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CSIT127: Networks and Communications > part 3 > Flashcards

part 3 Flashcards

1
Q

station

A

Device that interfaces a user to a network

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2
Q

node

A

Device that allows 1 or more stations to access the physical network and is a transfer point for passing info through a network (often a router or telephone switch)

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3
Q

sub-network (network cloud)

A

Underlying connection of nodes and telecommunication links

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4
Q

Factors of Choosing a Routing Method

A

Method/algorithm chosen must be:

  1. Optimal
  2. Fair
  3. Robust, but not too robust
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5
Q

Least Cost Routing Algorithm

A
  • Finds all possible paths between 2 locations
  • By identifying all, also identifies least cost path
  • Determines least cost path between any pair of nodes
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6
Q

Flooding Routing

A
  • Traffic grows quickly when every node floods
  • To limit, each packet has a hop count that increments every time the packet hops

if (hopCount == networkHopLimit) -> discard packet

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7
Q

Centralized Routing

A
  • One routing table is kept at a “central” node
  • If a node needs a routing decision, central node is consulted
  • To survive central node failure, routing table should be kept at a backup location
  • Central node should be designed to support a high amount of routing requests
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8
Q

Distributed Routing

A
  • Each node has own routing table
  • Each node has to share info with other nodes so individual routing tables can be created
  • ** Individual routing tables may hold inaccurate information
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9
Q

Adaptive vs. Static Routing

A

Adaptive:
- Routing tables can change to reflect changes in network

Static:

  • Routing tables cannot change
  • Simpler but does not adapt to network congestion or failures
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10
Q

Routing Information Protocol (RIP)

A
  • Form of distance vector routing; adaptive and distributed

- Each node has own table and exchanged routing information with its neighbors

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11
Q

network congestion

A

When a network or part of a network becomes so saturated with data packets that packet transfer is noticeably impeded

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12
Q

Causes of Network Congestion

A
  1. Node and link failures
  2. High traffic
  3. Improper network planning
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13
Q

Possible Solutions to Network Congestion

A
  1. Implicit congestion control: An application can observe its own traffic and notice if packets are disappearing
  2. Explicit congestion control: The network can inform its applications that congestion has occurred and applications can take action
    * Forward Explicit Congestion Notification (FECN)
    * Backward Explicit Congestion Notification (BECN)
  3. Slow control: Flow control at a datalink layer allows 2 adjacent nodes to control the amount of traffic passing between them
  4. **Congestion avoidance: Using buffer preallocation and connection admission control
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14
Q

buffer preallocation

A

Before a node sends packets, sending node inquires in advance whether receiving node has enough buffer space

** node asks nicely before sending hehe

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15
Q

connection admission control

A

Before making a connection, user requests how much bandwith is needed, or if connection needs to be real-time

Example: Asynchronous transfer mode

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16
Q

Internet Control Message Protocol (ICMP)

A

Performs error reporting repeating for the Internet protocol (i.e. invalid IP address)

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17
Q

User Datagram Protocol (UDP)

A
  • Transport layer protocol used in place of TCP
  • Used with connectionless applications as opposed to connection-oriented like in TCP
  • Encapsulates a header onto an application packet but the header is much simpler than TCP
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18
Q

Multiprotocol Label Switching

A
  • Additional label/s encapsulated onto the front of an IP packet
  • Used to move Internet packets more quickly through routers
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19
Q

Address Resolution Protocol (ARP)

A
  • Translates IP address into MAC so frame can be delivered to proper workstation
  • Allows packet to find right destination workstation since LAN does not use IP addresses to deliver frames, uses MAC instead
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20
Q

Tunneling Protocols and Virtual Private Networks (VPNs)

A
  • Creates secure connection through internet by using a tunneling protocol and security procedures
  • Two types: Point-to-point TP (PPTP), IPSEC
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21
Q

Point-to-Point TP (PPTP)

A

Extension of point-to-point protocol, used for communication between 2 computers using a serial connection

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22
Q

IPSEC

A

Set of protocols developed to support the secure exchange of data packets at IP layer

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23
Q

Asynchronous Transfer Mode (ATM)

A
  • Sends data in small packets called “cells”
  • Virtual circuit/connection must be established before the 2 end points can exchange data
  • 4 classes of service: Constant Bit Rate Service (CBR), Variable Bit Rate (VBR), Available Bit Rate (ABR), Unspecified Bit Rate (UBR)
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24
Q

Constant Bit Rate Service (CBR)

A

Delivers high speed, continuous data stream that can be used with transition-intensive applications

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25
Q

Variable Bit Rate (VBR)

A

Used for real-time applications (i.e. compressed interactive radio) and non-real-time (i.e. sending email with large, multimedia attachments)

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26
Q

Available Bit Rate (ABR)

A

Used for “bursty” traffic that does not need to be transmitted immediately

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27
Q

Unspecified Bit Rate (UBR)

A

For lower rate traffic that may get held up, may even be discarded part way through transmission if congestion occurs

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28
Q

Advantages of ATM

A
  • Different classes of service

- Ability to operate over many types of media and network topologies

29
Q

Disadvantages of ATM

A
  • Potentially higher costs

- Higher level of complexity

30
Q

Bluetooth

A
  • Designed for very short ranges

- Communicates using small, low-power transceivers called radio modules

31
Q

Link Manager

A

Special software that helps identify other Bluetooth devices, creating a link between them and send/receive digital data

Examples: headphones, smart TVs, keyboard/mouse

32
Q

Zig Bee

A

Designed for applications that require devices with long battery life and can transmit data at distances between 10-15 meters

33
Q

WiGig

A
  • Can transfer video and sound
  • Short-range primarily used at home
  • Use confined to space within a room with few or no obstacles
34
Q

RFID

A

Small chips containing a CPU, memory, and other electronic circuitry plus an antenna

35
Q

NFC (Near Field Communication)

A
  • Similar to RFID
  • Includes more flexible information (i.e. web addresses, commands)
  • Very short distance (i.e. 5-10 cm)
36
Q

Satellite

A

Used to transmit data over very long distances

Example: GPS, satellite radio

37
Q

Cellular

A
  • Built around concept of low-power transmitters

- Transmission towers spread throughout a geographic area

38
Q

Wireless LAN

A
  • Extension of wired LAN

- Uses an Access Point (AP) which relays data signals among all of the devices on the wired network

39
Q

Fixed Broadband Wireless

A

Used in areas where wired internet connectivity may not be available

40
Q

Internet of Things (IoT)

A

Type and amount of data that can be collected from smart sensors, transmitted to servers, analyzed in real-time or saved for later analysis

41
Q

Examples of Wireless Applications

A
  • Military
  • Education
  • Travel
  • Offices
  • Health care
  • Home control systems
42
Q

Wireless Networking Advantages

A
  • Mobility
  • Easier and less expensive installation
  • Increased reliability
  • Disaster recovery
  • Future applications
43
Q

Wireless Networking Disadvantages

A
  • Radio signal interference
  • Security
  • “Health risks”
44
Q

computer virus

A

Small program that alters the way a computer operates and often does various types of damage (i.e. corrupting data)

45
Q

worms

A

Program that copies itself from one system to another over a network without the assistance of a human being

46
Q

2 Popular Forms of Attacks

A
  1. Socially engineered

2. Exploiting known vulnerabilities in OS or application software

47
Q

Denial of Service (DOS) or Distributed (DDOS)

A

Bombard site with so many messages that the site is incapable of answering a valid request

48
Q

Ping Storm

A

Internet ping program used to send flood of packets to a server

49
Q

Email Bombing

A

Excessive amount of unwanted email sent to someone

50
Q

Smurfing

A

Attacks a network by exploiting IP broadcast operations

51
Q

Botnets

A

Malicious programs that take over operation on a comprised computer

52
Q

Spoofing

A

User creates a packet that appears to be something else or from someone else

53
Q

Phishing

A

Hackers create emails which look as if they are coming from a legit source but the hacker is attempting to get sensitive information

54
Q

Pharming

A

Hacker redirects unknowing user to bogus look-alike website

55
Q

Rootkit

A

Defies detection and takes over the user’s computer

56
Q

Keylogger

A

Software system that secretly captures and records keystrokes

57
Q

cryptography

A

Study of creating and using encryption and decryption techniques

58
Q

Firewall

A

System or combination of systems that supports an access control policy between 2 networks

  • Limits types of transactions entering and leaving a system
59
Q

3 Types of Firewalls

A
  1. Packet filter
    - A router that has been programmed to filter out or allow to pass certain IP addresses or TCP port numbers
  2. Proxy server
    - More advanced firewall that acts as a doorman into a corporate network
  3. Application layer
    - Inspects all packets coming into or leaving a connection using the application layer of the TCP/IP suite
60
Q

Controlling Access

A
  • Deciding who has access to what
  • Limiting time of day and day of week access
  • Limiting access from a location, such as not allowing a user to use a remote login during certain periods of time
61
Q

WLAN Security

A
  • Broadcasting network traffic over the airwaves
  • Security implementations are analogous to those in Ethernet
  • WLANs are far more exposed to intrusion because the medium is not contained
62
Q

Attacks Against WLANs

A
  1. Hardware theft
    - Device may contain information that can assist someone in breaking into the network
  2. AP impersonation
    - A rogue AP can impersonate a valid device
  3. Passive monitoring
    - Data transmissions can be monitored
  4. Denial of service (DoS)
    - Flood the network with transmissions and deny others access to the AP
63
Q

authentication

A
  • Process that verifies that the client device has permission to access the network
  • Each WLAN client can be given the SSID of the network manually or automatically
  • Turning off SSID broadcast can only protect your network against someone finding it unintentionally
64
Q

privacy

A
  • Ensures that transmissions are not read by unauthorized users
  • Accomplished with data encryption
65
Q

Wired Equivalent Privacy (WEP)

A
  • Data encryption specification for wireless devices
  • 2 versions: 64-bit and 128-bit encryption
  • Attackers can decrypt a 128-bit WEP key in minutes :(
  • Uses weak RC4 implementation
66
Q

Wi-Fi Protected Access

A
  • Standard for network authentication and encryption
  • Uses a 128-bit pre-shared key (PSK)
  • WPA-PSK uses a different encryption key for each client device, for each packet, and for each session
  • WPA employs temporal key integral protocol (TKIP) which provides per-packet key-mixing
  • TKIP also provides message integrity check (MIC)
  • KIP uses a 48-bit hashed initialization vector
67
Q

IEEE 802.11i and IEEE 802.1x

A
  • Define a robust security network association (RSNA)
  • Mutual authentication between client devices and AP
  • Controlled access to the network
  • Establishment of security keys
  • Key management
68
Q

Push-Button Wireless Security

A
  • New method of configuring wireless devices

- Automatically configures the security settings

69
Q

Additional WLAN Security Strategies

A
  • Reduce WLAN transmission power
  • Change the default security settings on the APs
  • Antivirus and antispyware software
  • Separate WLAN transmissions from wired network which place a firewall between the WLAN and the wired LAN

CSIT127: Networks and Communications (4 decks)

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