a connection to open WiFi networks as a roaming situation.

Roaming with 'local authentication'

Local authentication is the most spread and simplest way to implement WiFi roaming, for instance this type of authentication is frequently used in WiFi networks

offered by the hotels as well as for other public hotspots, e.g. in the airports. Local authentication can be either offline (e.g. with username/password as in many hotels) or online (e.g. using credit cards or similar payment methods).

Roaming with 'delegated authentication'

There exist several solutions which deploy the concept of delegated authentication. For instance, Fon2 runs on a commercial basis selling own WiFi routers that mediate the authentication of mobile devices wishing to obtain connectivity from a WiFi network to a FON server. FON routers split the WiFi signal creating a secure private channel to broadband internet and a separate channel to be shared with the other users. However, Fon has several security threats44 - in particular the deployed address filter technique allows impersonation attacks by spoofing the corresponding addresses. Wisher45, another commercial WiFi roaming provider, requires guest networks to distribute WEP/WPA keys to authorized guests. Obviously, this is an even riskier approach than Fon since it requires strong trust relationship

that guests do not redistribute the obtained keys. There are several solutions developed for the WiFi roaming in national research and education networks in Europe by the TERENA Task Force on Mobility.46 The most promising of the proposed solutions is eduroam3 based on 802.1X authentication and RADIUS-server hierarchy. It deploys the federated approach where networks become members of a federation through some initial (possibly off-line) contractual agreement. Although member networks share some level of trust, they retain their own administrative control. In eduroam the initial account of a mobile device is created

at its home network, and whenever this device wishes to connect to another network its credentials are routed to the responsible RADIUS-server of the home network which replies with the authentication result. Unfortunately, this service is only offered in research and education networks.