1. Understanding FTP
File Transfer Protocol (FTP) is a protocol that serves for the exchange of files in a network that uses TCP rather than UDP connections. In the FTP server must have FTP and FTP Client.
FTP Server is a server that runs software that provides a file exchange service is always ready to provide FTP service on receiving requests from an FTP client.
FTP Client is the computer requesting a connection to the FTP server to exchange files. If connected to the FTP server, the client can download, upload, merename, to delete, etc. in accordance with permission granted by the FTP server.
1. FTP Security
FTP is not secure to transfer a file because the file is sent without being encrypted beforehand but when using SFTP (SSH FTP) FTP is based on using SSH or FTPS (FTP over SSL) so that the data will be sent encrypted beforehand.
1.In this mode FTP
FTP usually uses two ports to connect the port 20 and port 21 and walked Exclusively via TCP rather than UDP. FTP server listening on port 21 for incoming connection from the FTP client. Normally port 21 is the command port and port 20 is the data port. On the FTP server, there is a connection mode 2 active mode (active mode) and the passive mode (passive mode).
1. Active Mode
In active mode, the server is actively connected to the client. To make active setting mode, the client sends a command to the server port, specify the address and port number of clients who are hearing. When a connection is required, the server initiate a connection to the client at this address. In general, the server is responsible for closing these connections.
2. Passive Mode
In passive mode, the client start the connection with the server to solve the problem in the firewall filters data port connection to the client to the server. First, the client contact the server on port and issue the command PASV command. Server then provides the answer to port 2024, tells the client that the port is listening for data connections. Then, the client start the data connection from its data port to port data that have been determined by the server.
Example FTP server application:
- Proftpd
- Vsftpd
- Wuftpd
- IIS (inside there is an FTP Server)
Example FTP client application
- CuteFTP, Wget
- WsFTP
- GetRight
- AbsoluteFTP
1. FTP Commands
FTP Commands sent consist of simple text strings. For example, to get back files, the client sends "RETR filename" on the control connection to the FTP server. To transfer a file, the client sends "Stor filename". FTP server to know every command on every FTP response, which consists of three digits. The first digit indicates a good response, not good, or that are not perfect. If an error occurs, then the second digit is used to detect errors that occur. In the same way, the third digit is used to further specify the error. The first digit is the most important figures, and the possible values that appear are as follows:
* 1yz Positive Preliminary reply. Demand is known, but the other replies from the client still expected
* 2yz Positive Completion reply. Successful request made, so the client can send another request
* 3yz Positive Intermediate reply. Command has been received, but still need other information. Client is required to send other commands replies
* Transient Negative 4yz reply. Command failed, but there is still a chance to try again
* 5yz Permanent Negative Completion reply. Command failed, but did not have to be repeated again
Example FTP commands:
* To change the directory that is sent by the client:
CWD namadirektori
Server will respond with:
CDW command successful 250
In return, starting with a '2 ', where the sequence of completed orders.
* If you want to change one directory and it does not exist, then the command:
CWD namadirektoriyanghilang
Server will respond with:
550 namadirektoriyanghilang: The system can not find the file spesified
The reward is a '5 ', is to fail and still fail if it is repeated (except for missing directories are created on the server).
* Session Commands (Session Commands)
To start the FTP command session, then the USER command is sent to the server is:
USER chafid
Server will reply:
331 Password required for javaftp
Client must provide a reply by filling in the password:
PASS 123,456
Server will reply:
230 User logged in chafid
After login the user can use the commands associated with directories and files. To end, the client sends the following command:
QUIT
Server will reply:
221
Session was finally closed, so that any command that is sent is no longer acceptable.
1. Development goals FTP Server
* Sharing data
* Providing indirect or implicit remote computer
* Provide storage for the user
* Provide reliable data transfer and efficient
File Transfer Protocol (FTP) is a protocol that serves for the exchange of files in a network that uses TCP rather than UDP connections. In the FTP server must have FTP and FTP Client.
FTP Server is a server that runs software that provides a file exchange service is always ready to provide FTP service on receiving requests from an FTP client.
FTP Client is the computer requesting a connection to the FTP server to exchange files. If connected to the FTP server, the client can download, upload, merename, to delete, etc. in accordance with permission granted by the FTP server.
1. FTP Security
FTP is not secure to transfer a file because the file is sent without being encrypted beforehand but when using SFTP (SSH FTP) FTP is based on using SSH or FTPS (FTP over SSL) so that the data will be sent encrypted beforehand.
1.In this mode FTP
FTP usually uses two ports to connect the port 20 and port 21 and walked Exclusively via TCP rather than UDP. FTP server listening on port 21 for incoming connection from the FTP client. Normally port 21 is the command port and port 20 is the data port. On the FTP server, there is a connection mode 2 active mode (active mode) and the passive mode (passive mode).
1. Active Mode
In active mode, the server is actively connected to the client. To make active setting mode, the client sends a command to the server port, specify the address and port number of clients who are hearing. When a connection is required, the server initiate a connection to the client at this address. In general, the server is responsible for closing these connections.
2. Passive Mode
In passive mode, the client start the connection with the server to solve the problem in the firewall filters data port connection to the client to the server. First, the client contact the server on port and issue the command PASV command. Server then provides the answer to port 2024, tells the client that the port is listening for data connections. Then, the client start the data connection from its data port to port data that have been determined by the server.
Example FTP server application:
- Proftpd
- Vsftpd
- Wuftpd
- IIS (inside there is an FTP Server)
Example FTP client application
- CuteFTP, Wget
- WsFTP
- GetRight
- AbsoluteFTP
1. FTP Commands
FTP Commands sent consist of simple text strings. For example, to get back files, the client sends "RETR filename" on the control connection to the FTP server. To transfer a file, the client sends "Stor filename". FTP server to know every command on every FTP response, which consists of three digits. The first digit indicates a good response, not good, or that are not perfect. If an error occurs, then the second digit is used to detect errors that occur. In the same way, the third digit is used to further specify the error. The first digit is the most important figures, and the possible values that appear are as follows:
* 1yz Positive Preliminary reply. Demand is known, but the other replies from the client still expected
* 2yz Positive Completion reply. Successful request made, so the client can send another request
* 3yz Positive Intermediate reply. Command has been received, but still need other information. Client is required to send other commands replies
* Transient Negative 4yz reply. Command failed, but there is still a chance to try again
* 5yz Permanent Negative Completion reply. Command failed, but did not have to be repeated again
Example FTP commands:
* To change the directory that is sent by the client:
CWD namadirektori
Server will respond with:
CDW command successful 250
In return, starting with a '2 ', where the sequence of completed orders.
* If you want to change one directory and it does not exist, then the command:
CWD namadirektoriyanghilang
Server will respond with:
550 namadirektoriyanghilang: The system can not find the file spesified
The reward is a '5 ', is to fail and still fail if it is repeated (except for missing directories are created on the server).
* Session Commands (Session Commands)
To start the FTP command session, then the USER command is sent to the server is:
USER chafid
Server will reply:
331 Password required for javaftp
Client must provide a reply by filling in the password:
PASS 123,456
Server will reply:
230 User logged in chafid
After login the user can use the commands associated with directories and files. To end, the client sends the following command:
QUIT
Server will reply:
221
Session was finally closed, so that any command that is sent is no longer acceptable.
1. Development goals FTP Server
* Sharing data
* Providing indirect or implicit remote computer
* Provide storage for the user
* Provide reliable data transfer and efficient
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