1.1 Flashcards
What are TCP and UDP encapsulated by?
IP
IP encapsulates what?
TCP and UDP
What are TCP and UDP?
Two ways to move data from a place to another. Different features for different applications.
Which layer handles TCP and UDP in OSI:
Transport, almost all the time when someone is talking about layer 4, they are talking about TCP & UDP
one of the features of using TCP and UDP protocols:
Multiplexing, It allows us to use multiple applications at the same time across the network.
What are TCP and UDP?
one of the protocols in the IP network.
IP:
Internet Protocol
TCP:
Transmission Control Protocol
TCP specifications:
- It is connection oriented (a formal connection setup & close)
- RELIABLE delivery and acknowledgement is sent back (recovery from errors, can manage out of order messages or re-transmissions
- Flow control (Receiver can manage how much data is sent)
UDP:
User Datagram Protocol
UDP specifications:
- Connection-less (no formal open or close to the connection)
- UNRELIABLE delivery, no acknowledgement (No error recovery, No reordering of data or re-transmission)
- No flow control (sender determines the amount of data transmitted)
what decides the form of protocol between TCP and UDP:
application and the way the application works. Not all applications need an acknowledgement for sending data.
T/F) IP delivers data from one IP address to another IP address.
True, every computer has an IP address.
what happens to the data when it gets to receiver:
each part of the data goes to designated port number in the new device.
T/F) We usually don’t associate different port numbers with different applications.
False, that’s why when a data arrives on a new computer, it knows exactly which applicant it is going to.
What kind of ports do we have:
- IPv4 sockets
- non-ephemeral ports
- Ephemeral ports
what information do we need to be able to transfer data over IP sockets:
- a)Server IP address, b)Protocol (TCP/UDP), c)server application port number
- a) Client IP address b) protocol (TCP/UDP)
c) client port number
non-ephemeral ports specifications:
- They have permanent port numbers
- ports are 0 - 1023
- usually on a server or service
Ephemeral ports specifications:
- temporary port numbers
- Ports are 1024 -65535
- Determined in real-time by the client
What port numbers can be used for TCP and what port numbers can be used for UDP:
They both can use any port number between 0 - 65535
T/F) All servers only use non-ephemeral port numbers.
False. Most servers use non-ephemeral port numbers but thats not always the case and it can be different.
can port numbers be used for security:
No, Port numbers are for communication, not security.
why do service/server port numbers need to be WELL KNOWN:
To access a server we need to know the exact port number and to be able to communicate.
T/F) TCP port numbers are the same UDP port number and can have a conflict.
False. each protocol can use the same number as the other one and still no issues. ie, UDP 80 can work for one application and TCP 80 could be used by another application at the same time.
What is the third form of protocol in IP:
ICMP: Internet Control Message Protocol
T/F) ICMP protocol is used for data transfer.
False. Commonly used for:
- administrative functions to check on devices.
- devices can send messages when things don’t go well.
Telnet protocol:
Telecommunication Network (Port: TCP/23)
what is telnet used for:
- Login to devices remotely
- Console access
- In the clear communication
- Not the best choice for production systems
SSH protocol:
Secure Shell (Port: TCP/22)