Telecommunications & Network Security Flashcards
What are the layers in the OSI Model?
(A)ll (P)eople (S)eem (T)o (N)eed (D)ata (P)rocessing 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Link
What are the OSI Layers Protocol Data Units
(D)on't forget your (S)(P)(F) at the (B)each Data = Layers 7 - 5 Segments = Layer 4 Packets = Layer 3 Frame = Layer 2 Bits = Layer 1
What are the components of Layer 1
Wiring, Wireless Modem Hubs Repeaters Access Points etc.
What are the wire types of layer 1
Twisted Pair
Coaxial Cable
Fiber Optics
What are the Attack vectors of Layer 1 (Using CIA as categories)
Integrity
- Injection/modification (noise)
Confidentiality
- Tapping (Grabbing hold of wire)
- Splicing (Breaking wire and pulling off a piece)
- Emanations ( Picking up info on the outside of wire)
Availability
- Cutting wire
What are the Controls to protect Layer 1?
Physical control of perimeter
- Security Domains
- DMZ
- Dual-homed host
Conduit
- Pressurized
Radio Frequency Management
- Directional antenna
What are the Topologies of Layer 1 (Physical Layout)
- Bus
- Tree
- Ring
- Mesh
- Star
What are the components of Layer 2
Switches
Bridges
What are Switches
- Separates collision domains based on physical wire
- Hardware
- Learns MAC addresses on segments and makes connections quickly and efficiently with no collisions
- Has more than 2 points (multi port bridge)
- full duplex
- Can filter on MAC addresses
What are Bridges
- Separates collision domains based on physical wire
- Software
- 2 Points
What does Layer 2 Provide?
1) Only Layer with 2 sub layers
- LLC (Logical Link Control - error detection)
- MAC (Media Access Control - Physical)
2) Responsible for error free, reliable transmission of data
3) Frames sized for compatibility with the MAC Protocol
4) Flow control, error detection and correction, retransmission
5) Uses MAC Addresses
What Does MAC Provide in Layer 2
1) MAC is the real address of a computer
2) NIC Card is identified by MAC address (NIC is unique for every hardware card) by
How is Addressing/Resolution and Media access determined in Layer 2?
1) ARP (Address Resolution Protocol)
- Takes IP and maps to MAC
- Stores MAC in cache
(Vulnerable if false MAC address is inserted in cache; called ARP Poisoning and is caused by unsolicited replies)
2) RARP (Reverse Address Resolution Protocol)
- Takes MAC and says give me an IP (DHCP)
How is traffic controlled with MAC in Layer 2?
1) Contention
- fight for the wire
- (CSMA/CA) Carrier Sense Multiple Access with Collision Avoidance ; used in wireless.
- (CSMA/CD)”…” with Collision Detection; waits for clear then starts talking; used in Wired
- Collision Domain; where collisions occur and cause DoS or sniffing attacks
2) Token
- Who ever has the token is first
3) Polling
- A mediator decides who communicates first (mainframes)
* *** Contention is the most popular
What is Ethernet
1) Most common form of LAN networking
2) Uses CSMA/CD
3) Supports full duplex
What are the Communication Protocols of Layer 2
Communication
- x.25; Robust
- Frame Relay ; Purchase only the needed bandwidth
- ATM (Asynchronous Transfer Mode) 100 MB or better (ie Voice/Video/Data or same channel)
- MPLS (Multi Protocol Labeling Switching) sits above layer 2 but below layer 3; allows user to specify their needs and the telephone company uses whatever they need to satisfy.
What are the Resolution Protocols of Layer 2
ARP - Address Resolution Protocol (Used Most Often)
RARP - Reverse Address Resolution Protocol
IARP - Used for Frame Relay
What are the transmission technologies of Layer 2
1) Synchronous - timing mech. with millisecs between 2 parties
* *2) Asynchronous - Uses stop and start bits. High overhead (25%)
3) Unicast - From me to you directly
4) Multicast - From me to a bunch of parties (Pay-Per-View)
5) Circuit Switched - Predictable amount of delay
* *6) Packet Switched - Takes various ways to get from me to you (Torrent)
* *7) Switched Virtual Circuits - Support packet switching
8) Permanent Virtual Circuits - To a private cloud
** Main ones
What are layer 3 devices
Router
Firewall
End Stations
What are the firewall types of Layer 3
1) Screening Router - ACLS
2) Secure Gateway (smarter than router)
- Static packet filtering
- Stateful inspection
- Dynamic Packet Filtering
3) Proxies
- Circuit Level (Physical)
- App Level (Virtual)
4) Adaptive Proxy
5) Personal Firewall
What protocols are on Layer 3
ICMP - ie Ping
IGMP - Internet Group Message Protocol; Conservation of bandwidth; requires all routers in path to pass traffic
IP
Routers
All protocols that start with “I” except IMAP
What are the firewall types of Layer 3
1) Screening Router - ACLS
2) Secure Gateway (smarter than router)
- Static packet filtering
- Stateful inspection
- Dynamic Packet Filtering
3) Proxies
- Circuit Level (Physical)
- App Level (Virtual)
4) Adaptive Proxy
5) Personal Firewall
What is Layer 3 Quality of Service Traffic Shaping
1) Help prioritize traffic so no latency
2) Does not speed traffic up but prioritizes so that you get the max speed possible
3) Stops congestion
(i. e. Video Call)
What are the network types of layer 3
LAN (Local Area Network) VLAN (Virtual Local Area Network) WAN (Wide Area Network) MAN ( Metropolitan Area Network / Campus) SAN (Storage area network)
