2150 Chapters 9,

TCP three way handshake

1. Establishes that the destination device is present on the network 2. Verifies that the destination device has an active service and is accepting requests on the destination port number that the initiating client intends to use 3. Informs the destination device that the source client intends to establish a communication session on that port number

Dynamic or Private Ports (Numbers 49152 to 65535)

Also known as ephemeral ports, these are usually assigned dynamically by the client's OS when a connection to a service is initiated. The dynamic port is then used to identify the client application during communication.

DHCP Server

Assigns an IP address , subnet mask, default gateway and other info to clients

Applications that use UDP

DHCP, DNS, SNMP, TFTP, VoIP , IPTV -Live video and multimedia applications. -Simple request and reply applications -Applications that handle reliability themselves Unidirectional

Features of UDP

Data is reconstructed in the order it is received, any segments lost aren't resent , no session establishment , Does not inform sender about resource availability.

Features of TCP include

Establishing a Session , Reliable Delivery , Same-Order Delivery , Flow Control

_______ helps maintain the reliability of TCP transmission by adjusting the rate of data flow between source and destination for a given session.

Flow Control

Applications that use TCP

HTTP , FTP , SMTP , Telnet ,

Whats TCP's functions?

Numbering and tracking data segments transmitted to a specific host from a specific application* Acknowledging received data* Retransmitting any unacknowledged data after a certain period of time*

Without _________ , the data network would not have a common way to format and direct data.

Protocols

The combination of the source IP address and source port number, or the destination IP address and destination port number is known as a _____.

Socket -socket is used to identify the server and service being requested by the client.

Example of Network applications includes

Some end-user applications are network-aware, meaning that they implement application layer protocols and are able to communicate directly with the lower layers of the protocol stack. Email clients and web browsers are examples of this type of application.

TCP connection establishment includes

Step 1 - The initiating client requests a client-to-server communication session with the server. Step 2 - The server acknowledges the client-to-server communication session and requests a server-to-client communication session. Step 3 - The initiating client acknowledges the server-to-client communication session.

To terminate a TCP connection

Step 1 - When the client has no more data to send in the stream, it sends a segment with the FIN flag set. Step 2 - The server sends an ACK to acknowledge the receipt of the FIN to terminate the session from client to server. Step 3 - The server sends a FIN to the client to terminate the server-to-client session. Step 4 - The client responds with an ACK to acknowledge the FIN from the server.

applications such as databases, web browsers, and email clients, require that all data that is sent arrives at the destination in its original condition. Any missing data could cause a corrupt communication that is either incomplete or unreadable. These applications are designed to use ______ .

TCP

Destination Port

The client places a destination port number in the segment to tell the destination server what service is being requested

Well-known Ports (Numbers 0 to 1023)

These numbers are reserved for services and applications. They are commonly used for applications such as web browsers, email clients, and remote access clients.

Registered Ports (Numbers 1024 to 49151)

These port numbers are assigned by IANA to a requesting entity to use with specific processes or applications. These processes are primarily individual applications that a user has chosen to install, rather than common applications that would receive a well-known port number. ex:Cisco has registered port 1985 for its Hot Standby Routing Protocol (HSRP) process.

Sockets enable multiple processes, running on a client, to distinguish themselves from each other, and multiple connections to a server process to be distinguished from each other. (T/F)

True

The destination port number is associated with the destination application on the remote host. (T/F)

True

The source port number is associated with the originating application on the local host. (T/F)

True

The window size is the number of bytes that the destination device of a TCP session can accept and process at one time. (T/F)

True

TCP is a connection-oriented protocol. (T/F)

True -A connection-oriented protocol is one that negotiates and establishes a permanent connection (or session) between source and destination devices prior to forwarding any traffic.

_____ is a stateless protocol, meaning neither the client, nor the server, is obligated to keep track of the state of the communication session.

UDP

_____ is similar to placing a regular, non-registered, letter in the mail. The sender of the letter is not aware of the availability of the receiver to receive the letter. Nor is the post office responsible for tracking the letter or informing the sender if the letter does not arrive at the final destination.

UDP

_______ has much lower overhead than TCP because it is not connection-oriented and does not offer the sophisticated retransmission, sequencing, and flow control mechanisms that provide reliability.

UDP

_____ is preferable for applications such as streaming live audio, live video, and Voice over IP (VoIP). Acknowledgments and retransmission would slow down delivery.

UDP -an application can tolerate some data loss during transmission over the network, but delays in transmission are unacceptable. UDP is the better choice for these applications because less network overhead is required.

Whats UDP do?

UDP provides the basic functions for delivering data segments between the appropriate applications, with very little overhead and data checking. UDP is known as a best-effort delivery protocol.

Email Server

Uses Simple Mail Transfer Protocol (SMTP) , Post Office Protocol (POP3) , or Internet Message Access Protocol (IMAP)

FTP Server

allow for upload and download of files between a client and a server

SSH Server

allows administrators to log in to a host from a remote location and control the host as though they were logged in locally

Source Port

is dynamically generated by the sending device to identify a conversation between two devices. -Each separate HTTP conversation is tracked based on the source ports.

the ______ command will attempt to resolve IP addresses to domain names and port numbers to well-known applications. The -n option can be used to display IP addresses and port numbers in their numerical form.

netstat

Domain Name Server (DNS)

service that provides the ip address of a website or domain name so a host can connect to it

whats a socket

the combination of a source IP address and port number or a destination IP address and port number*

What is the purpose of the network security authentication function?

to require users to prove who they are

Web Server

uses HTTP , transfers data between web clients and web servers