El siguiente modelo representa el diagrama de un FTP service.
In the model, the protocol interpreter (PI) user initiates the control connection on port 21. Standard FTP commands are generated by the IP user and transmitted to the server process via the control connection. The standard responses are sent from the IP of the server to user IP control connection in response to orders.
These orders specify parameters for the FTP data connection (data port, transfer mode, representation type and structure) and the nature of the operation on the file system (store, retrieve, add, delete, etc.). The data transfer process (DTP) user or other process in place, you should wait until the server starts the connection to the specified data port (port 20 in active mode or standard) and transfer data according to the parameters specified.
We also see in the diagram that the communication between client and server is independent of file system used on each computer so that no matter what operating systems are different, because the entities that communicate with each other are the IP and the DTP, using the same standard protocol FTP.
also noticed that the data connection is bidirectional, ie can be used simultaneously to send and receive, and do not have to exist throughout the duration of the FTP connection .
FTP Server An FTP server is a special program that runs on a server computer usually connected to the Internet (although it can be connected to other types of networks, LAN, MAN , etc.). Its function is to allow the exchange of data between servers / computers.
usually FTP server programs not usually found in personal computers, so that a user typically will use FTP to connect remotely to one and thus exchange information with him.
The most common application servers FTP is often the hosting , in which customers use the service to upload your web pages and their corresponding files, or as a backup server (backup) of important files you may have a business. To do this, there are FTP communication protocols to transmit encrypted data, such as SFTP (Secure File Transfer Protocol). FTP Client
When a browser is not equipped with the FTP, or if you want to upload files to a remote computer, you need to use an FTP client program. An FTP client is a program that is installed on the user's computer, which uses the FTP protocol to connect to a server FTP and transfer files, either for download or upload.
To use an FTP client, you need to know the name of the file, the computer on which it resides (server, for downloading), the computer you want to transfer the file (if we want to upload to the server ), and the folder where you are.
Some basic FTP client in console mode are integrated into operating systems, including Windows, DOS, Linux and Unix. However, customers are available and added GUI options. Although many browsers are already integrated FTP is more reliable when connecting to anonymous FTP servers use a client program.
Anonymous access
anonymous FTP servers offer their services free to all users, allow access to their files without having a 'USERID' or a user account. It is the most comfortable out of the web service to allow everyone to have access to certain information and who do a system administrator has to create an account for each user . If a server has
service 'anonymous FTP' just by typing the word "anonymous" when prompted for your user have access to that system. You need no default password, but you will have to enter one just for that moment, usually tends to use the email address itself.
this is achieved only with access to FTP files, but with fewer privileges than a normal user. Normally you can only read and copy existing files, but not modify or create new ones.
User Access
If you want to have access privileges to any part of the FTP server file, modifying existing files, and our own ability to upload files, it is generally performing using a user account. On the server saves the information from different user accounts can access it, so that FTP log must enter a login and password that uniquely identifies us
Guest Access
Unrestricted access to the server that provides user accounts involves security issues, which has led to a FTP access third type called guest (guest), which can be viewed as a mixture of the two.
The idea of \u200b\u200bthis mechanism is as follows: This is to allow each user to connect to the machine using your login and password, but prevent access to parts of the file system does not need to do their jobs, so access a restricted environment, something very similar to what happens in the anonymous access, but with more privileges.
These orders specify parameters for the FTP data connection (data port, transfer mode, representation type and structure) and the nature of the operation on the file system (store, retrieve, add, delete, etc.). The data transfer process (DTP) user or other process in place, you should wait until the server starts the connection to the specified data port (port 20 in active mode or standard) and transfer data according to the parameters specified.
We also see in the diagram that the communication between client and server is independent of file system used on each computer so that no matter what operating systems are different, because the entities that communicate with each other are the IP and the DTP, using the same standard protocol FTP.
also noticed that the data connection is bidirectional, ie can be used simultaneously to send and receive, and do not have to exist throughout the duration of the FTP connection .
FTP Server An FTP server is a special program that runs on a server computer usually connected to the Internet (although it can be connected to other types of networks, LAN, MAN , etc.). Its function is to allow the exchange of data between servers / computers.
usually FTP server programs not usually found in personal computers, so that a user typically will use FTP to connect remotely to one and thus exchange information with him.
The most common application servers FTP is often the hosting , in which customers use the service to upload your web pages and their corresponding files, or as a backup server (backup) of important files you may have a business. To do this, there are FTP communication protocols to transmit encrypted data, such as SFTP (Secure File Transfer Protocol). FTP Client
When a browser is not equipped with the FTP, or if you want to upload files to a remote computer, you need to use an FTP client program. An FTP client is a program that is installed on the user's computer, which uses the FTP protocol to connect to a server FTP and transfer files, either for download or upload.
To use an FTP client, you need to know the name of the file, the computer on which it resides (server, for downloading), the computer you want to transfer the file (if we want to upload to the server ), and the folder where you are.
Some basic FTP client in console mode are integrated into operating systems, including Windows, DOS, Linux and Unix. However, customers are available and added GUI options. Although many browsers are already integrated FTP is more reliable when connecting to anonymous FTP servers use a client program.
Anonymous access
anonymous FTP servers offer their services free to all users, allow access to their files without having a 'USERID' or a user account. It is the most comfortable out of the web service to allow everyone to have access to certain information and who do a system administrator has to create an account for each user . If a server has
service 'anonymous FTP' just by typing the word "anonymous" when prompted for your user have access to that system. You need no default password, but you will have to enter one just for that moment, usually tends to use the email address itself.
this is achieved only with access to FTP files, but with fewer privileges than a normal user. Normally you can only read and copy existing files, but not modify or create new ones.
User Access
If you want to have access privileges to any part of the FTP server file, modifying existing files, and our own ability to upload files, it is generally performing using a user account. On the server saves the information from different user accounts can access it, so that FTP log must enter a login and password that uniquely identifies us
Guest Access
Unrestricted access to the server that provides user accounts involves security issues, which has led to a FTP access third type called guest (guest), which can be viewed as a mixture of the two.
The idea of \u200b\u200bthis mechanism is as follows: This is to allow each user to connect to the machine using your login and password, but prevent access to parts of the file system does not need to do their jobs, so access a restricted environment, something very similar to what happens in the anonymous access, but with more privileges.
client connection modes
FTP FTP supports two modes of client connection. These modes are called active (or Standard, or PORT, because the client sends PORT commands to the server type for the control channel to establish connection) and Passive (or PASV, because in this case sends PASV command). Both Active mode and Passive mode, the client establishes a connection to the server using port 21, which establishes the control channel.
Active Mode In active mode, the server always creates the data channel on your port 20, while client-side data channel is associated with a random port greater than 1024. To do this, the client sends a PORT command to the server for control channel indicating that port number, so that the server can open a data connection where files are transferred and tier two, on the specified port.
passive mode when the client sends a PASV command over the control channel, the FTP server opens an ephemeral port (either between 1024 and 5000) and informs the FTP client, in this so, whether the client who connect to that server and port is not necessary to accept random connections unsafe for data transfer.
before each new transfer, both in the active mode and the liability, the client must send back a control command (PORT or PASV, after the manner in which it is connected), and the server will receive the data connection a new random port (if in passive mode) or port 20 (if it is in active mode). 'Text in italics
negritaTexto before each new transfer, both in the active mode and the liability, the client must send back a control command (PORT or PASV, after the manner in which it is connected), and the server will receive the data connection a new random port (if in passive mode) or port 20 (if it is in active mode). 'Text in italics
Types FTP file transfer
is important to know how we transport a file over the network. If you do not use these options can destroy information on file. So, when you run the FTP application, we must remember to use one of these commands (or put the appropriate option in a program with graphical interface): ascii
° Type Suitable for transferring files containing only printable characters (ASCII files, not files resulting from a word processor), for example HTML pages, but not the images contained therein.
binary
° Type This type is used when dealing with compressed files, executables for PC, images, audio files ...
Examples of how to transfer some file types depending on its length:
° Type Suitable for transferring files containing only printable characters (ASCII files, not files resulting from a word processor), for example HTML pages, but not the images contained therein.
binary
° Type This type is used when dealing with compressed files, executables for PC, images, audio files ...
Examples of how to transfer some file types depending on its length:
