IBM Support

FTP 425 Error - Unable to Open Data Connection

Troubleshooting


Problem

A user is able to successfully FTP to the IBM® System i® products from a PC; however, the user is unable to open a data connection. The user is unable to use the commands dir, put, get, and so on.

Resolving The Problem

Any data connection type command (dir, put, get, and so on) fails with an FTP 425 message. The Microsoft® Windows®  operating system on the PC is implementing a PC side firewall that restricts port 20 for the data connection. Ending and removing the PC side firewall resolves the issue.

Additional symptoms:
Microsoft Windows uses FTP PORT mode.  In PORT mode, the FTP client determines the port for the data connection.
This PORT mode process causes the FTP server to initiate an FTP data connection from port 20 to the TCP port determined by the FTP client.

The 425 error could occur, if the network firewall does not allow SYN packets from the FTP server.

Review network firewall settings.

[{"Product":{"code":"SWG60","label":"IBM i"},"Business Unit":{"code":"BU070","label":"IBM Infrastructure"},"Component":"Communications-TCP","Platform":[{"code":"PF012","label":"IBM i"}],"Version":"Version Independent","Edition":"","Line of Business":{"code":"LOB68","label":"Power HW"}}]

Historical Number

390472854

Document Information

More support for:
IBM i

Software version:
Version Independent

Operating system(s):
IBM i

Document number:
638085

Modified date:
16 May 2024

UID

nas8N1015383

Manage My Notification Subscriptions