9.4 The Transmission Control Protocol - internet protocol (TCP IP) Flashcards
What does TCP / IP stand for?
Transmission control protocol / internet protocol.
What is TCP / IP?
A protocol that is used in all parts of the internet to enable different devices to communicate.
What are the 4 layers in the TCP / IP stack?
Application, transport, network, link
What is the role of the application layer in the TCP / IP protocol?
Selects and uses the correct protocol to transmit data. The layer interacts with the user with application software like a web browser.
What is the role of the transport layer in the TCP / IP protocol?
Establishes a virtual path between the sender and the receiver. Splits the transmission into packets. Each packet has a sequence number which identifies a packet’s position in relation to other packets that form part of the same message. They also contain the port number to be used which identifies the protocol in use.
What is the role of the network layer in the TCP / IP protocol?
Provides the correct IP addresses for each packet’s source and destination. Routers work within this layer, using the IP addresses on a packet to send it to its destination.
What is the role of the link layer in the TCP / IP protocol?
Controls physical connections between pieces of hardware in a network. Adds MAC addresses to packets which it receives from the network layer. MAC addresses change with every hop through a network
How does the TCP / IP protocol work at the receiving end?
Once a packet has been received by its recipient it is stripped of its extra information by reversing the TEP / IP stack.
What is the role of the link layer in the receiving end of TCP / IP protocol?
Removes MAC addresses from the packet
What is the role of the network layer in the receiving end of TCP / IP protocol?
Removes IP adresses
What is the role of the transport layer in the receiving end of TCP / IP protocol?
Uses the packet’s port number to determine the correct application to send the packet to. It also uses the packet’s sequence number to ensure that it is in the correct position relative to other packets in the same transmission.
What is the role of the application layer in the receiving end of TCP / IP protocol?
Receives the packets and displays the information to the user accordingly
What is a socket address?
When an IP address is combined with a port number.
What does a socket address do?
Identifies which of the applications on the recipient device a packet should be sent to.
What port(s) does the FTP (file transfer protocol) use?
20 and 21
what port(s) does the SSH (secure shell) use?
22
What port(s) does the HTTP (Hypertext transfer protocol) use?
80
What port(s) does the HTTPS (hypertext transfer protocol secure) use?
443
What port(s) does POP3 (post office protocol 3) use?
110 & 995
what port(s) does SMTP (simple mail transfer protocol) use?
25, 587 & 465
What is the purpose of FTP (file transfer protocol)?
Sending files between devices
Clients can access FTP servers
anonymously or non anonymously
What is the purpose of SSH (secure shell)?
Remote management of computers
Requires a username / password combination
Encrypts information during transmission
How does SSH (secure shell) work?
In order to access a remote computer SSH requires a username / password combination and encrypts information during transmission. SSH clients are pieces of software which can be used to make a TCP connection to a remote port. Once connection is established commands for application level protocols can be sent to the remote computer.
What is the purpose of HTTP (Hypertext transfer protocol)?
Sending web pages in text form from web