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FTP Client connection attempt fails with "421 service not available."



FTP Client connection attempt fails with "421 service not available."


When attempting to connect to a remote FTP server, the iseries FTP Client connection fails with "421 service not available."


FTP Client

Resolving The Problem

Typically this type of error would make us think that the remote FTP server is not responding to the initial SYN packet sent from the iseries FTP client. What was found in the communications trace is that at the FTP client side we were completing the 3 part handshake (SYN, ACK SYN, ACK), but then instead of getting a sign on screen the FTP server was sending us the "421 Service not available." In this case it would have to be investigated why the FTP server is not functioning properly to provide the client with the sign on.

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Document Information

Modified date:
18 December 2019