Chapter 5 - Networks and Telecommunications Flashcards
Open Systems Interconnection Reference Model (OSI) Layers
Layer 1: Physical
Layer 2: Data link
Layer 3: Network
Layer 4: Transport
Layer 5: Session
Layer 6: Presentation
Layer 7: Application
Function of Layer 1 of the OSI
Establishes and manages the physical transmission of data between network devices
Function of Layer 2 of the OSI
Responsible for the transfer of data between adjacent nodes on a network segment using MAC addresses to identify devices
Function of Layer 3 of the OSI
Routing and forwarding data packets between different networks, using IP addresses
Function of Layer 4 of the OSI
Responsible for ensuring reliable end-to-end communications and maintenance between applications
Function of Layer 5 of the OSI
Opens, closes, and manages sessions between end-user application processes
Function of Layer 6 of the OSI
Ensures that data is formatted and encoded in a way that the application can understand. Includes tasks like data translation and encryption/decryption
Function of Layer 7 of the OSI
Provides the protocols that end-user applications use to interact with the network. For example: HTTP for browsing the web and FTP for file transfer
WAN
Wide-area network
Example of a WAN
The internet
Disadvantage of WANs
Data security cannot be guaranteed
How can we make data more secure as it travels across a WAN
Encrypt it
LAN
Local-area network
Function of a LAN
Provide network connectivity for computers that are in the same geographic area and are typically connected with hubs and switches
Hubs
devices that contain plugs and ports to connect ethernet cables for different network systems
Switches
Receive packets of information, look at the destination MAC address, and then send the packet there. (perform intelligent filtering)
Disadvantage of a LAN
Oftentimes, they do not protect themselves from each other. So if one becomes infected, malware can quickly spread to all the devices on the network
Example of a LAN
Ethernet networks (the most common LAN)
The ethernet standard
Defines how computers use media access control (MAC) addresses to communicate with each other
The ethernet standard governs which layers of the OSI?
Physical (layer 1) and data link (layer 2)
Virtual LANs
A collection of logically related network devices that are viewed as a network segment. Allows administrators the ability to separate network segments without physically separating the cabling
Transmission control protocol (TCP) and internet protocol (IP) are apart of which layers of the OSI reference model?
Network and transport
TCP and IP
a suite of protocols that govern all activity across the internet and through most corporate and home networks
Network port
A number that tells a receiving device where to send messages it receives
IPv4 addresses
4-byte, 32-bit; still the most common
IPv6 addresses
128-bits long; more complex and secure
Dynamic Host Configuration Protocol (DHCP)
Provides a computer with an IPv4 address, a subnet mask, and other essential communication information
Internet Control Message Protocol (ICMP)
A management and control protocol for IP that delivers messages about the health of the network
Vulnerability of ICMP
Attackers can use it to create a DoS attack
Reconnaissance
Gathering information about a network for use in a future attack
Eavesdropping
When an attacker taps a data cable to see all the data passing through it
Denial-of-service (DoS)
Flooding a network with traffic and shutting down a single point of failure
Distributed denial-of-service (DDoS)
Uses multiple compromised systems to flood the network from many different directions
Telephony denial-of-service (TDoS)
Attempts to prevent telephone calls from being successfully initiated or received by some person or organization
Firewalls
Controls the flow of traffic by preventing unauthorized network traffic from entering or leaving a particular portion of the network
Border firewalls
Separate the protected network from the internet
Three parts of Unified Threat Management
- URL filter - filters web traffic by examining the URL instead of the IP
- Content inspection - looks at network packet content to determine if the packet should be allowed to pass
- Malware inspection - looks at packet content for signs of malware
Network Access Control (NAC)
Enables you to add more security requirements before allowing a device to connect to the network
Wireless access points (WAPs)
A radio that sends and receives networking information over the air between wireless devices and the wired network
Who can attempt to connect to wireless access points?
Anyone who is in radio range
Examples of wireless network security controls
- VPNs
- Wireless encryption (such as WEP, CCMP, WPA)
- MAC address filtering
- SSID broadcast
