UNIT- 5

·       File Transfer Protocol (FTP) – one of the most popular uses of internet is to download file, transfer file from one computer on the internet to your computer. Thousands of files are downloaded every day on the internet. Most of these files are downloading using the file transfer protocol known as FTP.  This protocol can also be used to upload files from your computer to another computer on the internet. FTP is an client that comes with windows NT’s is a character based client. Numerous FTP servers all over the world allow user to log in and download files from internet. The main completers for FTP are Hyper Text Transfer Protocol. Because HTTP server’s can do whatever FTP server can do and more efficiently. FTP executes on the top of TCP/IP’s Stac and uses the OSI protocol to enable users and application to transfer file among network stations.

Ø Antivirus – You can access file from the internet but, downloaded internet files are the principal source of entry for computer viruses. Therefore you must protect your network against those download viruses . for this purpose we use antivirus. There are many website for excess Macfee website is not the only place where you can get free antivirus programs. But you can but it to get more features like online help and regular update.

1.  Shareware – shareware is the software that is distributed for free on a trial basics. If you like the software and you want to continue to use it beyond its trial period it is your responsibility to register and pay for it

2.  Free ware – software distributed absolutely free is called freeware .

3.  Nagware - software that reminds you to registers all the time is often called nagware.

·       FTP  servers – Similar to the web server the internet also has the FTP server. Many organization use FTP server to handle the distribution of files. When a user link to download some thing the link actually redirect to FTP. Some file in the FTP servers may be accessible to general public while others are accessible only by the registered user. FTP servers are divided into two parts.

1. Anonymous server

2. Non anonymous server

                                                      I.            Anonymous server- anonymous server is the most common use of ftp. ftp sites that allows anonymous ftp do not required a password for access. You only have to log in as anonymous and enter email address as password

                                                   II.            Non anonymous server-  if you use a non-anonymous server than you will log in as yourself and give your password.

·       FTP clients- FTP runs on a client server model for using ftp you will need client software to run your p.c. To begin an ftp section you run the ftp software and connect to the ftp server from where you want to download file you can use client software available in windows NT. The ftp client talks to a ftp server. Ftp uses TCP to handle communications and create a session between the hosts. When you log on to the ftp server a connection called a command linked is open between you computer and the server. This link is used for sending commands to the server form your computer and sending message and information back from the server to compete when you issue a command to download a file  a second so connection open up for called data command and also called data link. This command can be opened up in one of the following modes

                                                      I.            ASCII MODE – the ASCII mode is used for sending text fill and alters things such as the feed and carriage .

                                                   II.            THE BIANY MODE – the binary mode is used for sending binary files and lets file through untouched

                                                III.            Line mode- line mode ftp is use to send text file line by line or it is similar to ASCII mode but with additional features.

·       Connection With FTP – to connect to an ftp site you need to know the name of an account on the ftp server. In other words you need to log in with user name and password so that the server know who you are. Publically accessible ftp site expect to you to use a special account called anonymous to connect to an ftp site do following steps

                                                      I.            Enter the URL of ftp site in the address box and click go. For example to connect to ftp site write the URL ftp://

                                                   II.            Browser opens the specified site

                                                III.            Display the directory that contains the file you want to download.

                                                IV.            Right click the file and choose copy to folder

                                                   V.            Once you have saved the file in your computer drive. You can open it using the appropriate software depending upon the type of file.

·       Different type of FTP clients –

1.  Browser based ftp clients- ftp with internet explorer – Microsoft internet explorer ftp interfaced is basic on the ordinary windows explorer folder which make  remote file access as easy as accessing folder as on your computer . follow these simple step to make and ftp connection with internet explorer.

                                                      I.            Active internet explorer by clinking its desktop shortcut.

                                                   II.            Connect to a site directly by entering its address in the address box.

                                                III.            To navigate the ftp site click folder can to open sub directory.

                                                IV.            Click on files to download them.

                                                   V.            Save them into your computer drive.

                                                VI.            Exist internet form internet from internet form internet explorer.

2.  FTP with NETSCAPE navigator – NETSCAPE navigator has similar ftp features as an internet explorers. Here are following steps to connect with ftp sits using Netscape navigator

                                                            i.      Launch NETSCAPE navigator by click on desktop shortcut.

                                                         ii.      connect to site by entering its address in the address box.

                                                      iii.      click on files to download them you can also upload file simply drag a file into the browser windows and click yes to upload it and close the navigator.

Ø TELNET-telecommunication network – it is a virtual terminal protocol allowing a user logged on to a tcp ip host to access other host on the network. You can access many host on the internet by using telnet. Host is all different computers.

Ø Establishing telnet connection – to use telnet you need know the address of the host whose resources you want to use. Your telnet client contact the host using its internet addresses. When you connect the host, the distant computer and your computer negotiate how they will communicate with each other. They decide which terminal emulation will be used .Telnet emulation determines .how you keyboard will transmit information to the distant computer and how information will be displayed on your screen. For example it determines how a backspace key will work. Type text in a telnet section accumulates in a buffer on your computer. When a complete line of data is ready for transmission or when you give a command to transmit data the data is send across the internet from your network virtual terminal keyboard. Along with the data host’s ip address which make sure that the packet is send to proper location also sent

Ø Connecting to a remote host- following these steps are use to connect to a remote host using telephone

1.   Open telnet for this. Go to the start menu and choose run. Type telnet and press enter key.

2.   From the menu choose connect the choose remote system.

3.   Enter the name of IP address of the system that you want to connect to in the host name filed

4.   It required specifying a port in the port filed.

5.   In the term type select the type of terminal that you want telnet to emulate

6.   After you are finished with the remote host you can disconnect from a remote host by choosing.

Ø Characteristics of telnet- there are following characteristics of telnet

1.   Telnet is the terminal emulation protocols when you start installing and configuring tcp ip device you are going to need some way to connect to the device to issue its commands

2.   Telnet is versatile- you a establish telnet session over the phone. If there is not phone connection and your device is accessible to the internet you can establish a telnet over the internet.

User authentication -one of important features of the internet is that it lets you access the distant computer somewhere located in the world. Firmware office or homeware can log into another computer and access to all of its resources. This operation is done by telnet. To use telnet you must know the address of the internet host how’s resources you want to access and then you have to log on to the host.

Mostly guest is used for log in but some systems may also require additional information such as name address some systems require username and password. When you connect using telnet you have to use terminal emulation. That decide you should make sure your keyboard a monitor function as the host expects.
Ø Client server model – the client server model describes how a server provides resources and services to one or more clients. Example of server includes web server, mail server, file server. Each of these server provide resources to client devices such as desktop computer, laptops , tablets , smart phones etc. most servers have a one to many relationship with clients which means a single server can provide resources to multiple clients at a one time. When a client request a connection to a server the server can either accept or reject the connection. If the connections accepted the server establish and maintained a connection with the client over a specific protocol. For example as email client may request and SMTP Connection to a mail server in order to send a message. The SMTP application on the mail server will them request auth from the client such as the email address and password. If all the details match an account on the mail server. The server will send the email to the intended recipient.

Client server model where individual clients request services and resources from centralized server.

PEER to PEER (P2P) Network Model- in a P2P network the peer’s are computer systems which are connected to each other via the internet. Files can be shared directly between systems on the network without need of a central server. In other words each computer on a P2P network becomes a file server as well as a client. the only requirement for a computer to join a PEER to PEER network are an internet connection and P2P software  common P2P software programs are KAZAA, LIMEWIRE , BEARSHARE etc. these program connect to a P2P network  which allows the computer to access thousands of other systems on the networks.

Once connected to network P2P software allows searching for files on others computers. Meanwhile other users on the network can search for files on your computer but typically only within a single folder that you have designated to share. While P2P networking make files sharing easy and convenient is also has led to allots of software piracy and it large music download.

PEER to PEER network in which interconnected nodes share resource among each other without the use of a centralized server.