The tools used to enable file transfers over the internet are called FTP servers. After an established relationship, data is sent between the client and server over these ports.

The client makes the connection from Random Port 2 to port 3 chosen by the server. To notify the client what port on the server it has to connect to make the connection, it sends the PASV command. Connecting from a client’s random port (in this case, random port 1) to the server’s port 21 is how this mode works. Since the client is often located behind a firewall, this configuration is the most typical (e.g. The passive mode must be used when a client cannot initiate communication due to external factors such as a firewall. In this case, the server establishes a connection from port 20 to the client-specified port, Random Port 2. It informs the server of the client’s port number through the PORT command (random port 2). In active mode, the user connects their FTP client (using a random port, say 1) to the server (using port 21). Anonymous FTP servers are what their name implies.ĭata Connection - a special connection for sending and receiving data like files and folders. However, other servers provide access to their whole database without authentication. A user’s login credentials are required to create a connection to the FTP server. It’s a two-way communication system for issuing orders and getting results.

Typically, FTP clients like FileZilla and FileZilla Pro will initiate a connection to the server’s port number 21 to exert control over the link. Where does the magic happen in the File Transfer Protocol?Ĭonsidering that FTP is a client-server protocol, it requires two-way communication between the client and the server. Said it’s a method for securely transferring data between parties. The file transfer protocol is fundamentally a method of securely establishing a connection between two computers to facilitate data movement between two or more locations. FTP, or File Transfer Protocol, maybe a term you are familiar with but may not fully understand.

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