522: network protocol netprt_specified not consistent with this session. Use netprt_allowed.

Explanation

The FTP client sent an EPRT command to the z/OS® FTP server to establish a data connection. The network protocol specified on the EPRT command is not allowed for the current session because it is not the same protocol the client used to log in to FTP.

netprt_specified is the network protocol address family number specified on the EPRT command.

netprt_allowed is the network protocol address family number allowed for the current session.

Address family (AF) numbers correspond to protocols supported by the FTP server. The address family numbers are defined in RFC 1700. See Related protocol specifications for information about accessing RFCs. The FTP server might return one of these values:
AF number
Protocol
1
Internet Protocol Version 4
2
Internet Protocol Version 6

The z/OS FTP server supports both IPv4 and IPv6, but the EPRT command is not allowed to specify a protocol different from that used for the current session. An FTP client may send such a command when the user is attempting proxy transfer between two servers known to the client by IP addresses of different protocol families.

System action

The FTP server rejects the EPRT command. Processing continues.

User response

If you received this reply while attempting a proxy transfer of data between two servers, and the file transfer failed subsequent to this reply, try one of the strategies listed below. If you received this reply under any other circumstance, report the error to the system programmer.
  • Log in to the FTP servers as before, but reverse the order in which you log in to those servers. Try the proxy transfer again. The strategy is to reverse the roles of the FTP servers from the client's perspective so that the FTP client sends PORT or EPRT to the other FTP server.
  • Log in to each server again by specifying server IP addresses of the same protocol family, and try the proxy transfer again. If you know the servers only by DNS names, ask the system programmer what the server IP addresses are. If both servers are z/OS FTP servers, this is the only way to successfully proxy transfer files.
  • If neither of the above strategies succeeds, you cannot proxy transfer files directly between the servers. Transfer the file first to the client, then from the client to the other server.

System programmer response

If the user is attempting proxy transfer, verify that the user correctly attempted the strategies described under User or Operator Response. Otherwise, report the error to the provider of the FTP client software.