File Transfer Protocol
File Transfer Protocol
FTP is short of File Transfer Protocol, it is a standard Internet protocol for transmitting or exchanging files between computers on the Internet. Like the Hypertext Transfer Protocol (HTTP), which transfers displayable Web pages and related files, and the Simple Mail Transfer Protocol (SMTP), which transfers e-mail, FTP is an application protocol that uses the Internet’s TCP/IP protocols to enable data transfer. FTP is commonly used to transfer Web page files from their creator to the computer that acts as their server for everyone on the Internet. It’s also commonly used to download programs and other files to your computer from other servers. FTP is a protocol through which internet users can upload files from their computers to a website or download files from a website to their PCs. Originated by Abhay Bhushan in 1971 for use in the military and scientific research network known as ARPANET, FTP has evolved into a protocol for far wider applications on the World Wide Web with numerous revisions throughout the years. FTP is the easiest way to transfer files between computers via the internet, and utilizes TCP, transmission control protocol, and IP, internet protocol, systems to perform uploading and downloading tasks. File Transfer Protocol (FTP) is the standard mechanism provided by TCP/IP for copying a file from one host to another. Although transferring files from one system to another seems simple and straightforward, some problems must be dealt with first. For example, two systems may use different file name conventions. Two systems may have different ways to represent text and data. Two systems may have different directory structures. All of these problems have been solved by FTP in a very simple and elegant approach. FTP is most commonly used to download a file from a server using the Internet or to upload a file to a server (e.g., uploading a Web page file to a server). FTP is built on client-server architecture and uses separate control and data connections between the client and the server. FTP works on the client/server principle. A client program enables the user to interact with a server in order to access information and services on the server computer. When downloading a file from the Internet you’re actually transferring the file to your computer from another computer over the Internet. This is why the T (transfer) is in FTP. You may not know where the computer is that the file is coming from but you most likely know it’s URL or Internet address. Files that can be transferred are stored on computers called FTP servers. To access these files, an FTP client program is used. This is an interface that allows the user to locate the file(s) to be transferred and initiate the transfer process. One good reason to use FTP is to download files. FTP is much faster than standard HTTP downloads (through your browser). TCP and IP are the two major protocols that keep the internet running smoothly. TCP manages data transfer while IP directs traffic to internet addresses. FTP is an underling of TCP and transfers or carries files back and forth between FTP server and FTP client. Because FTP requires that two ports be open–the server’s and the client’s–it facilitates the exchange of large files of information. First, you as client make a TCP control connection to the FTP server’s port 21 which will remain open during the transfer process. In response, the FTP server opens a second connection that is the data connection from the server’s port 20 to your computer. Using the standard active mode of FTP, your computer communicates the port number where it will stand by to receive information from the controller and the IP address–internet location–from which or to which you want files to be transferred. If you are using a public or ‘anonymous’ (guest user) FTP server, you will not need proprietary sign-in information to make a file transfer, but you may be asked to enter your email address. If you are using a private FTP server, however, you must sign in with a user name and password to initiate the exchange of data. The most common use of FTP – for data transfer purposes, is of greatest help to users creating their websites on their personal computers due to the high flexibility levels it offers as far as the parameters of the computer-server connection are concerned. FTP comes in handy as soon as the websites’ files are created (via a text editor or a specific webpage program) and are ready to be moved to the server where the websites will be hosted, so that their content could become accessible online. Through an FTP client, users can move their files to the server where their hosting account is located in seconds. Moreover, they can upload as many files at a time as necessary. There are two modes of transfer in FTP: ASCII and Binary.• ASCII is used only for files saved in ASCII format (this includes Postcript files)
• Binary is used for files that are formatted and saved using a word processing software like WordPerfect (.txt), spreadsheets (.xls), images (.jpg, .gif), and many executable programs (.exe) and videos (.avi).
Goals of FTP Service• Promote sharing of files (programs and/or data)
• Encourage indirect/implicit use of remote computers
• Shield users from variations in file storage among hosts
• Transfer data reliably and efficiently
Below figure show that how user who operates on FTP client machine (PC) can communicate with FTP server to transfer files (downloading & uploading) with the help of TCP/IP protocol. The person who creates the FTP sites decides which files to keep locked and which remain public. The virtual ‘key’ to get into an FTP site is the UserID and Password. If the creator of the FTP site is willing to give everyone access to the files, the UserID is ‘anonymous’ and the Password is your e-mail address (e.g.name@domain.com). If the FTP site is not public, there will be a unique UserID and Password for each person who is granted access. When connecting to an FTP site that allows ‘anonymous’ logins, you’re frequently not prompted for a name and password. Hence, when downloading from the Internet, you most likely are using an anonymous FTP login and you don’t even know it. To make an FTP connection you can use a standard Web browser (Internet Explorer, Firefox, etc.) or a dedicated FTP software program, referred to as an FTP ‘Client’. When using a Web browser for an FTP connection, FTP uploads are difficult, or sometimes impossible, and downloads are not protected (not recommended for uploading or downloading large files). When connecting with an FTP Client, uploads and downloads couldn’t be easier, and you have added security and additional features. For one, you’re able to to resume a download that did not successfully finish, which is a very nice feature for people using dial-up connections who frequently loose their Internet connection.
