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The File Transfer Protocol (FTP) is a software standard for transferring computer files between machines with widely different operating systems. It belongs to the application layer of the Internet protocol suite.

FTP is an 8- bit client- server protocol, capable of handling any type of file without further processing, such as MIME or Uuencode. However, FTP has extremely high latency; that is, the time between beginning the request and starting to receive the required data can be quite long, and a sometimes-lengthy login procedure is required.

1 Overview

FTP is commonly run on two ports, 20 and 21. Port 20 is a data stream which transfers the data between the client and the server. Port 21 is the control stream and is the port where commands are passed to the ftp server. While data is being transferred via the data stream, the control stream sits idle. This can cause problems with large data transfers through firewalls which time out sessions after lengthy periods of idleness. While the file may well be successfully transferred, the control session can be disconnected by the firewall, causing an error to be generated.

The objectives of FTP are:

1. To promote sharing of files (computer programs and/or data).
2. To encourage indirect or implicit use of remote computers.
3. To shield a user from variations in file storage systems among different hosts.
4. To transfer dataA datum is a statement accepted at face value (a "given"). Data is the plural of datum''. A large class of practically important statements are measurements or observations of a variable. Such statements may comprise numbers, words, or images. Etymology T reliably and efficiently.

Disadvantages are:

1. PasswordFor information on the game Password see Password game. A password is a form of authentication which uses secret data to control access to a resource. The password is kept secret from those not allowed access, and those wishing to gain access are tested os and file contents are sent in clear textIn telecommunications, particularly data communications, cleartext is the form of a message or data which is transferred or stored without cryptographic protection. It is related to, but not entirely equivalent to, the term " plaintext". The phrases, in c, allowing eavesdroppingEavesdropping is the intercepting and reading of messages and conversations by unintended recipients. One who participates in eavesdropping, i. someone who secretly listens in on the conversations of others. The origin of the term is literal, from people which may be unwanted.
2. It is hard to filter active mode FTP traffic on the client side by using a firewallFirewalls protect against the spread of fire or of other danger. Firewalls in construction In the traditional meaning in construction, a firewall consists of a windowless, fireproof wall (or a wall of substantially heavier construction than other walls in, since the client must open a random port in order to make the connection. This problem is largely resolved by using passive mode FTP.
3. It is possible to tell a server to send to an arbitrary port of a third computer.

FTP, though usable directly by a user at a terminal, is designed mainly for use by FTP client programs.

Many sites that run FTP servers enable so-called " anonymous ftp". Under this arrangement, users do not need an account on the server. By default, the account name for the anonymous access is 'anonymous'. This account does not need a password. Although users are commonly asked to send their email addresses as their passwords for authentication, there is no verification.