Ports And Protocols Flashcards
Was is a Port?
Virtual entry/Exit Point for communications used by Software applications to Exchange information
What is a protocol?
Set of rules, conventions for data exchange between nw devices
Nw Port Fundamentals, Port?
logical opening in computer
identify specific applications/services on computer that represents service/application
0 to 65535
IP address
diect data to correct system in nw
Three group of ports, well-known ports (5 points)
0-1023
FTP(20,21)
SMTP(25)
HTTP(80)
HTTPS(443)
Three group of ports, registered ports 1 point
1024-49151
Three group of ports, ephemeral(very short time period) Ports (3 points)
short-lived ports, dynamic use
49152-65535
No registration required anyone can use them
what does IANA stand for
Internet Assigned Numbers Authority
Data transfer example (2 points)
client communicates with website using ip address + port
clients source ip + random ephemeral port connect websites dest ip and default port (e. g. 80)
Two Way Communication 2 points
Web server responds using well-known port (80) back to the clients ephermeral port
Two-way com. established client (ephermeral port) <=> web server (80
3 more detail about nw fundamentals
ephermeral opens for specific task, closte after data transmission
subsequen com. client uses well-known(80) but select new random ephermeral port
Communication Flow (source ip + port initiate com, data is transmitted, port closed when task completed)
What does TCP stand for?
Transmission Control Protocol (TCP),
4 facts about TCP
fundamental in Internet Protocol Suite, governs data exchange over inet
Ensures reliable delivery of packets (error checking, data sequencing, ack)
Transport Layer (3)
breaks down lager messages into smaller packet for efficient data transfer + reassembles at destination
What is a Three-Way Handshake? (2 points)
initiate to establish a connectgion between two systems:
SYN (Synchronize)
SYN-ACK (Synchronize-Acknowledgement)
ACK(Acknowledgement)
Ensures readiness for secure data transmission
TCP Error Checking and Flow Control (2 points)
Error Chcking and Flow Control:
Use sequence numbers and ack messages
detects and retransmits lost or corrupted packets
Flow control:
prevents overwhelming the receiver
Windowing (Controls the amount of data sent at a time, allows dynamic adjustment based on nw conditions)
What are TCP Ports? (4 points)
Numerical identifiers for services or apps in TCP/IP suite
Distinguish between different services on same server
Each connection identified by source and dest ip addresses + ports (e. g. secure websites uses port 443 HTTPS)
Enable multiple nw applications on the same server
TCPs role in Internet Communication (5 points)
Ensures reliability + ordered delivery between client and server
Operates transport layer of the OSI model (layer 4)
Utilizes packetization, ack and error checking
Three-way handshake establishes secure conn
Ports facilitate logical differentiation of services on single machine
User Datagram Protocol (UDP), what is UDP, what is it good for (3 points)
Communication protocol used for time-sensitive transmissions on internet (ideal for apps prioritizing speed over error checking, low latency and reduced processin overhead, lacks error checking + recovery services like TCP
Operates at the transport layer ,similar to TCP
Connectionless communication model
What is UDPs Packet Structure? (1 point, 4 sub-points)
Datagram:
Term for data packet in UDP
Sent without prior setup of transmission channels
Contains source/destination port numbers, length field, and checksum
Smaller and simpler header (8 bytes) compared to TCP (20-60) bytes
What is UDPs Stateless Nature? ( 3 points)
UDP does not maintain conn state or track packets
Often referred to as a “fire and forget” protocol
No waiting for ack, leading -> faster transfer rates
Reliability Trade-off UDP? (2 points)
UDP is less reliable due to lack of packets tracking
Suitable for scenarios where speed is crucial, and packet loss is acceptable
Use Cases UDP
Used in apps like live broadcasts, online gaming and VoIP calls
Effective for simple request-response comm (e.g DNS lookup)
What does UPD utilizes?
Ports to differntiate between multiple services on the same client/server
What does UDP rely on?
application-level error handling due to lack of built-in error recovery