If passive FTP is not working on a Linux system, there are a few things you can try to troubleshoot the problem:
Make sure that the FTP server is configured to support passive FTP. In most FTP servers, passive FTP is enabled by default, but it can be disabled in the configuration file.
Check the firewall rules to make sure that the necessary ports are open. Passive FTP uses a range of dynamic ports for data transfer, so you will need to allow incoming and outgoing connections on a wide range of ports.
Check the NAT configuration to make sure that the necessary ports are being forwarded. If the FTP server is behind a NAT router or firewall, you will need to configure port forwarding to allow the dynamic ports used by passive FTP to be forwarded to the FTP server.
Check the logs on the FTP server and client to see if there are any error messages or other clues about what might be causing the problem.
If you are using a client-side firewall or antivirus software, make sure that it is not blocking the necessary ports.
Make sure that the FTP server is listening on the correct IP address and port. If the FTP server is listening on the wrong IP address or port, it may not be able to accept connections from the client.
If none of these solutions work, you may need to troubleshoot the problem further by checking the system logs, configuration files, and other relevant system resources. It's also possible that there is a bug in the FTP software or a problem with the network that is preventing passive FTP from working correctly.