The diffused infrared configuration however, uses a transmitter that fills a given office space with signals. The signal receiver can then be located anywhere in the office area in order to successfully receive the IR signal.
The Spread spectrum LANs
This form of arrangement utilizes the multiple-cell configuration. Each of the cells are appropriately assigned a unique center frequency that lies within a specific band in order to avoid signal interference. This transmission technique makes use of two methods; frequency hopping as well as direct sequence modulation
The Frequency hopping method uses signals that jumps from a given frequency to the other within a specific bandwidth. The transmission unit then "listens" to a give channel and if successfully detects any idle time (a time when no signal is transmitted),then transmits the packet via the full channel bandwidth .In case a channel is deemed "full," the transmitter then "hops" to the next channel and then the process is repeated. Both the transmitter and the receiver have the same "jumping" behavior.
In the case of Direct Sequence Modulation, a wide frequency band as well as Code Division Multiple Access (CDMA) is utilized. The signals from various units (multiple) are then transmitted at a certain range of frequencies at relatively lower power. With each signal transmitted, there is a code to be used by the receiver in the identification of the appropriate signal from the sending unit. This frequency falls within the industrial, scientific and medical (ISM) band.
The Narrow and Microwave Local Area Networks (LANs)
This type of LAN is implemented using narrow bandwidth microwaves frequencies in the transmission of signals. Most of the equipment using this bandwidth range needs licensing from FCC. They employ 18.82-19.205GHz of frequency spectrum (radio).
The Licensed narrow radio frequencies which involves the use of narrowband frequency schemes that employ cell configuration whereby the cells that are adjacent employ nonoverlapping bandwidths that lie within the 18 Ghz band. An advantage of this scheme is that it allows foir a guaranteed communication that has no form of interference. The communication channels are also highly encrypted in order to eliminate threats of unauthorized data interception (eavesdropping).
The unlicensed Narrow RF also operates within the ISM spectrum and can be employed for transmissions of power less than 0.5 watts.
A comparison of the techniques of Wireless transmission
Source: Burrell (2002)
The Wireless LAN Topologies
The WLAN makes use of three main topologies;
1. Basic Service Set (BSS)
2. Independent Basic Service Set (IBSS)
3. Extended Service Set (ESS)
A further classification involves two modes. Namely, the ad hoc and infrastructure modes.
Wireless topologies. Source- Burell (2002).
WLAN Security threats and vulnerabilities
A close examination of the WLAN systems reveals a system that is not entirely safe from threats. The WLAN attacks are aimed at interfering with the confidentiality, integrity and availability of the system and the data within it. These security attacks can come in the form of active or passive attacks.
The passive attacks;
These attacks are made up of unauthorized data WLA system access for the purpose of either traffic analysis or eavesdropping. It can also be for the purpose of modifying the content of the data traffic and therefore interfering with its integrity. The passive network attacks are hard to detect as the data is often unaffected. This therefore calls for prevetion efforts such as encryption other than detection.
These forms of network attacks involves the unauthorized access of WLAN resources for the purpose of malicious data modification or the interruption of the given network service (Jeopardizing the availability of the system).
Classification of WLAN attacks
Source: Sunday (2008).
The security risks include;
1. WLAN Network Detection
3. Radio Frequency Signal Limiting
5. Data Interception
6. Denial of Service
7. Compromised Devices
8. Illegal Access Point deployment
9. Insider Threat
10. Unauthorized Network Access.
Wireless LAN security risks and mitigation techniques
Table 2: Wireless VoIP Risk Assessment and mitigation
Overview of VoIP
1. VoIP has the similar security threats like any other IP data networks as well as other new ones
2. The traditional information technology security products are never equipped with the right systems to address the challenges that face the security framework of voice systems.
Materna (2009) points out the following as current status of VoIP.
1. VoIP is different from the traditional data security systems
2. VoIP is a real-time system
3. VoIP is a mission-critical service
4. VoIP is faced with malicious activities that are voice specific
5. VoIP presents a new front of cyber attacks
On the Application side
On the side of the devices
On the part of the protocols
The VoIP technology is still in its early stages of deployment. This therefore means that there are few recorded incidents as well as more unpublished ones.
A typical PBX deployment. Source-Materna (2009)
A typical IP Vice center
In a VoIP system confidential data is collected, stored and also transmitted via the VoIP infrastructure. There are serious breaches caused by the complex flow of calls and the infrastructure. Outsourcing increases this risk.
The security threats
In a VoIP system there are several vulnerabilities and exploits caused by the complex permutation and numerous attack vectors as shown below. This is illustrated by Materna (2009) in the diagram below.
Source: Materna (2009)
For the wireless LAN, mitigation should be put in place as shown in table 2. Organizations must also proactively prevent the risks by installing firewalls and intrusion detection systems. An elaborate security policy must also be adopted and adhered too in all organization that deploy WLAN for their operations. As for the VoIP there should be;
Through, assessment of compliance to security policies, vulnerability and risk assessment as well as patching.
Using a perimeter such as Firewall, SPIT, IPS and Internal protection using NAC, HIPS and Encryption. People should also be educated in order to increase their awareness of the risks associated with the VoIP security vulnerabilities. It is appropriate to outsource the hosting of the tracking servers due to the high cost and risk involved. This is also due to the fact that the operation of the server is mission critical.
Cybertrans should upgrade its services in order to meet the current industry stands of compliance. A risk assessment is necessary in order to ensure that the systems are operational 24 hours a day.
Bruce, WR (2002).Wireless LANs End to End, Ron Gilster (ed.), John Wiley & Sons.
Burell, J (2002) 'Wireless Local Area Networking: Security Assessment and Countermeasures: IEEE 802.11 Wireless Networks', Dec. 2002, retrieved 22 March
So as to receive the infrared signals, the receivers can be placed at any location within the office space.
The spread spectrum WLANs
This system makes use of multiple-cell configuration. This is to say that each of the cells in the arrangement is assigned a certain center frequency that is unique and that lies within a chosen band as to eliminate chances of signal interference. The system employs frequency hopping and