Vii - Telecommunications And Network Security

Front 1

Difference between Simplex, Half-Duplex and Full-Duplex Communication

Back 1

Simplex - One way communication (like listening to a radio)

Half-Duplex - Sends or receives information one at a time (like a Wallie-talkie).

Full-Duplex - Sends and receives information simultaneously (like a face to face conversation)

Front 2

Baseband vs. Broadband

Back 2

Baseband networks have one channel. Ethernet is an example.

Broadband networks have multiple channels, and can send multiple signals simultaneously (like cable tv).

Front 3

Analog vs. Digital

Back 3

Analog is what our ears can hear, digital is 1's and 0's.

Front 4

LAN vs. MAN vs. WAN vs. GAN vs. PAN

Back 4

LAN (Local Area Network) - Usually confined to a building.

MAN (Metropolitan Area Network) - Usually covers a city, campus or office park.

WAN (Wide Area Network) - Usually covers multiple cities, states or even countries.

GAN (Global Area Network) - GIG is an example of this (It is the DoD's global network

PAN (Personal Area Network) - Like Bluetooth

Front 5

Internet vs. Intranet vs. Extranet

Back 5

Internet - Global collection of peered networks running TCP/IP, providing "best effort service"

Intranet - Privately owned network running TCP/IP.

Extranet - Connection between two Intranets, such as a connection between business partners.

Front 6

Circuit-Switched vs. Packet-Switched Networks

Back 6

Circuit-Switched - A dedicated circuit or channel (portion of a circuit) is dedicated between two nodes. This is what a T1 line is.

Packet-Switched - Data is broken into packets which are sent individually. The packets can choose the best channel to proceed down, and if there is a failure, can proceed down another channel.

Front 7

Predecessor of the Internet

Back 7

ARPAnet

Created in the early 60's by Defense Advanced Research Projects Agency (DARPA). It was the first use of Packet-Switched technology.

Front 8

Quality of Service

Back 8

A way to rank information being sent over a network by it's priority. VoIP would receive a higher priority than would eMail being sent.

Front 9

SMTP

Back 9

Simple Mail Transfer Protocol

Front 10

Layered Design

Back 10

Network models are layered, and one layer does not usually directly effect another layer. For example, changing your PC from a wireless connection to a wired connection, does not affect your web browser.

Front 11

Basic description of Network Models and Stacks

Back 11

Network Model - How a network protocol suite operates (i.e. OS or TCP/IP)

Network Stack - Programming for hardware or software to enable use of a Network Model

Front 12

What is OSI?

Back 12

Open System Interconnection

Abstract. Used as reference point to mark layers within a network.

Front 13

Name the seven layers of OSI

Back 13

Layer 1: Physical
Layer 2: Data Link
Layer 3: Network
Layer 4: Transport
Layer 5: Session
Layer 6: Presentation
Layer 7: Application

Front 14

What was the OSI model formally called?

Back 14

X.200 - Information Technology - Open Systems Interconnection - Basic Reference Model.

Front 15

Layer 1: Physical Layer

Back 15

Includes bits, energy which encapsulates the bits (electricity, light, radio waves, etc), and the medium used to carry them (copper or fiber optic cables).

Front 16

Layer 2: Data Link... What is it, and what are it's 2 sub-layers?

Back 16

Handles access to the physical layer as well as local area network communication (LLC). Examples would be an ethernet card and it's MAC address, as well as switches and bridges.

Two sub-layers: Media Control (MAC) and Logical Link Control (LLC). MAC touches Layer 1 and LLC touches Layer 3.

Front 17

Layer 3: Network

Back 17

This is the routing (moving data from a system on one LAN to a system on another. IP addresses and routers liven on Layer 3.

Front 18

Layer 4: Transport

Back 18

Packet sequencing, flow control and error detection. TCP and UDP are Layer 4 protocols.

Front 19

Layer 5: Session

Back 19

Manages sessions, providing MAINTENANCE on connections. A good way to remember the session layer's function is "connection between applications". Uses Simplex, Half-Duplex and Full-Duplex communication.

Front 20

Layer 6: Presentation

Back 20

Presents the data to the application (and end user) in a comprehensible way. This includes data conversion with character sets such as ASCII and image formats such as JPEG, TIFF and GIF.

Front 21

Layer 7: Application

Back 21

Web browser, word processor, instant messaging client, etc. Also includes Telnet and FTP.

Front 22

Please Do Not Throw Sausage Pizza Away

or...

All People Seem To Need Data Processing

Back 22

Mnemonic to help recall the layers (1-7) or (7-1)

Front 23

What is the formal name of TCP/IP, and how does it relate with OSI

Back 23

Internet Protocol Suite. TCP/IP is simpler than OSI because it only has 4 layers instead of 7.

Front 24

Name the 4 TCP/IP layers

Back 24

1) Network Access Layer
2) Internet Layer
3) Host-to Host Transport Layer
4) Application Layer

Front 25

Network Access Layer (of TCP /IP)

Back 25

Combines the Physical and Data Link layers of the OSI model

Front 26

Internet Layer

Back 26

This aligns with the Network layer of the OSI model. Although the OSI layer is called the Network layer, it should not be confused with the Network layer of TCP/IP.

Front 27

Host-to-Host Transport Layer

Back 27

Also called the Transport Layer. Connects the Internet Layer to the Application Layer. TCP and UDP are the two transport layer protocols.

Front 28

Application Layer (of TCP/IP)

Back 28

Combines layers 5 through 7 of the OSI model (Session, Presentation and Application).

Front 29

Encapsulation

Back 29

Takes information form a higher layer and adds a header to it. Each layer's information (data) could be encapsulated to be sent to the next layer.

Front 30

PDU

Back 30

Protocol Data Units

Front 31

The reverse of Encapsulation (including a description of the process)

Back 31

De-Multiplexing (or De-Encapsulation)

Moving up the stack, bits are converted to Ethernet frames, frames are converted to IP packets, packets are converted to TCP segments, segments are converted to application data.

Front 32

What is included in TCP/IP, and at what layers?

Back 32

IPv4 and IPv6 (Layer 3)

TCP and UDP (Layer 4)

Several protocols at Layers 5-7 including Telnet, FTP, SSH, etc.

Front 33

MAC Addresses

Back 33

Media Access Control

The unique address of the Ethernet network interface card (NIC). Typically 48 or 64 bits long, with the first 24 bits being the OUI, and the last numbers being the serial number.

Front 34

OUI

Back 34

Organizationally Unique Identifier

Front 35

Producer of OUI's

Back 35

Institute of Electrical and Electronics Engineers (IEEE), Incorporated Registration Authority

Front 36

Basics of IPv4 and IPv6

Back 36

Internet Protocol version 4 and version 6

IPv4 uses 32 bit source (192.168.2.2) and IPv6 uses 128 bit (fco1::20c:29ff;feef:1138/64).

Front 37

8 key fields of an IPv4 Header

Back 37

1) Version
2) IHL: Length of header
3) Type of Service: Precedence of the packet
4) Identification, Flags, Offset: Used for IP fragmentation
5) Time to Live: to end routing loops
6) Protocol: Embedded protocol (UDP, TCP, etc.)
7) Source and Destination IP addresses
8) Optional: Options and padding

Front 38

MTU

Back 38

Maximum Transmission Unit

Refers to the max size of packet that a network can handle. A typical size is 1500 bytes.

Front 39

IPID

Back 39

IP Identification Field

Used to re-associate packets that have been broken apart because they are too large.

Front 40

Flags

Back 40

Determines whether fragmentation is allowed and whether more fragments are coming.

Front 41

Fragment Offset

Back 41

Tells where the offset occurs in fragmentation ("Copy this data begninning at offset 1480").

Front 42

IPv6 Header (5 fields)

Back 42

1) Version
2) Traffic Class and Flow Label: Used for Quality of Service
3) Payload Length (Length of the data not including the header)
4) Next Header (next embedded protocol header)
5) Hop Limit: to end routing loops

Front 43

IPv6 configuration of IPv6 addresses

Back 43

Autoconfiguration (no need for static addressing or DHCP).

Front 44

Difference between Global and Link Addresses

Back 44

Global is the communication address to the rest of the world.

Link is used for local network communication

Front 45

What does :: replace in an IPv6 address?

Back 45

Consecutive zeroes

Front 46

What are 2 ways in which IPv6 can cause security issues?

Back 46

1) It will automatically configure a link-local address without the need for any other IPv6-enabled infrastructure.

2) ISPs also enable IPv6 service without the customer's knowledge.

Front 47

Classful Networks

Back 47

The original IPv4 networks (before 1993). Classes A through E. These were inflexible and resulted in the waste of 250 IP addresses.

Front 48

Classless Inter-Domain Routing (CIDR)

Back 48

Allows for expansive network sizes beyond the arbitrary amounts of a Classful network.

Front 49

RFC (short for Request for Comments) 1918 Addressing

Back 49

Private addresses that are used for internal traffic and do not route through the internet. This allows for reuse of IP addresses across several networks without wasting the scarce IPv4 addresses.

Front 50

What are some examples of RFC 1918 addresses?

Back 50

10.0.0.0 - 10.255.255.255 (10.0.0.0/8)

172.16.0.0 - 172.31.255.255 (172.16.0.0/12)

192.168.0.0 - 192.168.255.255 (192.168.0.0/16)

Front 51

Network Address Translation (NAT)

Back 51

Used to translate IP addresses. NAT allows an RFC 1918 address to communicate with the web.

NAT hides the origin of the packet with the router or firewall acting as the NAT gateway.

Front 52

What are 3 types of NAT?

Back 52

1) Static NAT - Makes a one-to-one translation between addresses.
2) Pool NAT (Dynamic NAT) - Reserves a group of Public IP addresses to be used and then returned.
3) Port Address Translation (PAT) -Takes a many-to-one approach in taking several private addresses and converting them to one public address. Common solution for homes and small offices.

Front 53

ARP

Back 53

Address Resolution Protocol - Used to translate between layer 2 MAC addresses and layer 3 IP addresses.
"Who has IP address 192.168.2.140, tell me."

Front 54

RARP

Back 54

Used by diskless workstations to request an IP address. "Who has MAC address at 00:40:96:29::06:51, tell 00:40:96:29:06:51." RARP is essentially asking, "Who am I?"

Front 55

Unicast

Back 55

One-to-one public traffic (such as surfing on the internet) or one-to-all while on a LAN.

Front 56

Multicast

Back 56

Uses Class D addresses when used on IPv4. A common multicast use is streaming audio or video.

Front 57

Broadcast traffic

Back 57

Broken up into limited broadcast and directed broadcast. Limited is never sent across a router and it's address is 255.255.255.255.

Directed (or net-directed) can be broadcast from a remote network.

Front 58

Layer 2 Broadcast

Back 58

Reaches all nodes in a broadcast domain (such as a switch).

Front 59

Promiscuous Network Access

Back 59

Ability to access all unicast traffic on a network.

Front 60

NIDS

Back 60

Networked Intrusion Detection System

Requires promiscuous network access

Front 61

TCP

Back 61

Transmission Control Protocol

A reliable layer 4 protocol that uses a three-way handshake to create connections over a network. Can reorder segments that arrive out of order, and retransmit missing segments.

Front 62

Key TCP Header Fields (four of them)

Back 62

20 bytes long and contains a number of fields such as...

Source and Destination port

Sequence and Acknowledgement Numbers

TCP Flags

Window Size (the amount of data that may be sent before receiving acknowledgement).

Front 63

TCP Ports... What are they and what are the 2 different types?

Back 63

Connects from a source port to a destination port

Reserved port - From 0 to 1023. Requires super user access to open a reserved port.

Ephemeral ports - 1024 - 65535. Any user can open one of these as long as they are unused.

Front 64

IANA

Back 64

Internet Assigned Numbers Authority

Front 65

Socket vs. Socket Pair

Back 65

A socket is a combination of an IP address and a TCP or UDP port on one node.

A socket pair describes a connection between two sockets (inbound and outbound)

Front 66

What are the 8 TCP Flags (with the first 6 being the original ones)?

Back 66

1) URG - Packet contains urgent data
2) ACK - Acknowledge received data
3) PSH - Push data to application layer
4) RST - Reset (tear down) a connection
5) SYN - Synchronize a connection
6) FIN - Finish a connection (gracefully)
7) CWR - Congestion Window Reduced
8) ECE - Explicit Congestion Notification Echo

Front 67

What are flags primary purpose?

Back 67

Manage congestion (slowness) along a network path.

Front 68

What are the 3 steps of the TCP Handshake?

Back 68

1) Synchronize (SYN)
2) Synchronize (SYN) - Acknowledge(ACK)
3) Acknowledge (ACK)

Front 69

What is an acknowledgement number?

Back 69

The connection begins with a number and then that number is incremented as the message continues. This way, if one side ACK's a wrong number, then the sender knows their was a failure.

Front 70

What is a nick name for UDP

Back 70

Send and Pray (since there is no handshake, session or reliability).

Front 71

What layer does UDP operate at?

Back 71

Layer 4 (Transport)

Front 72

ICMP

Back 72

Internet Control Message Protocol

A helper protocol that helps with error control. Does not know ports, but uses echo request and echo reply with time to live to determine health of transmission.

Front 73

Ping

Back 73

Echo request followed by Echo reply

Front 74

TTL

Back 74

Time to Live

A counter to ensure that a packet gets to Live

Front 75

Traceroute

Back 75

Determines all of the routers (hops) that are in a path. The TTL drops one level each time a router is hit. The Traceroute learns this series of drops to determine the number or routers.

Front 76

Name 9 protocols at TCP/IP Application Layer

Back 76

1) Telnet
2) FTP
3) TFTP
4) SSH
5) SMTP, POP and IMAP
6) DNS
7) SNMP
8) HTTP and HTTPS
9) BOOTP and DHCP

Front 77

Telnet

Back 77

Terminal emulation over a network.

Weak b/c it provides no confidentiality and limited integrity.

Front 78

FTP

Back 78

File Transfer Protocol

Used to transfer to and from servers. Also has no confidentiality and integrity

Uses control connection port (sent) 21 and data connection port (transferred) 20

Front 79

TFTP

Back 79

Trivial File Transfer Protocol

Runs on UDP port 69. A simpler way to transfer files while saving router configurations or "bootstrapping".

Front 80

SSH

Back 80

Designed as a secure replacement for Telnet, FTP, etc. Provides confidentiality, integrity and secure authentication. Listens on port 22. Currently on version SSHv2.

Front 81

SMTP

Back 81

Simple Mail Transfer Protocol

Port 25. Used to transfer email between servers.

Front 82

POP

Back 82

Post Office Protocol

Port 110. Client-server email access.

Front 83

IMAP

Back 83

Internet Message Access Protocol

Port 143. Client-server email access

Front 84

DNS

Back 84

Domain Name System

Gets names when given an IP or visa versa. Uses UDP or TCP port 53.

Can be unreliable when using UDP and provides no authentication.

Front 85

DNSSEC

Back 85

Domain Name Server Security Extensions

Provides authentication and security to DNS by using Public Key Encryption. It does not provide confidentiality. Not widely used b/c of the difficulty with internet public key encryption.

Front 86

SNMP

Back 86

Simple Network Management Protocol

Used to monitor network devices (interface status, bandwidth utilization, CPU temperature, etc.)

Front 87

HTTP and HTTPS

Back 87

Hypertext Transfer Protocol and Hypertext Transfer Protocol Secure

Both transfer data via the web. HTTP on port 80 and HTTPS on 443

Front 88

BOOTP

Back 88

Bootstrap Protocol

Allows loading an OS via network

Front 89

DHCP

Back 89

Dynamic Host Configuration Protocol

An improvement on BOOTP. Both BOOTP and DHCP use port 67 (servers) and 68 (clients)

Front 90

How to reduce electro magnetic interference (EMI) in cabling

Back 90

Twisted pairs reduce this by having one wire carrying data out and one wire receiving data.

Front 91

UTP

Back 91

Unshielded Twisted Pair

Front 92

What makes a CAT 6 cable different than a CAT 3 cable?

Back 92

Tighter twisting and therefore more dampening. CAT 6 is designed for gigabit networking.

Front 93

STP

Back 93

Shielded Twisted Pair

More expensive and rigid, but less susceptible to EMI.

Front 94

What are the speeds of the various categories of cables?

Back 94

Cat 1: <1 mbps (Analog voice)
Cat 2: 4 mbps (ARCNET)
Cat 3: 10 mbps (10baseT Ethernet)
Cat 4: 16 mbps (Token Ring)
Cat 5: 100 mbps (100baseT Ethernet)
Cat 5e: 1000 mbps (1000baseT Ethernet)
Cat 6: 1000 mbps (1000baseT Ethernet)

Front 95

Difference between Coaxial cables and Twisted Pair

Back 95

Coaxial has thicker and better insulation and therefore more resistant to EMI, and allows for higher bandwidth. Thinnet and Thicknet are 2 older types of coaxial cable.

Front 96

Fiber

Back 96

Fiber Optic Network Cable.

Uses light to carry more data faster with no EMI when compared with twisted pair or coaxial cable.

Front 97

Wavelength Division Multiplexing (WDM)

Back 97

Allows fiber to carry multiple signals

Front 98

Ethernet

Back 98

Transfers data via frames. Occupies layer 1 (physical medium) and layer 2 (frames). Started as physical bus topology and has progressed to physical star.

Front 99

CSMA

Back 99

Carrier Sense Multiple Access

Used to prevent collision with regards to the Baseband Ethernet traffic.

Front 100

Difference between CSMA/CA and CSMA/CD

Back 100

CSMA/CD is used for systems that can send and receive simultaneously (such as wired Ethernet).

CSMA/CA (Collision Avoidance) is used by those that cannot send and receive simultaneously. CD is superior b/c it detects collisions immediately.

Front 101

ARCNET and Token Ring

Back 101

ARCNET (Attached Resource Computer Network) and Token Ring are legacy LAN technologies.

Both use tokens to pass network data. Has not collisions, but not as fast and more expensive than Etherrnet.

Front 102

FDDI

Back 102

Fiber Distributed Data Interface

Legacy LAN technology using rotating rings for fault tolerance.

Front 103

Bus

Back 103

Connects system in a string. A problem between two devices will result in problems all the way down the string.

Front 104

Tree Topology

Back 104

Hierarchical network in which a root node (often a mainframe) feeds branches which divide

Front 105

Ring

Back 105

Strings nodes in a ring, so that if you follow the string, you will end up where you started.

Front 106

Star Topology

Back 106

Each node is connected to a central device such as a hub or switch.

More cabling is required, but has much better fault tolerance.

Front 107

Mesh

Back 107

Interconnects network nodes to each other. Used to ensure HA (high availability) so that if one server goes down, there is another that can shoulder the load.

Front 108

T1s and T3s

Back 108

T Carriers are US based while E Carriers are Europe based.

T1= 1.5 Megabit circuit that carries 24 64 bit Digital Signal (DS). One T1 carries one DS1

T3= 28 bundled T1s (45 Megabits)

Front 109

E1 and E3

Back 109

Europe's version of T1 and T3.

Higher bandwidth at E1 vs T1 (2.048 mbs vs 1.5 mbs), but less at the E3 level (34 mbs compared with 45 mbs for T3).

Front 110

SONET

Back 110

Synchronous Optical Networking

Carries multiple T circuits via fiber optic cable. Uses physical fiber ring for redundancy.

Front 111

Forwarding Tables

Back 111

Used to tell a bridge which port to send data to.

Front 112

Source Routing

Back 112

The necessary routing information is contained in the header of the packet and does not require forwarding tables.

Front 113

What is the difference between two LANs connected with a bridge and two LANs connected with a router?

Back 113

Those connected with a bridge are just extended, whereas those connected with a router have formed an inter-network.

Front 114

Gateway

Back 114

Software on a device that acts as a type of router, but actually is usually involved in translations between different types of environments. Internetwork Packet Exchange (IPX) is an example.

Front 115

3 Firewalls and 2 subtypes

Back 115

1) Packet-Filtering - The simplest and weakest of the firewalls
2) Stateful Firewall - Looks back over it's ACLs to see if it should be allowed.
3) Proxy Firewall - Middleman who checks packages.
3a) Application Proxy - Inspects package up through the application layer. Requires one proxy for each service (FTP, NTP, SMTP, etc).
3b) Circuit-level Proxy - Works at the session layer and is concerned with the source and destination addresses. SOCKS is an example of a circuit-level proxy gateway.

Front 116

Kernel Proxy Firewall

Back 116

Fifth Generation Firewall

Creates a new virtual network to examine the specific parts of the packet that are necessary.

Front 117

Dual-Homed Firewall

Back 117

One host facing the internal network and the other facing the external world.

Can also be multihomed

Front 118

Screened Subnet

Back 118

A secondary firewall inside the initial firewall to create a DMZ

Front 119

DNS Pharming Attack

Back 119

An attacker changes the routing IP address to redirect to a malicious site.

Front 120

Dedicated Link

Back 120

Leased line or point-to-point link. Connects two destinations via a WAN

Front 121

SMDS

Back 121

Switched Multimegabit Data Service

Allows two LANs to communicate via a MAN or WAN. Not used much anymore.

Front 122

HSSI

Back 122

High-Speed Serial Interface

Interface that connects routers and other physical layer devices to ATM or Frame Relay

Front 123

SIP

Back 123

Session Initiation Protocol

Relies on 3 way handshake to secure VoIP sessions.

Front 124

FHSS vs DSSS

Back 124

Frequency Hopping Spread Spectrum uses part of the bandwidth while Direct Sequence Spread Spectrum uses all of the bandwidth.

Front 125

8 Wireless standards

Back 125

1) 802.11 - Dictates how wireless clients and their APs communicate.
2) 802.11b - Most common standard today. 2.4 GHz
3) 802.11a - 5 GHz (uses OFDM)
4) 802.11e - Provides for QoS
5) 802.11f - Provides for roaming between APs
6) 802.11g - Provides for faster speed over 802.11b
7) 802.11h - Allows for global 802.11a
8) 802.11i - Incorporates security into the 802.11 protocols

Front 126

Bluejacking

Back 126

An unsolicited bluetooth message is sent in an effort to get their contact information into your phone.

Front 127

WAP

Back 127

Wireless Application Protocol

An industry driven protocol stack. Designed to use limited resources to gain information such as weather, stock quotes, etc.

Front 128

Encryption of a data sent over a cell phone. Is it End-to-End and why?

Back 128

No. It will be encrypted over the wireless portion of it's journey, but not over the wired portion of the journey.

Front 129

Mobile Technology Generations

Back 129

1G: Analog/Voice
2G: Voice with Low speed data
2 1/2G: Higher bandwidth than 2G
3G: Voice and Data with packet-switched technology

Front 130

What can be compromised if the OS does not have packet forwarding or routing disabled?

Back 130

Dual-homed firewalls

Front 131

Protocol

Back 131

A set of rules that dictate how computers communicate over networks

Front 132

TKIP

Back 132

Temporal Key Integrity Protocol

Generates random values in wireless encryption.