NSX manager backups fails on FTP

Products

• VMware NSX

Issue/Introduction

• Creating an NSX Backup fails, you see an error similar to:
  File upload action aborted due to insufficient storage or invalid file name.( connect timed out)
• Manually copying a file from the NSX Manager to the FTP Sever using FTP with passive mode disabled, the server accepts the connection.
• Manually copying a file from the NSX Manager to the FTP Server using FTP with passive mode enabled, the server refuse the connection.

Environment

VMware NSX for vSphere 6.4.x
VMware NSX for vSphere 6.3.x

Resolution

To resolve this issue:

• Enable passive mode on the FTP server for the Backups.
• Set firewall to allow incoming connections on all ports greater than 1024 or configure FTP server to use a specific range of ports for passive mode connections and open those ports in the firewall.
• In the case of NAT router, forward these ports to the local machine FTP Server is installed on. Valid ports can be from 1 to 65535, however, ports less than 1024 are reserved for other protocols.
  
  Note: Due to the nature of TCP, a port cannot be reused immediately after each connection. Hence the range of ports should not be too small or transfers of multiple small files can fail. A range of 50 ports should be sufficient in most cases.