ftp_pasv()

(PHP 4, PHP 5, PHP 7)

返回当前 FTP 被动模式是否打开

说明

ftp_pasv(resource $ftp_stream,bool $pasv): bool

在被动模式打开的情况下，数据的传送由客户机启动，而不是由服务器开始。

请注意ftp_pasv()只能在 FTP 登录成功后方可调用，否则会失败。

参数

$ftp_stream: FTP 连接资源。
$pasv: 如果参数$pasv为TRUE，打开被动模式传输(PASV MODE)，否则则关闭被动传输模式。

返回值

成功时返回TRUE，或者在失败时返回FALSE。

范例

ftp_pasv()实例

<?php
$file = 'somefile.txt';
$remote_file = 'readme.txt';
// set up basic connection
$conn_id = ftp_connect($ftp_server);
// login with username and password
$login_result = ftp_login($conn_id, $ftp_user_name, $ftp_user_pass);
// turn passive mode on
ftp_pasv($conn_id, true);
// upload a file
if (ftp_put($conn_id, $remote_file, $file, FTP_ASCII)) {
 echo "successfully uploaded $file\n";
} else {
 echo "There was a problem while uploading $file\n";
}
// close the connection
ftp_close($conn_id);
?>

It should be noted that ftp_pasv has to be called AFTER ftp_login (not after ftp_connect). May seem obvious to many but it took me three hours to find out...

If you are still having problems after choosing ftp_pasv() you should refresh the connection through ftp_close() / ftp_connect() after x files and/or y GB have been transfered.
It solved several (random) occurring problems like:
ftp_get(): Opening BINARY mode data connection
ftp_get(): Entering Passive Mode
Hint: fopen() created a file so don't forget to delete it if an error occurred ;)

For some FTP servers, it seems the sequence of passive and other commands matters more than for other FTP servers. Sorry, I don't know what vendor or version specifically.
<?php
ftp_pasv($handle, true);
echo "System type: ".ftp_systype($handle).PHP_EOL;
ftp_fput($handle, 'example.txt', $stream, FTP_BINARY);
?>
> PHP Warning: ftp_fput(): STOR out of sequence.
<?php
echo "System type: ".ftp_systype($handle).PHP_EOL;
ftp_pasv($handle, true);
ftp_fput($handle, 'example.txt', $stream, FTP_BINARY);
?>
> no issue

If you are running filezilla in passive mode, on windows, and try to connect using PHP, you might encounter an error that reads "425 Can't open data connection for transfer of ..."
This error is not indicative of a passive mode issue, but can be resolved by using 
<?php
ftp_pasv($conn, true);
?>

If you find that you are receiving "Illegal PORT command" errors you may want to try enabling passive mode.

I found one place that required passive mode to function properly, but the initial error manifested itself in an odd way:
PHP Warning: ftp_put(): TYPE is now ASCII in <file.php> on line <#>
or 
PHP Warning: ftp_put(): TYPE is now 8 BIT BINARY in <file.php> on line <#>
The other symptom is that it was taking a long time, perhaps the 90 seconds that the timeout was set to. No errors occurred upon connect, just when I tried ftp_put().
Once I turned on ftp_pasv() it worked, both in the place where active mode worked, and on the server where active mode wouldn't work.

Directly from bsd FTP manual pages:
The PASV command requests that the remote server open a port for the data connection and return the address of that port. The remote server listens on that port and the client connects to it.
         When using the more traditional PORT command, the client listens on a port and sends that address to the remote server, who connects back to it. Passive mode is useful when using ftp through a gateway router or host that controls the directionality of traffic. (Note that though ftp servers are required to support the PASV command by RFC 1123, some do not.)

PASV: For ftp users behind firewall, the server LISTEN for a connection. 
Non-PASV: The client LISTEN for a connection from server.