2.1 - 2.2 Networking Protocols and Hardware Flashcards
What are the five parts of (IP) Internet Protocol?
Ethernet header (client)
IP (internet protocol)
TCP (transmission control protocol)
HTTP data
Ethernet trailer (server)
What’s the difference between TCP and UDP?
TCP (transmission control protocol) is a connection-based protocol. It’s reliable, so it can reorder data, conduct retransmissions, and manage data limits.
UDP (user datagram protocol) is a connectionless protocol. It’s unreliable, meaning it has no error recovery or receipt of data sending. No flow control
What is multiplexing?
Uses both TCP and UDP to transmit data for many different applications at the same time
DHCP and TFTP are examples of: TCP or UDP? What do they stand for?
UDP
Dynamic Host Configuration Protocol
Trivial file transfer protocol
Protocols like HTTP and HTTPS are examples of: UDP or TCP?
TCP. They require a return receipt
What is a port number?
It’s written on the outside of a packet to ensure that the contents get to the right application
What are the parts of an IPv4 packet?
Server IP address, protocol, server application port number
Client IP address, protocol, client port number
What are non-ephemeral ports?
Permanent port numbers usually on a server or service. Usually go from 0 to 1023. Ex, port 80 = HTTP, port 443 = HTTPS
What are ephemeral ports?
Temporary port numbers that are determined in real-time by the client. Usually between 1024 and 65,535
Why is it important that port numbers should be well known numbers?
Port numbers are for communication, not security. This prevents us from having another system to create / decode port numbers, which would complicate communication
What is TCP port 20 / 21?
20 = data transfer port in FTP (file transfer protocol)
Authenticates with a username and a password
Can add / delete / transfer files
What is TCP port 21?
21 = default port used for control channel in FTP (file transfer protocol)
What is TCP port 22?
SSH (secure shell)
Encrypted communication link
Connects you to a remote device through command line
What is TCP port 23 and when would you use it?
Telnet (telecommunication network protocol)
Lets us connect to a device remotely
This information is not encrypted, so be wary of using Telnet on production systems
What is TCP port 25 and when would you use it?
SMTP (simple mail transfer protocol)
Used to send email (not usually to receive)
Server to server email transfer
Device to server email transfer
What is UDP port 53 and when would you use it?
DNS (domain name system)
Converts names to IP addresses
What is UDP port 67?
Used by DHCP servers to communicate with clients on a network
Uses a leasing system
Able to reserve static IP addresses (admins, etc.)
What is UDP port 68?
Used by DHCP servers to respond to messages
What is TCP port 80 / 443 and when are they used?
Port 80 = HTTP (hypertext transfer protocol)
Port 443 = HTTPS (hypertext transfer protocol secure)
Which one you’re using depends on whether you’re connecting to the web with encryption (HTTPS) or in-the-clear (HTTP)