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ANALYSIS PACKAGE USING THE TRANSPORT LAYER WIRESHARK

Basic theory

Transport layer, Functioning responsible for communicating between the host / computer. In this layer can be selected if using a protocol that supports error-recovery or not. Performs multiplexing of the data coming in, sort the data that came when the arrival is not sequential.

In this layer also the communication from end to end (end-to-end) arranged in several ways, so that business data is heavily influenced by this fourth layer. In this layer known as the port number. Port number associated with the application being run. In addition to known socket port number that is a combination of the IP and the type of protocol used is TCP or UDP.

TCP (Transmission Control Protocol)

Transmission Control Protocol (TCP) is one of the protocols at the Transport layer that provides data transmission function connectionoriented. For this purpose TCP provides control of data flow (flow control), by means of sliding windows. Referred to as reliable TCP protocol (a protocol that can be trusted) by providing a sequence number and acknowledgment. And also. by way of prevention of duplication of data, congestion control and flow control.

TCP format can be seen in Figure below.

UDP (User Datagram Protocol)

User Datagram Protocol (UDP) is one of the protocols at the Transport layer that provides functionality that provides connectionless delivery function, the path is not reliable. UDP does not have the function of data reliability, flow control, and errorrecovery for IP communications. UDP is widely used in applications that require high speed and can metoleransi against data loss.

UDP format can be seen in Figure below.

Practice

Work in groups with your friends, at least two people.

On one computer Make sure telnet and ftp are already installed on the computer one of the computers in the group. If you have not done the installation. How to install telnet sudo apt-get install openbsd-inetd

Sudo /etc/init.d/openbsd-inetd restart

How to install ftp server sudo apt-get install proftpd-basic

On the other computer Make sure Wireshark is installed on the computer that will contact the computers installed telnet and ftp. Launch Wireshark. #sudo wireshark

Then click the Interface List, then a new window will appear as shown below:

This is a description of flags in the TCP in Wireshark.

Flag URG (urgent) serves to identify that part of the TCP that contains data that is very important.

Flag ACK (acknowledgment) function to determine whether the transmitted data has been received or not on the client computer

Flag PSH (push) function to indicate the contents of the received TCP PSH dikomputer client.jika worth 1 then the data should not be one byte is gone, if it is lost then the data will be resubmitted.

Flag RST (reset) is used to identify the connection will fail their made a TCP connection is currently running (active), a segment with the RST flag set to a value of 1 will be sent in response to a received TCP segment that turns that segment is not the requested, so the connection was to fail

SYN flag serves to indicate that the corresponding TCP segment contains the Initial Sequence Number (ISN). During the manufacturing process the TCP connection session, if it did request it will give valuable SYN 1

FIN flag serves to indicate that the sender of a TCP segment has been completed in sending data in a TCP connection. When a TCP connection is finally terminated (as a result there is no data to be sent again), each host TCP sends a TCP segment with the FIN flag set to a value of 1.

Next run telnet to get to a computer installed telnet. Have

user and password from a computer that is telnetnya.

# Telnet no_ip_komputer_telnet

After the reboot process laukan

Questions and Tasks

Give the conclusion of lab work you are doing !!! We can make the process of communication between the host / computer. Then can melakuakn multiplexing the data came, sort the data that came when the arrival is not sequential.

What is the use of TCP transport type ??? Multiplexing, Doing segmentation process and reunite the segmented data (reasembling) from the upper layer to the data flow, service provides transport of data from end to end, Responsible for providing a mechanism multiplexing (multiplexing is a technique delivery and menerimaan data that have different types in the same time), the locus of the 3-way hand shake

In what circumstances we need a transport layer connection using UDP type ??? In applications that require high speed and can tolerate the destruction of data.

Find information on the internet about the speed of TCP and UDP as well as the usefulness of each type of the transport layer !!!

Data transfer speed: transfer speed on TCP slower than UDP.

UDP is faster because it does not check the package error

The usefulness of each layer TCP

Physical Layer (physical layer) is the lowest layer that defines the physical quantity such as a communication medium, voltage, current, etc.

This layer can vary depending on media communications on a network bersangkutan.TCP / IP is flexible so that it can integrate various networks with physical media is different.

Network Access Layer have similar functions to the Data Link layer of the OSI. This layer regulate the distribution of data frames of data on physical media used reliably. This layer usually provides services for detection and error correction of the transmitted data. Some examples of protocols used at this layer is the public network X.25, Ethernet for networking Etehernet, AX.25 network etc. Package Radio.

Internet Layer defines how the relationship can take place between the two parties are on different networks such as the Network Layer of the OSI. On the Internet network consisting of tens of millions of hosts and hundreds of thousands of local network, this layer duty to ensure that a package sent to find its purpose regardless of location. Therefore, this layer has a particularly important role in realizing the internetworking covering large areas (worldwide Internet). Some of the important task at this layer are: Addressing, which complement each datagram with the Internet address of the destination. The address on this protocol known as Internet Protocol Address (IP Address). Because addressing (addressing) on a TCP / IP network is at this level (software), then the TCP / IP network independent of the type of media and computer used.

Routing, which determines where the datagram will be sent in order to achieve the desired objectives. This function is the most important function of the Internet Protocol (IP). As a connectionless protocol, the routing process is completely determined by the network. The sender does not have control over it sends packets to reach the goal. Routers on the network TCP / IP was crucial in the delivery of the datagram to the destination receiver.

Transport Layer defines ways for data transmission between the end-to-end host reliably. This layer ensures that the information received on the receiver side is the same as the information sent to the sender. To that end, this layer has several important functions, among others:

Flow Control. Delivery of data that have been broken down into packets must be arranged in such a way that the sender not to send data at a rate that exceeds the ability of the recipient to receive the data.

Error Detection. Senders and recipients also supplement the data with the amount of information that can be used to examine data transmitted error free. If errors are found in the data packet is received, the recipient will not receive the data. The sender will resend data packets that contain errors earlier. However, this can cause a significant delay.

Application Layer is the last layer in the architecture of TCP / IP that serves to define the applications that run on the network. Therefore, there are many protocols in this layer, in accordance with the number of TCP / IP applications that can be run. An example is SMTP (Simple Mail Transfer Protocol) for sending e-mail, FTP (File Transfer Protocol) for file transfers, HTTP (Hyper Text Transfer Protocol) for Web applications, NNTP (Network News Transfer Protocol) for the distribution of news and so on other. Each application generally uses the TCP and IP protocols, so that the whole family is named after the protocol with TCP / IP.

The usefulness of each layer UDP

Both TCP and UDP use the same IP _rotocol layer 3 TCP and UDP primarily used for diverse applications. TCP serves applications such as FTP, HTTP, SMTP and DNS. While UDP is _rotocol layer 4 is used by DNS, TFTP, SNMP and DHCP.

Protocols were "mild" (lightweight): To conserve memory and processor resources, some application layer protocols require the use of a lightweight protocol that can perform specific functions by exchanging messages. An example of a lightweight protocol is the query function in the application layer protocol name Domain Name System.

Application layer protocol that implements reliability services: If the application layer protocols provide reliable data transfer, the need for reliability offered by TCP became no. Examples of such protocols are the Trivial File Transfer Protocol (TFTP) and Network File System (NFS)

Protocols that do not require reliability. Examples of this protocol is a protocol Routing Information Protocol (RIP).

Transmission broadcast: Because UDP is a protocol that does not need to make a connection first with a particular host, the broadcast transmission was possible. An application-layer protocol can send data packets to multiple destinations using multicast or broadcast address. This contrasts with the TCP protocol transmission can only transmit one-to-one. Example: query names in the NetBIOS Name Service protocol.

Mention some of the usual applications using TCP and specify the type of applications that commonly use UDP ???

Some applications that use TCP are:

Web Browser, E-mail, file transfer, etc.

Some applications that use UDP are:

Domain Name System (DNS), Video Streaming, Voice over IP (VoIP), etc.

Mention some of the existing requirements on the type of communication using TCP at the transport layer ???

if the user wants to send data must initialize the connection and get recognition or acknowledgment from the receiving party. And after obtain recognition, the recognition mangakui sender, thus completing the process of a three way handshake. So after all that is done TCP can make a connection.

What is called the three way handshake, what is the relationship with the TCP ???

that each connection it must be prepared in advance before data transfer begins. This synchronization process assures kedu side is ready transmitting any data yet and allows the device to determine the initial sequence number. Phase one, the client sends a packet synchronization (SYN flag set) to initialize the connection. Packages considered valid if niali sequence numbernya eg x. SYN bit indicates a connection request. SYN bit length of the bits of the TCP header segment. And a sequence number 32 bits in length. Phase two, the other host receives the packet and record the sequence number x from clients and reply with the acknowledgment (ACK flag set).

ACK control bit indicates bahwaacknowledgement acknowledgment number contains a valid value. ACK flag the length of Ack bit and 32 bit number in the TCP segment header. Once a connection is established, ACK flag is set for all segments. ACK number value to x + 1 means the host has received all bytes including x and add the next reception x + 1. Phase three, the client responds with Ack Number y + 1, which means he received the ack before and terminate the connection process for this session.

What is also called flow control ???

Flow Control, the limited amount of memory on the computer, and without flow control a larger computer might flood a computer with so much information that can not hold it all before dealing with it. Currently, this is not a big problem, because the cost of memory bandwidth while relatively expensive, but in earlier times it is more important. Flow control allows the receiver to say ³Whoa! 'Before overwhelmed. Sometimes this has been provided by the network, but where it is not, the Transport layer can be added in the byte orientation. Instead of dealing with things in a package-by-package, the Transport layer may add the ability to view communication just as a stream of bytes. It is better to deal with.

Conclusion

The transport layer is the level four of the seven levels of the OSI model. In response to a service request from the session layer and issues service requests to the network layer.

Transport Layer assigned to conduct communication sessions between computers in a network. Menenrukan how data is transmitted.

Two Transport Layer Protocol used:

Transmission Control Protocol (TCP)

User Datagram Protocol (UDP).

User Datagram Protocol

UDP is a connectionless communication, work does not guarantee the data arrived at the destination as a whole.

Normally for transmitting small amounts of data at one time.

Reliability / assurance of data arrive at the receiver depending on the application.

Transmission Control Protocol (TCP)

Connection-oriented and reliable communication which means the data is guaranteed to destination

To guarantee the required initial communication with the receiver before the data transfer

do

Requires ack every reception of data Used to transmit large amounts of data