FTP may operate in an active or a passive mode, which determines how a data connection is established. 150 Opening BINARY mode data connection for ftp.xml. Il le rend assez inutile de nos jours en raison de pare-feu omniprésents et NATs. During a typical active mode session, the command port uses port 21 and the data port uses port 20. In active mode, the client connects to the server to establish the command channel, but the server connects back to the client to establish the data channel. 226 Transfer complete.

In both cases, a client creates a TCP control connection to an FTP server command port 21.


Passive FTP (sometimes referred to as PASV FTP because it involves the FTP PASV command) is a more secure form of data transfer in which the flow of data is set up and initiated by the File Transfer Program (FTP) client rather than by the FTP server program. In active mode FTP the client connects from a random unprivileged port (poer number > 1023) to the FTP server's command port, port 21. Active/Passive is controlled by the client, not the server. The main difference is that EPSV and Extended Passive Mode are primarily designed to accommodate both IPV4 and IPV6 addresses, while the older PASV command and Passive Mode could only support IPV4. Then, the client starts listening to port N+1 and sends the FTP command PORT N+1 to the FTP server. And, if you do a trace or inspect a debug log of an FTP/S session, you'll notice that the FTP/S server responds with: Mode passif : En mode passif, le serveur FTP détermine lui-même le port de connexion à utiliser pour permettre le transfert des données (data connexion) et le communique au client.

Common responses. This command tells the server to enter a passive FTP session rather than Active.
The server will then connect back to the client's specified data port from its local data port, which is port 20. total 0 226 Transfer complete. ftp> put ftp.xml local: ftp.xml remote: ftp.xml 200 PORT command successful. Below is a list of FTP commands that may be sent to an FTP server, including all commands that are standardized in RFC 959 by the IETF.All commands below are RFC 959 based unless stated otherwise. FTP uses a data port and a command port to transfer information between a client and a server.

In such a case, passive mode can be useful. À cette commande, le serveur va répondre une liste de ports vers lesquels le client pourra ouvrir une connexion TCP pour un data channel, exemple : Command: PASV Response: 227 Entering Passive Mode (213,186,33,201,249,35) PASV mode has the server tell the client where to connect the data port on the server. 227; 421