Networking Fundamentals (THM) Flashcards
What is computer networking?
Connecting devices so that they can share data.
If Humans have 1)Names and 2) fingerprints, what do computers have?
1) IP Addresses
2) MAC Addresses
What does IP and MAC stand for?
Internet Protocol and Media Access Control
What are 2 IP addressing schemes and their respective number systems?
1) IPV4 (2^32)
2) IPV6 (2^128)
What is an IP address divided by?
4 Octets
What is Ping and what does it use?
Ping is a networking tool that uses ICMP packets to verify network connection and performance.
What is ICMP?
Internet Control Message Protocol
What is LAN?
Local Area Network
What is a LAN Topology?
The configuration of a LAN.
What are the 3 types of Lan Topologies?
Star
Bus
Ring
What is the most efficient LAN topology? Give a positive and negative.
Star
Scalable and most efficient
Expensive
What is the cheapest LAN topology? Positive and Negative?
Bus
Easy set up and cost efficient
Can bottleneck and slowdown, dependent on backbone cable
What is the easiest LAN topology to fix? Positive and Negative?
Ring
Easy set up, more efficient than Bus topology
Dependent on every connected device and cable
What is a switch?
A device that connects other devices and tracks which port those devices are connected to.
What is a router?
A device that connects and passes data between networks.
Device that configures port forwarding.
What is routing?
Process of data travelling across networks.
What is ARP?
Address Resolution Protocol
What is a cache?
A ledger of addresses
What does ARP do?
Allows devices to connect to networks by associating their MAC to an IP. Each device on a network will track the MAC addresses associated to IPs on a network.
How does ARP work?
1)ARP Request
2)ARP Reply
What is an ARP Request?
Message sent on a network requesting the MAC address associated with a known IP address.
What is an ARP Reply?
If the MAC address associated with a known IP address is known by the device, it sends the MAC address to the device that made the ARP Request.
What does a device do after receiving an ARP Reply?
Stores the MAC address associated with an IP into its cache.
What is DHCP?
Dynamic Host Configuration Protocol
What are the 4 steps of DHCP?
1)DHCP Discover
2)DHCP Offer
3)DHCP Request
4)DHCP Ack
What does DHCP Discover attempt to do?
Connect to a DHCP server
What is an OSI model?
Open Systems Interconnection model
What are the 7 steps in an OSI model?
1)Physical
2)Data Link
3)Network
4)Transport
5)Session
6)Presentation
7)Application
What is encapsulation? What does it have to do with the OSI model?
Information being added to data.
Encapsulation occurs at every step of the OSI model.
What is the Physical layer of the OSI model?
Devices use electrical signals to transfer data between each other in a binary numbering system.
What is the Data Link layer of the OSI model?
Physical addressing of devices and presenting that data in suitable formats.
What is a NIC? What does it have? Which layer of the OSI model is it involved in?
1) Network Interface Card.
2) The MAC address physically burned into it.
3) The Data Link layer.
What is the Network layer of the OSI model?
Where routing and re-assembly of data occurs.
Name 2 different protocols in the Network layer of the OSI model
OSPF
RIP
What is OSPF? (Network layer)
Open Shortest Path First
What is RIP? (Network layer)
Routing Information Protocol
What do devices in the Network layer of the OSI model use to communicate? What do they send and receive?
IP addresses
Packets
What is the Transport layer of the OSI model?
How data is transmitted in a network and connection type
What are 2 different protocols in the Transport layer of the OSI model?
TCP & UDP
What is TCP? Which layer does it fit in the OSI model?
Transmission Control Protocol
Transport
What is UDP? Which layer does it fit in the OSI model?
User Datagram Protocol
Transport
What is the Session layer of the OSI model?
When a connection between 2 devices is made.
What is a technical term for an established connection? Which layer of the OSI model does this correspond to?
Session
Session
What is the Presentation layer of the OSI model?
Translates software data from the application layer so that it’s usable by the other OSI layers.
Which OSI model layer has data encryption?
Presentation
What is the Application layer of the OSI model?
Where users interact with the GUI and Network devices.
What important protocol can you find in the application layer?
DNS
What are packets?
A packet holds a frame, which holds data.
What are frames?
An “envelope” holds data.
What is a good metaphor that explains the relationship between packets and frames?
An envelope inside an envelope which holds a letter. The envelope that holds frames are called packets, and the envelope inside the envelope holding data is a frame.
At the data link layer, is there a frame or packet?
Frame
What is the name of a piece of data that has IP Addressing?
Packet
What is the name for a piece of data that doesn’t have IP Addressing?
Frame
What is a colloquial term for TCP/IP
The Three Way Handshake
What is TCP?
Transmission Control Protocol
What is similar to TCP?
OSI Model
What are TCP and OSI?
Systems of rules for networking (connecting devices).
What are the layers of TCP/IP?
1) Application
2) Transport
3) Internet
4) Network Interface
Are packet structures always the same?
No, the structure depends on its purpose.
What also occurs in TCP/IP as in OSI?
Encapsulation
What is the reverse of encapsulation?
Decapsulation
What is the defining feature of TCP/IP?
It’s connection-based
What is the typical structure of a Packet?
Divided into headers; packets added through encapsulation.
What is the structure of an IP packet?
Time to live
Checksum
Source Address
Destination Address
What is “Time to Live” in IP packet structure?
Expiry timer in the event packets do not reach destination or abort
What is “Checksum” in IP packet structure?
Integrity checking protocol that checks for correct values and data corruption in data transmission.
What is “Source Address” in IP packet structure?
The IP address of the device that the packet is being sent from so that data knows where to return to.
What is “Destination Address” in IP Packet structure?
The device’s IP address the packet is being sent to so that data knows where to travel next.
What is the structure of a TCP packet?
Source port
Destination port
Source IP
Destination IP
Sequence Number
Ack number
Checksum
Data
Flag
What are the steps of the 3 way handshake?
SYN
SYN/ACK
ACK
DATA
FIN
RST
What is a SYN transmission?
SYN=SYNchronise
A packet
A SYN message is the initial packet sent by a client during the handshake. This packet is used to initiate a connection and synchronise the two devices together.
What is an SYN/ACK transmission?
A packet. This packet is sent by the receiving device (server) to acknowledge the synchronisation attempt from the client.
What is an ACK transmission?
The acknowledgement packet can be used by either the client or server to acknowledge that a series of messages/packets have been successfully received.
What is a DATA transmission?
Once a connection has been established, data (such as bytes of a file) is sent via the “DATA” message.
What is the FIN transmission?
This packet is used to close the connection after it has been complete.
What is the RST transmission?
This packet abruptly ends all communication if there are errors.
What is any sent data given?
A random number sequence.
What is ISN in TCP/IP? What is it used for?
Initial Sequence Number
Ensuring the correct order of data transmission
Does the 3 way handshake occur in UDP?
No, it doesn’t require a stable connection.
What is the structure of a UDP packet?
Time To Live (TTL)
Source Address
Destination Address
Source Port
Destination Port
Data
Why type of connection is UDP?
Stateless
Why are ports essential?
They are where data is exhanged.
What is the numerical range for ports?
0-65535
Where is all web browser data sent?
Port 80
What is a common port?
0-1024
What is FTP?
File Transfer Protocol
This protocol is used by a file-sharing application built on a client-server model, meaning you can download files from a central location.
What port is FTP allocated to?
Port 21
What is SSH?
Secure Shell
This protocol is used to securely login to systems via a text-based interface for management.
What port is HTTP allocated to?
80
What is HTTP?
HyperText Transfer Protocol
This protocol powers the World Wide Web (WWW)! Your browser uses this to download text, images and videos of web pages.
What is HTTPS?
HypterText Transfer Protocol Secure
Same as HTTP, but in a secure way using encryption.
What port is HTTPS allocated to?
443
What is SMB?
Server Message Block
This protocol is similar to the File Transfer Protocol (FTP); however, as well as files, SMB allows you to share devices like printers.
What port is SMB allocated to?
445
What is RDP?
Remote Desktop Protocol
This protocol is a secure means of logging in to a system using a visual desktop interface (as opposed to the text-based limitations of the SSH protocol).
What is port forwarding?
How applications and services connect to devices outside their direct network.
What is a firewall?
A device that restricts traffic in a port.
What forms can a firewall take?
Large pieces of hardware, residential router or a software.
What are the categories of firewalls?
Stateful
Stateless
What is a Stateful firewall?
Observes entire connection behaviour
What is a Stateless firewall?
Analyses individual packets
What is a VPN?
Virtual Private Network
A program that makes devices from different networks connect and communicate securely.
What are the 2 main benefits of VPNs?
Privacy
Anonymity
How does TryHackMe connect you to their vulnerable machines without making them accesible by the internet and having users breach agreements with their ISPs?
VPN
What are some technologies that VPNs use?
PTTP
PPP
IPSec
What is PPTP?
Point to Point Tunneling Protocol
Allows data encrypted by PPP to be routed.
What is PPP?
Point to Point Protocol
Unroutable tech that authenticates and encrypts data.
What is IPSec?
Internet Protocol Security
Encrypts data using IP framework.
What is a Layer 2 Switch?
Only operates at Layer 2 and only sends frames to devices on its network using MAC Addresses.
What is a Layer 3 Switch?
Can send frames to devices on its network and use IP to send packets to devices outside its direct network.
What is VLAN?
Virtual Local Area Network
Segregates LANs to improve security
Example: creating 2 different IP Addresses for 2 different departments in a Business network.
