Passive - H3C S3100 Series Command Manual

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# Establish a control connection with the FTP server whose IP address is 1.1.1.1 in FTP client view.

[ftp]open 1.1.1.1

Press CTRL+K to abort

220 FTP service ready.

User(none):abc

331 Password required for abc

230 User logged in.

passive

undo passive

FTP client view

Use the passive command to set the data transfer mode to the passive mode.

Use the undo passive command to set the data transfer mode to the active mode.

By default, the passive mode is adopted.

The differences between the passive mode and the active mode are:

When working in the active mode, an FTP client advertises a random port Port1 to an FTP server

through TCP port 21; upon receiving the advertisement, the FTP server initiates a connection with

Port1 on the client for data transmission.

When working in the passive mode, an FTP client sends a passive request to the FTP server

before data transmission, the FTP server advertises a local random port Port2 to the FTP client,

and the FTP client establishes a connection with Port2 using a local random port.

If an FTP client initiates a connection with an FTP server through a firewall, the firewall may block the

connection request because the FTP server initiates the connection with Port1 through an external

network, and thus data transmission will be affected. Therefore, you are recommended to set the data

transmission mode of the FTP client to passive when accessing the FTP server through a firewall.

# Set the data transfer mode to the passive mode.

[ftp] passive

% Passive is on

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