Intermittent "425 Unable to build data connection" error

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chafir
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Posts: 1
Joined: 2011-10-17 21:33

Intermittent "425 Unable to build data connection" error

#1 Post by chafir » 2011-10-17 21:41

Hi,

I am accessing an FTP server I have no configuration access to. Initially the connection is fine, and then the server appears to start refusing to grant me directory listings. Excerpts from the log below.

This link describes the same behavior and the "session reuse" description fits the symptoms I am seeing:
http://www.ateamsystems.com/blog/FireFT ... egotiation

Is there an option in FZ client to reuse SSL sessions?

Code: Select all

Status:	Resolving address of www.XXXXXX.com
Status:	Connecting to XXX.XXX.XXX.XXX:21...
Status:	Connection established, waiting for welcome message...
Response:	220 XXX.XXX.XXX.XXX FTP server ready
Command:	AUTH TLS
Response:	234 AUTH TLS successful
Status:	Initializing TLS...
Status:	Verifying certificate...
Command:	USER XXXXXX
Status:	TLS/SSL connection established.

(snip)

Status:	Retrieving directory listing...
Command:	CWD /home/XXXXXX/www/XXXXXX.com
Response:	250 CWD command successful
Command:	TYPE I
Response:	200 Type set to I
Command:	PASV
Response:	227 Entering Passive Mode (XXX,XXX,XXX,XXX,221,94).
Command:	MLSD
Response:	150 Opening ASCII mode data connection for MLSD
Response:	226 Transfer complete
Status:	Directory listing successful

(snip)

Status:	Retrieving directory listing...
Command:	CDUP
Response:	250 CDUP command successful
Command:	PWD
Response:	257 "/home/XXXXXX/www/XXXXXX.com" is the current directory
Command:	PASV
Response:	227 Entering Passive Mode (XXX,XXX,XXX,XXX,200,231).
Command:	MLSD
Response:	150 Opening ASCII mode data connection for MLSD
Response:	425 Unable to build data connection: Operation not permitted
Error:	Failed to retrieve directory listing

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Re: Intermittent "425 Unable to build data connection" error

#2 Post by botg » 2011-10-18 06:23

FileZilla already resumes TLS sessions on the data connection, but that does not appear to be the problem here.

According to the log, the server is denying the listing temporarily:
Response: 425 Unable to build data connection: Operation not permitted
Please contact the server administrator to remove whatever restriction is blocking you.

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