Wireless LAN security

1. Introduction

When wireless LANs are widely deployed and we know a lot about its benefits, it is also very difficult to go with it. This article only mentioned and discussed some basic techniques for securing this system and some effective security solutions.

2. Why security is so important

Why should we care about the security of wireless LAN? This stems from the inherent nature of the wireless environment. To connect to a wired LAN you need to access the cable connection, connect a PC to a network port. With wireless networks you only need to have your device in the coverage area of ​​the wireless network. Control for wired networks is simple: common cable connections are in high-rise buildings and unused ports can make it disabled by management applications. Wireless networks (or wireless) use radio waves through building materials and thus coverage is not limited to inside a building. Radio waves can appear on the street, from stations that broadcast from these LANs, and as someone can access them with the appropriate device. Therefore a company's wireless network can also be accessed from outside its corporate building. Figure 1 shows how a stranger can access a wireless LAN from outside. The solution here is to get security for this network to resist this type of access.

Example of a stranger accessing the network

3. Weaknesses in security 802.11

The IEEE 802.11 standard offers a WEP ( Wired Equivalent Privacy ) to protect wireless transmissions. WEP is using a symmetric zero string to encrypt users in the wireless network. 802.11 offers 64-bit WEP keys but is provided with a 128-bit WEP key. 802.11 does not show how the keys are arranged. A WEP consists of two parts: a 24-bit initialization (IV) vector and a secret key. IV is played in plain text in the header of 802.11 packets. However it is very vulnerable to 'crack'. So the next solution is to use dynamic WEP keys that can be changed on a regular basis.

The 802.11 standard identifies clients using WEP keys. The industry standard was then introduced through 802.1x validation (see section 7 ) to complement the shortcomings of the previous 802.11 standard. Recently, however, the University of Maryland has documented the problem of potential security issues with this 802.1x protocol. The solution today is to use mutual validation to prevent 'someone in between' attacks and dynamic WEP keys, which are carefully arranged and encrypted channels. Both of these techniques are supported by the protocol ( TLS: Transport Layer Security ). Most prominent is the per-packet locking and checking the integrity of the message. This is the 802.11i security standard.

See more: Wireless LAN security (Term 2)
Wireless LAN security (Term 3)

Pham Van Linh
Email: vanlinh@quantrimang.com