File Transfer Protocol (FTP) is a TCP protocol for uploading and downloading files between computers. FTP works on a client/server model. The server component is called an FTP daemon. It continuously listens for FTP requests from remote clients. When a request is received, it manages the the login and sets up the connection. For the duration of the session it executes any of commands sent by the FTP client.
L'accès à un serveur FTP peut être réalisé de deux façons:
Anonyme
Authentifié
In the Anonymous mode, remote clients can access the FTP server by using the default user account called 'anonymous" or "ftp" and sending an email address as the password. In the Authenticated mode a user must have an account and a password. User access to the FTP server directories and files is dependent on the permissions defined for the account used at login. As a general rule, the FTP daemon will hide the root directory of the FTP server and change it to the FTP Home directory. This hides the rest of the file system from remote sessions.
vsftpd is an FTP daemon available in Ubuntu. It is easy to install, set up, and maintain. To install vsftpd you can run the following command:
sudo apt-get install vsftpd
You can edit the vsftpd configuration file,
/etc/vsftpd.conf
, to
change the default settings.
By default only anonymous FTP is
allowed. If you wish to disable this option, you
should change the following line:
anonymous_enable=YES
to
anonymous_enable=NO
By default, local system users are not allowed to login to FTP server. To change this setting, you should uncomment the following line:
#local_enable=YES
By default, users are allowed to download files from FTP server. They are not allowed to upload files to FTP server. To change this setting, you should uncomment the following line:
#write_enable=YES
Similarly, by default, the anonymous users are not allowed to upload files to FTP server. To change this setting, you should uncomment the following line:
#anon_upload_enable=YES
The configuration file consists of many configuration parameters. The information about each parameter is available in the configuration file. Alternatively, you can refer to the man page, man 5 vsftpd.conf for details of each parameter.
Une fois vsftpd configuré, vous pouvez démarrer le démon. La commande suivante permet de démarrer le démon vsftpd :
sudo /etc/init.d/vsftpd start
Veuillez noter que les réglages par défaut du fichier de configuration sont tels qu'ils sont pour des raisons de sécurité. Chacun des changements cités ci-dessus diminue la sécurité du système, par conséquent ne les appliquez qu'en cas de nécessité.