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SAP Sybase SQL Anywhere 16.0 » SQL Remote » Managing SQL Remote systems » SQL Remote message systems » The FTP message system


Troubleshooting FTP problems

Most problems with the FTP message link are caused by network system issues. This section provides a list of tests you can use to troubleshoot problems.

  • Set the DEBUG message control parameter   Review the debug output to determine whether you are connecting to the FTP server. If you are connecting, the debug output should indicate which FTP commands are failing.

  • Ping the FTP server   If the FTP link is not able to connect to the FTP server, test your system network configuration. For example, run the following command:
    ping FTP-server-name

    The IP address of the FTP server and the ping (round trip) time to the FTP server should be returned. If you cannot ping the FTP server, then you have a network configuration problem, and you should contact you network administrator.

  • Check that passive mode works   If the FTP link is connecting to the FTP server, but is unable to open a data connection, make sure that an FTP client can use passive mode to transfer data with the server.

    Passive mode is the preferred transfer mode and the default for the FTP message link. In passive mode, all data transfer connections are initiated by the client, in this case, the message link. In active mode, the FTP server initiates all data connections. If your FTP server is behind an incorrectly configured firewall, you may not be able to use the default passive transfer mode because the firewall blocks socket connections to the FTP server on ports other than the FTP control port.

    Using an FTP user program that allows you to set the transfer mode between active and passive, set the transfer mode to passive and try to upload or download a file. If the client you are using cannot transfer the file without using active mode then you should reconfigure the firewall and FTP server to allow passive mode transfers or set the active_mode message control parameter to YES. Active mode transfers may not work in all network configurations. For example, if your client is behind an IP masquerading gateway incoming connections may fail depending on your gateway software.

  • Check permissions and directory structures   If the FTP server is connecting and having problems getting directory listings or manipulating files, make sure your permissions are set up correctly and the required directories exist.

    Log in to the FTP server using an FTP program. Change directories to the location stored in the root_directory parameter. If the directories you need do not appear, the root_directory control parameter may be set incorrectly or the directories may not exist.

    Test permissions by fetching a file in your message directory and uploading a file to the consolidated database directory. If errors are returned, your FTP server permissions are set up incorrectly.