IT 376 Exam 1 Review (HW1 & HW2)
Performance increasing techniques in wireless networks are Equalization, multisubcarrier modulation, and ____________________
power control
Base Station Controller (BSC) provides: a. radio connection between mobile users and the switch b. Compresses speech signals for more efficient transmission over the radio spectrum c. Implements the handoff of calls from one base station to another as users drive across the system d. All of the above e. b&c
Answer: E
HLR (Home Location Register) is the official database of all customers of wireless systems. Customers Information include: a. current account status/validity b. phone's technical parameters c. whether the phone is presently turned on d. Secret keys for authentication to avoid fraudulent use/cloning e. All of the above
Answer: E
TKIP advantages over WEP are (is): a. TKIP uses a longer 128-bit key b. TKIP uses a new key for each packet c. Extension of IV to 48 bits instead of 24 d. Adds a frame integrity-check function (It is called Message Integrity Check (MIC) e. All of the above
Answer: E
The presence of reflectors, edges, or trees in the environment surrounding a transmitter and receiver a. Create multiple paths b. Receiver sees the superposition of multiple copies. c. Each signal copy will experience differences in attenuation, delay and phase shift. d. Will result in either constructive or destructive interference e. All of the above
Answer: E
The switch is also responsible for: a. storing billing records b. Interpreting dialed phone numbers c. routing calls d. Implementing all calling features e. All of the above
Answer: E
Provide Type and Key Size for these algorithms: DES TripleDES Blowfish AES RC4
DES - Block Cipher - 56 bits TripleDES - Block Cipher - 168 bits Blowfish - Block Cipher - Up to 448 bits AES - Block Cipher - 128, 192, or 256 bits RC4 - Stream Cipher - 40 or 128 bits
The second generation GSM technology was Developed in Europe which used FDMA as an access technology with a channel bandwidth of 200KHz and accommodate up to 8 users with reuse equal to 4.
True
Thin Access Point is an access point without the authentication and encryption functions.
True
To connect, a computer needs the SSID (network name), which is send out by the router as beacon frames announcing the SSID.
True
Wireless VLANs can segment traffic and increase security in same or different switches.
True
Wireless communication transmitting voice and data using electromagnetic waves in open space (atmosphere)
True
Base Station (BTS) provides: a. radio connection between mobile users and the switch b. Compresses speech signals for more efficient transmission over the radio spectrum c. Implements the handoff of calls from one base station to another as users drive across the system d. All of the above e. b&c
Answer: A
The following are examples of Basic Security Services except: a. Data Confidentiality b. Data Integrity c. Encryption d. Non-Repudiation
Answer: C
A well-known CIA security model include ____________________ , ____________________ , and ____________________
Confidentiality, Integrity, Availability
____________________ is a solution to combat Dispersion phenomena (ISI).
Equalization
Cryptology is the science (art) of encryption.
False
The PSK is used in WPA as an encryption key.
False
____________________ adequately approximates BER in wireless.
Markov Chain
WPA design goal to address both wireless authentication and encryption using ____________________ for authentication and ____________________ for encryption.
PSK, TKIP
AES is an example of ____________________ cipher and RC4 is an example of ____________________ cipher.
Symmertic Block, Stream
802.11i - Authentication and encryption protocols.
True
Auditors use wireless protocol analyzer for sniffing rogue access points and for more security, they set up wireless probes to monitor the RF frequency for any threat
True
Bandwidth of a signal is the width of the frequency spectrum which refers to the range of component frequencies.
True
Effective path loss (LsF) increases at higher frequencies (LsF is proportional to fc2 ) due to increase absorption and attenuation at higher frequency.
True
Generally, in wireless infrastructure we use Pico cell in building, Micro cell in urban, and Macro cell in suburban.
True
In CDMA technology we use Eb/No instead of C/I in which Eb represents the signal energy per bit and No represents noise power density per Hertz. Eb/No typically = +6 dB.
True
In October 2003, Wi-Fi (Wireless Fidelity) Alliance introduced Wi-Fi Protected Access (WPA)to protect both present and future wireless devices, addresses both wireless authentication and encryption
True
Intrusion Detection and Prevention Systems is an example of basic security services.
True
MAC addresses filtering is very weak because MAC addresses are transmitted in the clear text and an attacker can just sniff for MACs
True
Preshared key (PSK) authentication uses a Passphrase to generate the encryption key, which must be entered into both the access point and all wireless devices (Prior to the devices communicating with the AP).
True
Strong destructive interference to the signal is referred to as a slow fade and may result in temporary failure of communication due to a severe drop in the channel signal-to-noise ratio.
True
TKIP consider as a short-term solution for WLAN security, which is used to ease the transition from current WEP WLAN to the next RSN networks.
True
There are two types antenna isotropic and dipole, the dipole has 2.15 dB gain compared to isotropic antenna.
True
Markov model comprise two states ____________________ and ____________________ states.
transient, recurrent
Compare different multiple access technologies FDAM, TDMA, and CDMA
§ FDMA (Frequency Division Multiple Access) FDMA divides frequencies into sub channels like FM radio. The drawback to this method is that as you add more and more sub channels, there will be a lot of interference with other nearby channels. § TDMA (Time Division Multiple Access) TDMA divides the main channel by time slots instead of sub channels. This is an organized use of one channel by multiple users simply spread by time. There is a maximum number of time slots as they would begin to overlap. § CDMA (Code Division Multiple Access) CDMA does not divide its channel but assigns codes to them, using these codes to separate conversations. The more people use this method though, the more noise generated. Also, if a signal is much stronger than others it could mask them, causing them to not be heard.
Each AP can be programmed with the set of MAC addresses and each client identified by its MAC Address to be permitted to access AP
True
Electromagnetic Waves travel at speed of light and has a frequency and wavelength. The Higher frequency means higher energy photons, and the higher the energy photon the more penetrating is the radiation
True
Give an example or method on how to attack each of the security Model CIA: Confidentiality: Integrity: Availability:
Confidentiality: A method of attacking Confidentiality could be a phishing attack. When the victim uses the false login, the attacker would gain access to data they are not supposed to see. This is a confidentiality breach. Integrity: A method of attacking Integrity could use the Confidentiality attack then, using admin powers, change the data you have access to. This would mean the data in the server can not be verified as changes were made by a supposed administrator. Availability: A method of attacking Availability would be a DDOS attack. Overwhelming the server would cause availability issues as servers scramble to complete too many requests.
Channel refers to the elements within that range.
False - Frequency Standard
Antenna Gain is ABSOLUTE not RELATIVE, the gain in one direction comes at the expense of less radiation in other directions.
False - Its Relative
AMPS used one single powerful transmitter/receiver (base station) provided coverage of up to 50km based on FM technology, each voice channel of 3kHz used 120KHz of spectrum, and only half duplex service was available.
False - MTS
In FDMA, each user has a private time on a private frequency, but it only belongs to the user during certain time slots in a repeating sequence
False - TDMA
TDMA operates by using a new dimension, CODING, to discriminate between users.
False: CDMA
NTIA allocates radiofrequencies to countries for international use.
False: ITU
Radio waves (Electromagnetic Waves) are generated by an antenna and they propagate in all directions as a straight line
True
Real-life wireless propagation signal decay rates are typically somewhere between 30 and 40 dB per decade of distance compared to 20 dB in ideal free space
True
TLS is the successor of SSL and provides encryption, authentication, and integrity for web communications.
True
Briefly compare the following multipath effects of : slow fading, fast fading
Answer: Slow Fading (shadowing Fading): Slow fading causes signal to degrade, reducing SNR and slowing. This is usually caused by large buildings or other major obstacles. Fast Fading (Rayleigh Fading): Fast fading causes distortions in the shape of the signal and creates ISI. Usually caused by movement of transmitter or receiver and reflections off surfaces.
802.1X is a port-based authentication involves three parties. Mention them and explain each of one?
Answer: 802.1's three parties include the Supplicant, an Authenticator, and the Authentication Server. The supplicant is the end user's device. Phones, laptops, printers, and smart watches as well as any device that requests authentication. The Authenticator is the door to the network. It initiates the connection, establishes a link and then manages connectivity. The Authentication server is central to security management. It processes requests and accepts or denies requests depending on the policies set up.
Symmetric key cryptography includes: a. Single key shared between communicating parties b. Secret key will never be shared with anyone else c. public key can be shared freely d. message encrypted with secret key can only be decrypted with corresponding public key e. Computationally expensive f. All the above except a
Answer: A
What do mean by Security is about protection of assets using PDR (Prevention, Detection, Reaction)?
Answer: Assets are secured by PDR really well as it covers three states of security, Prevention, Detection and Reaction. Prevention is the protection of data, physically and electronically through locks and firewalls. Detection are the methods that detect attacks or damage to assets; examples of this are physical alarms and records of changes to assets. Reaction relates to the recovery of assets through insurance or rebuilding using other data. When combined, these three pillars provide a good defense as well as a plan for recovery.
The Carrier to Interference (C/I) threshold in GSM technology is: a. +17 dB b. +14 to +17 dB c. +7 to 9 dB d. -10 to -17 dB
Answer: C
all the following are cryptographic Security Mechanisms examples except: a. Message Digest b. Digital Signatures and Message Authentication Codes (MAC) c. Notarization d. Non-Repudiation e. Timestamping
Answer: C
802.11b security to Secure Access Point (AP) Access includes: a. Service Set Identifier - SSID b. Media Access Control (MAC) Address Filtering c. Wired Equivalent Privacy - WEP d. all the above
Answer: D
All the following are Hash Examples except: a. MD2, MD4, MD5 - 128 bits b. SHA-256, 384, 512 bits c. Whirlpool - 512 bits d. SAH-160 e. Tiger - 192 bits
Answer: D
An attack surface consists of the reachable and exploitable vulnerabilities in a system and the following are examples of surface attack except: a. Open ports on outward facing Web and other servers, and code listening on those ports b. Services available in a firewall c. Code that processes incoming data, email, XML, office documents, etc. d. An employee with access to sensitive information vulnerable to a social engineering attack e. Limited CPU and RAM in network's hardware
Answer: D
Carrier to Interference (C/I) in wireless system determine: a. The margin that is stronger than all interference in desired signal b. The amount of interference can be tolerated as threshold = C/I. c. That co-channel users don't have interference worse than C/I. d. All of the above e. b&c
Answer: D
Categories of cryptographic algorithms include all the following except: a. Symmetric key algorithms b. Public key algorithms c. Elliptic curve algorithms d. Random Number Generation algorithms e. Hash
Answer: D
Encryption Modes include All the following except: a. ECB - Electronic Code Book b. CBC - Cipher Block Chaining c. OFB - Output Feedback d. IFB - Input Feedback e. CTR - Counter
Answer: D
Higher signal frequency causes: a. Increase path loss b. Higher Doppler Shift c. Increase mobility problems d. All of the above e. a&b
Answer: D
RC4 PRNG is a: a. Symmetric Algorithm b. 40 bit encryption key + 24 bit initialization vector à64 bit seed c. 64 bit string is used as seed to PRNG to generate a "key sequence" d. all of the above e. a&c
Answer: D
The wavelength of a radio signal determines many of its propagation characteristics: a. Antenna elements size are typically in the order of 1/4 to 1/2 wavelength b. Objects bigger than a wavelength can reflect or obstruct RF energy c. RF energy can penetrate into a building or vehicle if they have apertures in size, or larger than the wavelength d. All of the above e. b&c
Answer: D
WLAN Security Exploits attacks include: a. Brute Force Attacks against AP Passwords b. Client-to-client Attacks such as DoS - duplicate MAC or IP addresses c. Encryption Attacks d. all the above e. a & c
Answer: D
The way Radio System transmit the information wirelessly is : An antenna is just a passive a. Information transmitted to antenna as RF signal causes the current flow in antenna transmitter. b. antenna transmitter converts the RF signal into an electromagnetic wave which travel through free space to the receiving antenna. c. The electromagnetic wave is intercepted by the receiving antenna which converts it back to an RF signal where the original information is then demodulated back to its original form. d. All of the above e. A&b
Answer: E
Types of Wireless Probes is (are): a. Wireless device probe. b. Desktop probe c. Access point probe d. Dedicated probe e. all the above
Answer: E
WPA2- AES-CCMP Encryption enhancement over WPA are (is): a. IV size is 148 bits. b. Uses stronger encryption of AES-CTR with 128-bit key and 128-bit block size to generate ciphertext payload. c. Cipher Block Chaining Message Authentication Code (CBC-MAC) for integrity. d. all of the above e. b &c
Answer: E
You can add more security to WLAN through different means such as: a. firewalls, which isolate wireless traffic from wired network b. intrusion detection to detect attacks on wireless networks c. IPSec / VPNs to protect traffic at IP layer d. TLS (SSL) to protect traffic at application layer e. All of the above
Answer: E
Asymmetric key (public key) cryptography includes: a. Single key shared between communicating parties b. Secret key will never be shared with anyone else c. public key can be shared freely d. message encrypted with secret key can only be decrypted with corresponding public key e. Computationally expensive f. All the above except a
Answer: F
In handoff process: a. Base station informs BSC that it is losing signal with the subscriber. b. BSC will then solicit signal strength values from neighboring cells c. BSC will examine reported signal strength values and chose the cell whose signal strength value exceeds the threshold. d. BSC will check available frequencies in the chosen cell, pick one and pass the information to the cell's base station to trigger handoff. e. The base station will change the transmit and receive frequencies of the subscriber to the new cell. f. All of the above
Answer: F
What is the difference between Isotropic and dipole antenna and which has more gain?
Answer: Isotropic antennas radiates in all directions like a sphere while dipole antenna radiates in a shape resembling the shape of a doughnut. Because of this concentration frC-om the dipole antenna, it has a gain of 2.15dB.
Briefly describe the role of antenna to the signal at the receiver and transmitter sides.
Answer: On the transmitter side, a specific voltage is applied to the antenna which then generates magnetic and electrical waves. On the receiver side an antenna does the opposite, receiving the produced signals converts it to alternating currents which the receiver takes the information from.
Mention two methods to combat the fast (Rayleigh) fading:
Answer: One method is Space Diversity, where two antennas are used to receive the best possible signal. The second method would be tone signaling different digits to different tones.
Extended security components of ssecurity (principles) are called CIAAAN, explain each principal?
Answer: The five components making up CIAAAN are Confidentiality, Integrity, Availability, Authenticity, and Non-Repudiation. Confidentiality is data privacy, making sure that data is only available to those that have clearance. Integrity is data non alteration, making sure that the data itself has not been tampered with and changed. Availability is reliable access to services, assuring that data is available to those with clearance when they need it. Authenticity is like Integrity but focuses on making sure the communication itself is genuine. Authentication. Non-Repudiation focuses on logging data related to the modification of data for the purpose of having proof of ownership or at least obligation
There are three aspects of information security, what are they, briefly explain them?
Answer: The three aspects of information security are Confidentiality, Integrity, and Availability. Confidentiality relates to keeping data confidential and only available to those who are supposed to have access to it. Integrity assures the data has not been tampered with or changed completely. And Availability assures that the data and services needed are online and ready to be used when supposed to
__________ Interruption __________ Interception __________ Deception __________ Fabrication __________ Disclosure __________ Modification a. an unauthorized party (human or not) gains access to an asset b. an asset becomes lost, unavailable, or unusabl c. an unauthorized party changes the state of an asset d. an unauthorized party counterfeits an asset e. an attack on data confidentiality f. providing wrong data by attacking on data integrity
B - Interruption A - Interception F - Deception D - Fabrication E - Disclosure C - Modification a. an unauthorized party (human or not) gains access to an asset b. an asset becomes lost, unavailable, or unusabl c. an unauthorized party changes the state of an asset d. an unauthorized party counterfeits an asset e. an attack on data confidentiality f. providing wrong data by attacking on data integrity
__________ Isotropic Antenna __________ Dipole Antenna __________ Electromagnetic wave __________ Bit Error Rate (BER) __________ Propogation Models __________ Link Budget __________ Space Diversity __________ Multipath Interference __________ Dispersion __________ Higher Frequency __________ Impairment a. Is the carrier of RF signal through the free space. b. Is a measure of Effective Isotropic Radiated Power. c. Is a measure of effective Radiated Power d. causes reception errors and lower bit rate as a result of wave propagation e. increases problems for mobility/Doppler effects f. Is an Inter-symbol interference (ISI) g. the receiver sees the superposition of multiple copies of the transmitted signal, each traversing a different path. h. can be obtained by using two receiving antennas and switching instant-by-instant to whichever is best. I. is a way of quantifying the link performance. J. Is a model to predicts arrival signal to receiver K. is the number of corrupted bit per second.
B - Isotropic Antenna C - Dipole Antenna A - Electromagnetic wave K - Bit Error Rate (BER) J - Propogation Models I - Link Budget H - Space Diversity G -Multipath Interference F - Dispersion E - Higher Frequency D - Impairment a. Is the carrier of RF signal through the free space. b. Is a measure of Effective Isotropic Radiated Power. c. Is a measure of effective Radiated Power d. causes reception errors and lower bit rate as a result of wave propagation e. increases problems for mobility/Doppler effects f. Is an Inter-symbol interference (ISI) g. the receiver sees the superposition of multiple copies of the transmitted signal, each traversing a different path. h. can be obtained by using two receiving antennas and switching instant-by-instant to whichever is best. I. is a way of quantifying the link performance. J. Is a model to predicts arrival signal to receiver K. is the number of corrupted bit per second.
___________ Isaac Newton ___________ S. Morse ___________ A. G. Bell ___________ H. Hertz ___________ N. Stubblenfiend ___________ AT&T Bell Lab ___________ G. Marconi a. patented his telegraph in 1837 b. patented his telephone in 1876 c. shows idea of light split into a spectrum in 1680 d. demonstrates a wireless radio telegraph in 1895 e. gives demo of electromagnetic waves of radio frequencies in 1888 f. demonstrates voice over radio in 1902 g. introduced the cellular concept in 1950s and 1960s
C - Isaac Newton A - S. Morse B - A. G. Bell E - H. Hertz F - N. Stubblenfiend G - AT&T Bell Lab D - G. Marconi a. patented his telegraph in 1837 b. patented his telephone in 1876 c. shows idea of light split into a spectrum in 1680 d. demonstrates a wireless radio telegraph in 1895 e. gives demo of electromagnetic waves of radio frequencies in 1888 f. demonstrates voice over radio in 1902 g. introduced the cellular concept in 1950s and 1960s
__________ Trapdoor __________ Worm __________ Trojan Horse __________ Logic Bomb __________ Bacterium __________ Virus a. -A specialized form of virus which does not attach to a specific file. b. - Malicious [program] logic that activates when specified conditions are met. Usually intended to cause denial of service or otherwise damage system resources. c. - A hidden computer flaw known to an intruder, or a hidden computer mechanism (usually software) installed by an intruder, who can activate the trap door to gain access to the computer without being blocked by security services or mechanisms. d. - A computer program that appears to have a useful function, but also has a hidden and potentially malicious function that evades security mechanisms, sometimes by exploiting legitimate authorizations of a system entity that invokes the program. e. - A hidden, self-replicating section of computer software, usually malicious logic, that propagates by infecting (i.e., inserting a copy of itself into and becoming part of) another program. A virus cannot run by itself; it requires that its host program be run to make the virus active. f. - A computer program that can run independently, can propagate a complete working version of itself onto other hosts on a network, and may consume computer resources destructively.
C - Trapdoor F - Worm D - Trojan Horse B - Logic Bomb A - Bacterium E - Virus
802.11b is a wireless network bearer in 2.4 GHz ISM band with data rates up to 54 Mbps; compatible with 802.11b, 802.11n
False
802.11g is a wireless network bearer operating in the 2.4 and 5 GHz ISM bands with data rates up to 600 Mbps.
False
Authentication is a process of proving that person/device has performed a certain transaction/transmission
False
Data Confidentiality is an example of security mechanisms.
False
Doppler shift in mobile system occurred when receiver and transmitter are moving towards each other, the received frequency is less than the source, while received frequency would be higher than the source when they are moving away from each other.
False
Each AP is programmed with an APID that corresponds to its network then client computer presents correct APID to access AP
False
ICV (integrity check vector) is computed for plaintext (CRC-32) then is appended to plaintext to make data bit string, which is XORéd to Key stream Sequence to create ciphertext.
False
Multipath propagation mechanisms causing reception errors are refraction(R), diversion(D), and scattering(S).
False
TKIP based on RC4 stream cipher algorithm, surrounds WEP cipher engine with 3 new algorithms, 1) Extended 48-bit Initialization Vector (IV), 2) New per-packet key mixing function, re-keying, and 3) A message integrity check (MIC) 'Michael', ensures messages haven't been tampered with during transmission
False
Using PAP, the user sends an authentication identification only username, then the system checks validity of the identification and password and accepts or denies connection
False
The information from sender to receiver is carrier over a well-defined frequency band. This is called frequency spectrum.
False - Channel
____________________ the data stream is divided into N interleaved substreams, which modulate the carrier of each subband.
Multisubcarrier modulation
Given the following path loss formula: Path Loss [dB ]= 32.26 +20*Log10(FMHz)+20Log10(DistMILES ) Let's estimate the feasibility of a give wireless system of a 5 miles (Distance) link, with one access point (AP) as transmitter and one client radio as a receiver. Transmitter: The access point (AP) is connected to an antenna with Gtx =18 dBi gain, with a transmitting power of Ptx = 25 dBm and a receive sensitivity of Rs=-89 dBm. Receiver : The client is connected to an antenna with Grx = 15 dBi gain, with a transmitting power of Prx =20 dBm and a receive sensitivity of Rs = -82 dBm. The cables in both systems are short, with a loss of L = 2dB at each side at the 2.4 GHz frequency of operator, and distance of 5 miles Find in both ways the: 1. Use the above formula of path loss to calculate the path loss in dB. 2. Total gain for both sides 3. The link margin for both sides
Q1: 32.26+20log(2500) + 20log(5) = 114.198dB Q2: Transmitter: -18+25-2+15-2 = 54dB Receiver: -15+18-2+20-2 = 49dB Q3: 54-114.198 = -60.198dBm T: -59.84-(-82) = 21.802dB R: -114.198 + 49 = -65.19dBm LM: 65.19-(-89) = 23.81dB
Provide a Mechanism for these security models: WPA Enterprise security - Authentication WPA Enterprise security - Encryption WPA2 Enterprise security - Authentication WPA2 Enterprise security - Encryption
WPA Enterprise security - Authentication: PSK WPA Enterprise security - Encryption: TKIP WPA2 Enterprise security - Authentication: PSK WPA2 Enterprise security - Encryption: AES-CCMP
Give the following frequencies; 800MHz, 1900MHz, and 2.1GHz find the following: a. Find the wave length of each (formula is ch2, slide 3) b. Compare the antenna size of the above three systems when is the antenna's size =1/2 λ
a. 13 + 15 = 28dBm b. 10(28/10) = 631mW We know that speed of light = 3.0*10^8 m/sec So the frequency units is Hz or s^(-1) So F=800MHZ(1MHz=10^6 Hz) =800*10^(6)s^-1 Wavelength = 3.0*10^8 m/sec÷8x10^8(1/sec) = 0.375 m. 2.antenna size F=1900MHZ=19*10^8(1/sec) Wavelength=3.0*10^8 m/sec ÷ 19*10^8(1/sec) . =0.1578 m. F=2.1 GHZ (1GHZ=10^9 Hz)=2.1*10^9 (1/sec) wavelength= 3.0 * 10^8 m/sec ÷ 2.1*10^9 (1/sec) =0.142m.
Maximum bit rate in any wire or wireless channel express by Shannon capacity (C) = bandwidth x log2(1+SNR). Given a signal with signal power of 20mw and bandwidth of 1 MHz with effected total noise of 20 microwats. a. Calculate the maximum bit rate b. Calculate the maximum bit rate if the SNR = 100
a. C = bandwidth x log2(1+SNR). C = 1x106 log2(1+ (20x1000/20) = 10Mbps b. C= 1x106 log2(1+ 100) = 6.68 Mbps
