Recreate the problem and deactivate the traces. If you do not have SYSLOGD configured and running correctly, reference MustGather: Collect Troubleshooting Data, Read First: Syslogd for z/OS Communications Server.Ĥ. The output of this trace will be sent to the SYSLOGD application. MODIFY ftp_server_jobname, DEBUG=(FLO,BAS)ģ. This can be done by issuing the following MVS MODIFY command prior to starting the failing data transfer (where ftp_server_jobname is the name under which the FTP server is running, such as FTPD1 or FTPSERV): Obtain an FTP server trace with options BAS and FLO. If this is a high-volume system, be sure to reference section 6 on how to filter tracing based on IP addresses and ports.Ģ. Detailed instructions for doing this can be found in Informational APAR II12014.

Steps to follow to resolve FTP errors during data connection establishment for the server:ġ. If the server is z/OS, see the section on Determining if you need a portrange for the FTP server, which will provide instructions on how to configure FTP to use only ports authorized on the firewall. Note that the FTP server will, by default, use port 20 for active connections, and will use an ephemeral port for passive connections. It is possible that the port the FTP server is using is not included in a range that has been defined on your firewall. As a result, if the mode in which the data connection is established is related to the error, then further investigation must be done on the FTP client. Of note, data connections can be passive (the client opens a connection to the server) or active (the server opens a connection to the client), but the client controls which method is used. When trying to establish the data connection, errors may arise, most commonly manifested as an FTP reply such as 425 Can't open data connection or 425 Unable to open data connection. However, whenever data is transferred, FTP opens a new connection called the data connection.Ĭommands which result in the opening of a data connection include LS, DIR, GET, MGET, PUT, and MPUT. During a typical FTP connection, messages flow back and forth between the FTP client and the server across the control connection (this is the connection usually established on port 21).

Ftp error unknown host or port