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UNIVERSIDADE FEDERAL DE SÃO JOÃO DEL-REI – Campus Alto Paraopeba 
 
ENGENHARIA DE TELECOMUNICAÇÕES 
 
 
 
 
 
 
Resumo sobre segurança de redes Wi-Fi 802.11 
 
 
 
 
 
 
 
 
 
NOME: Davi Silva Sousa 
MATRÍCULA: 154 350 001 
 
 
 
 
 
 
 
 
 
 
 
26 de setembro de 2017 
Ouro Branco- MG 
 
 
 
 
A wireless network is the way that a computer is connected to a router without a 
physical link. In another words, it uses radio frequency to transmit data through the air 
which brings to us more mobility but we must be careful. Hackers may invade our 
personal computer and steal private data among far worse things. 
That’s why we have got security algorithms like WEP - Wired Equivalent Privacy, its 
intention was to provide data confidentiality but it has serious security flaws and was 
replaced by WAP - Wi-Fi Protected Access. Currently we've got the WPA Version 2. 
Several weaknesses have been discovered using WEP encryption that allows an 
attacker using readily available software to crack the key within minutes. WEP 
encryption uses a shared key authentication and sends the same key with data packets 
being transmitted across the wireless network. If malicious users have enough time and 
gather enough data they can eventually piece together their own key. 
 
The Wi-Fi was created by Wi-Fi Alliance, a non-profit organization that 
promotes Wi-Fi technology and certifies Wi-Fi products if they conform to certain 
standards of interoperability. 
Down below we have got the main standards in the IEEE (Institute of Electrical 
and Electronics Engineers) 802.11 family listed. 
 
• IEEE 802.11a 
 
A Wi-Fi standard for 5 GHz frequency which is less crowded and hence has relatively 
smaller interference problem, beyond that supports up to 54Mbps of bandwidth, which is 
much faster than the 11Mbps bandwidth provided by 802.11b standard devices. The 
802.11a offers as many as 12 non-overlapping channels. With more channels, larger 
number of users can be accommodated with no performance degradation. Although it has 
some disadvantages like not many client devices such as note book computers, PDAs 
support 802.11a standard, it is more expensive compared to other contemporary 
technologies like 802.11b and Bluetooth and the distance covered will be slightly less 
compared to 802.11b due to higher operating frequency (5 GHz). Note that, higher the 
radio frequency, lower the propagation distance for a given output power. 
• IEEE 802.11b 
When compared to the IEEE 802.11a protocol presents a better cost effective, it is 
well-supported and stable but runs in the 2.4 GHz range that makes it prone to 
interference from other devices (microwave ovens, cordless phones, etc) and also has 
security disadvantages. This protocol limits the number of access points in range of 
each other to three. Has 11 channels, with 3 non-overlapping, and supports rates from 1 
to 11 Mbps, but realistically about 4-5 Mbps max. Uses direct-sequence spread-
spectrum technology. 
• IEEE 802.11g: Wi-Fi standard for 2.4 GHz frequency with theoretical capacity 
of 54 Mbps. When compared to IEEE 802.11 
Has the same extension of 802.11b, with the same disadvantages (security and 
interference) furthermore, it has a shorter range than 802.11b. We can also say that this 
protocol is flexible because multiple channels can be combined for faster throughput, 
but limited to one access point and it is and has a higher cost than 802.11b. 
• IEEE 802.11n : Wi-Fi standard for 2.4 GHz and / or 5 GHz frequency with a 
capacity of 150 to 600 Mbps. This pattern uses the MIMO-OFDM transmission 
method. 
The 802.11n protocol is faster and less prone to interference and it uses the newest 
security. 
There are other protocols like EAP - Extensible Authentication Protocol and 
VPN – Virtual Private Network. VPN creates a secure virtual “tunnel” from remote 
device to VPN server using an encryption scheme and require authentication. The EAP 
has several versions available and is used in internal network beyond that, it has an 
extra security for enterprise and government Wi-Fi LANs. 
To ensure more safety we might use Network Security Systems las such 
Firewall. The first one acts as a barrier between a trusted network and and an untrusted 
network; only traffic allowed onto the network is defined in the firewall policy; all other 
traffic is denied. It could make the network or computer invisible to the internet. Block 
unauthorized users. Monitor and control flow of data to/from a network or computer. 
Many devices provide basic firewall capability. The Second one is a computer 
network authentication protocol created at MIT that works on the basis of tickets to 
allow nodes communicating over a non-secure network to prove their identity to one 
another in a secure manner. 
As shown above the Wi-Fi has its risks and can be slower than cable besides 
that, it has advantages like freedom, setup cost, flexibility and Scaleable. Any 
combination of these security techniques can be used. A good way defend yourself 
when using WEP would be to use longer WEP encryption keys, change your WEP keys 
frequently, to use a VPN for any protocol, including WEP, that may include sensitive 
information and lastly implement a different technique for encrypting traffic, such as 
IPSec over wireless. 
 
REFERENCES 
NETWORKING, Disponível em: 
http://networking.anandsoft.com/802.11a.html 
Accessed at 05:47 on 09/26/2017 
 
http://searchsecurity.techtarget.com/ 
Accessed at 6amàs 06:54 on 09/26/2017 
 
SLIDES :Wi-Fi the 802.11 Standard and Security 
WiFi Security: WEP, WPA, and WPA2 
Attack and Defense in Wireless Networks 
 
 
	26 de setembro de 2017