a) In the context of wireless adapters adapters
What are the three types of drivers available for wireless client adapters? State their name and explain their operation
The firmware contained in the Flash memory of the client adapter controls the radio
provides an interface between a computer running a Windows operating system and the client adapter
3.
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Two client utilities are available for use with Cisco Aironet client adapters. They are the Aironet Client Utility (ACU) and the Aironet Client Monitor (ACM). These utilities are optional applications that interact with the radio firmware to adjust client adapter settings and display information about the adapter
2- In the context of the CISCO 3 layer hierarch design please explain the concept of modularity and how it is applied to WLAN design.
in network design allows the user to create design elements that can be replicated as the network grows. When a network design element requires a change, the cost and complexity of making the upgrade is constrained to a small subset of the overall network. In large flat or meshed network architectures, changes tend to impact a large number of systems. Modular structuring of the network into small, easy-to-understand elements also simplifies fault isolation. The user can easily understand the transition points in the network, and thus identify failure points.
3- In the context of Roaming State and explain the five steps to ensure seamless roaming?
The following five steps to ensure seamless roaming: 1) The client sends out a request for association and immediately receives a response from all access points within its coverage area. 2) The client decides which access point to associate with based on signal quality, strength, the number of users associated, and the required number of hops to reach the backbone. 3) After an association is established, the client's Media Access Control (MAC) address drops into the table of the selected access point. If the client encounters difficulty, it will roam for another access point. If no other access point is available, the client will lower its data transmission rate and try to maintain connection. 4) After the client roams to another access point, its MAC address drops into the table of the new access point, which sends a broadcast message basically stating that it received "MAC address X". 5) The original access point forwards any data it had for the client to the other access point, which responds by sending the same to the client.
Security ch8
1.
Unstructured threats - Unstructured threats consist of inexperienced individuals using hacking tools. such as shell scripts and password crackers.
2.
Structured threats - Structured threats come from hackers. who are more highly motivated and technically competent. These people know wireless system vulnerabilities, and they can understand and develop exploit-code, scripts, and programs.
3.
External threats - External threats are organizations working from outside of the company. They do not have authorized access to the wireless network. They work their way into a network mainly from outside the building such as parking lots, adjacent buildings or common areas . These are the type of threats that people spend the most time and money protecting against.
4.
Internal threats - Internal threats occur when someone has authorized access to the network with either an account on a server or physical access to the wire.
Wireless attack methods can be broken up into three categories: 1.
Reconnaissance - Reconnaissance is the unauthorized discovery and mapping of systems, services, or vulnerabilities. It is also known as information gathering and it usually precedes an actual access or DoS attack.
2. Access attack - is the ability for an unauthorized intruder to gain access to a device for which the intruder does not have an account or password 3.
Denial of Service (DoS) - DoS is when an attacker disables or corrupts wireless networks, systems, or services, with the intent of denying the service to authorized users. DoS attacks take many forms. In most cases, performing the attack simply involves running a hack, script, or tool
The IEEE 802.11 standard includes WEP to protect authorized users of a WLAN from casual eavesdropping. The IEEE 802.11 WEP standard specified a 40-bit key, so that WEP could be exported and used worldwide, as indicated
. Most vendors have extended WEP to 128 bits or more. When using WEP, both the wireless client
and the access point must have a matching WEP key. WEP is based upon an existing and familiar encryption type, Rivest Cipher 4 (RC4).
Different authentication types are supported when using 802.1x on a WLAN
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– Lightweight EAP (LEAP) is also called EAP-Cisco. LEAP is the Cisco version of EAP. It is used on networks that currently do not support EAP. The current versions of EAP may not provide the functionality that is needed or may be too demanding. This could compromise the performance of the WLAN equipment. LEAP is a good choice when using Cisco equipment in conjunction with operating systems like Windows 95, Windows 98, Windows Me, Windows CE, Windows NT/2000/XP, and Linux.
– EAP-Transport Layer Security (EAP-TLS) is a labor-intensive security option. EAP-TLS requires a digital certificate configured on all WLAN Clients and on the Server. EAP-TLS is based on X.509 certificates. It is usually easier to use than PEAP, which is based on EAP-TLS.
– Protected EAP (PEAP) is a draft EAP authentication type that is designed to allow hybrid authentication. PEAP employs server-side PKI authentication. For client-side authentication, PEAP can use any other EAP authentication type. Because PEAP establishes a secure tunnel via server-side authentication, non-mutually authenticating EAP types can be used for client-side authentication. Clientside authentication options include EAP-GTC for one-time passwords and EAP-MD5 for passwordbased authentication.
– Extensible Authentication Protocol MD5 (EAP-MD5) should not be used, because it does not provide mutual authentication. EAP-MD5 is a one-way authentication that essentially duplicates CHAP password protection on a WLAN. EAP-MD5 is used as a building block in EAP-TTLS.
– EAP-One Time Passwords (EAP-OTP) is also called EAP- Generic Token Card (EAPGTC). It is not recommended, since OTPs are not a form of mutual authentication.
– EAP-SIM uses the same smart card or SIM that is used in GSM mobile phones to provide authentication. EAP-SIM can easily ride on EAP-TLS.
– EAP-Tunneled Transport Layer Security (EAP-TTLS) is an IETF draft authored by Funk software and Certicom. EAP-TTLS provides similar functionality to PEAP. EAP-TTLS protects passwords by using TLS, which is an advanced form of Secure Socket Layer (SSL). EAP-TTLS currently requires a Funk software RADIUS server.
– Kerberos is not part of the 802.1x standard, but it is being recommended by some vendors. Kerberos is an authentication system enabling protected communication over an open network, which uses a unique key called a ticket. It requires service configuration. PEAP can support Kerberos through EAP-Generic Security Service (EAP-GSS).
An antenna: gives the wireless system three fundamental properties. They are gain, direction, and polarization. Gain is a measure of increase in power. Direction is the shape of the transmission pattern.
The antennas used for WLANs have two functions:
1.
This is the sink or terminator of a signal on a transmission medium. I n communications, it is a device that receives Information, control, or other signals from a source.
2.
This is the source or generator of a signal on a transmission medium.
of an antenna is the band of frequencies, over which it is considered to perform
acceptably. The wider the range of frequencies a band encompasses, the wider the bandwidth of the antenna
is a measurement used to describe directional antennas. Beamwidth is sometimes called half-power beamwidth. It is the total width in degrees of the main radiation lobe, at the angle where the radiated power has fallen below that on the centreline of the lobe, by 3 dB (half-power)
Polarization is the physical orientation of the element on the antenna that actually emits the RF energy. Polarization is a physical phenomenon of radio signal propagation.
There are two categories, or types, of polarization. They are linear and circular.
antenna types include the following:
1.
– This is a hypothetical antenna that radiates or receives energy equally in all directions. Isotropic antennas do not exist physically, but they represent convenient reference antennas for expressing directional properties of physical antennas
2.
3.
– This is usually a straight, center-fed, one-half wavelength antenna. – This is an assembly of anten na elements with dimensions, spacing, and illumination sequence arranged in such a way that the fields for the individual elements combine. This combination produces a maximum intensity in a particular direction and minimum field intensities in other directions.
Diversity is the simultaneous operation of two or more systems or parts of a system. Diversity is used to improve system reliability. Multipath fading can cause temporary failures in even the best-designed paths. Diversity is a possible solution to this problem. Two types of diversity are as follows: 1.
Space Diversity
2.
Frequency Diversity
there are six options for configuring the root state and related parameters on the BR350. These options correspond to the following six roles, which a bridge can assume in a LAN:
Root bridge
Non-root bridge with clients
Non-root bridge without clients
Root access point
Repeater access point
Site survey client
Ethernet port :
This section describes how to configure the bridge Ethernet port, using the Ethernet pages in the management system. The Ethernet pages include the following 1.
Contains the basic locating and identity information for the Ethernet port.
2.
Contains the setting for the Ethernet port connection speed of the bridge.
3.
Contains settings for the operational status of the bridge Ethernet port.
ACCESS POINT 5:
There are three basic models of Cisco APs 1- 1200 2-1100 3-350
IOS and VxWorks are the two different operating systems available on Cisco Aironet APs and bridges
An access point can be controlled and configured though command line and Web interfaces. Management can
also be done through traditional protocols like SNMP. A variety of antenna options can provide additional reach or speed, depending on the installation. An access point can be single band, like an 1100 AP
There are two basic GUI interfaces .
IOS
VxWorks
The 350 series AP and Bridge currently use the VxWorks interface. The 1100 only uses the IOS image. The 1200 Series is capable of either, however a IOS AP should not be downgraded to VxWorks. Any AP that is running the IOS image also contains the IOS CLI code common to Cisco routers and switches. This makes an easy transition for existing Cisco network administrators.
The AP will get an IP address using DHCP, if possible. If no DHCP server is available, a Cisco AP will use the static IP address 10.0.0.1, by default.
This feature enables Web-based GUI management by providing support for HTML Web pages and Common Gateway Interface (CGI) scripts using common Web browsers
The help files can be pointed to one of three possible locations:
– Cisco maintains up-to-date help for devices on the Cisco website. While this location requires online access for every occasion of needing online help, it offers the most up-to-date information.
– On multi-user networks, the help files can be placed on the network file server.
– The help files can be copied to the hard drive of the computer which is used to manage the wireless LAN.
