DOCUMENT:Q140424 19-FEB-2002 [winnt] TITLE :ErrMsg: "Invalid port command" AS400 Client FTP to NT 3.51 SP2 PRODUCT :Microsoft Windows NT PROD/VER::3.51 OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Workstation version 3.51 - Microsoft Windows NT Server version 3.51 ------------------------------------------------------------------------------- SYMPTOMS ======== IBM AS400 FTP client fails with the error "Invalid port command" when you try to ftp to Windows NT version 3.51 Service Pack 2 server. CAUSE ===== Windows NT 3.51 Server Service Pack 2 has added a new feature that rejects a client request for a TCP port number that is less than 1024. When this feature is implemented, an FTP session from an AS/400 client to the Windows NT 3.51 server may fail due to this added security feature." Ports numbers up to 1024 are reserved and used by well known applications. Port numbers above 1024 can be used arbitrarily by the user. When an ftp session is initiated from AS400 client, it might request for a TCP port number less than 1024 when a command is issued. This request is rejected by the Windows NT server and the client gets the above error. If more commands are issued from the client, it increments the TCP port number requested for every command issued and eventually when it reaches 1024, the request is accepted by the server. STATUS ====== This is by design. Additional query words: prodnt 3.51 ====================================================================== Keywords : Technology : kbWinNTsearch kbWinNTWsearch kbWinNT351search kbWinNTW351search kbWinNTW351 kbWinNTSsearch kbWinNTS351 kbWinNTS351search Version : :3.51 ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2002.