227 Entering Passive Mode (xxx,xxx,,xxx,xxx,x)

Display 227 Entering Passive Mode (xxx,xxx,,xxx,xxx,x) when logged in to FTP

Because FTP has two modes of operation, port mode and PASV mode, Chinese meaning is active and passive, details are as follows:

Active FTP:
Command connection: client >1024 port → Server 21 port
Data connection: Client >1024 port ← Server 20 Port

Passive FTP:
Command connection: client >1024 port → Server 21 port
Data connection: Client >1024 port ← Server >1024 Port

The port (Active) connection process is: The client sends a connection request to the server's FTP port (by default, 21), the server accepts the connection, and establishes a command link. When the data needs to be transferred, the client tells the server with the Port command on the command link: "I opened the ***x port and you came over to connect me." The server then sends a connection request from Port 20 to the client's ***x port, creating a data link to transmit the data.

The PASV (passive) connection process is: The client sends a connection request to the server's FTP port (by default, 21), the server accepts the connection, and establishes a command link. When the data needs to be transferred, the server tells the client on the command link with the PASV command: "I opened the ***x port and you came over to connect me." The client then sends a connection request to the server's ***x port and establishes a data link to transmit the data.

The solution to this problem is also very simple, the PASV method of shutting down the client, forcing it to access the server by port, log on to the FTP server with the passive command to shut down the client PASV way, as follows:

ftp> Passive
Passive mode off.

ftp> Passive (Run command again to open)

Passive mode on.

The reason is that I set up a firewall today, only allowed 21 ports, and then changed to allow the server program is good

227 Entering Passive Mode (xxx,xxx,,xxx,xxx,x)