FTP display Illegal PORT command, Unknown command solution

This afternoon with Banana Pi in the dormitory open FTP server, open when there is no problem, the results of the computer on the ArchLinux connection, always hint to illegal PORT command, Unknown command.

Online search, are talking about the PASV and port mode switch, I tried to do a bit, or not.

Later, with the Mac system even a bit (arch is a virtual machine), found unexpectedly connected, and then in the arch with IP addr instructions to check the host ip,10.xxx, feel very strange, checked the original local area network. In other words, I use the virtual machine software (VIRTUALBOX) By default should be the host network to engage in a local LAN shared to the virtual machine. Is that the reason.

In the VirtualBox try to make a mess, the NAT model changed to bridge Adapter. And then back to arch, and then use IP addr Check, but also true, the IP has become and host, Banana Pi the same IP. And then again FTP opened a bit, successful.

(default setting)

(set after modification)

To sum up, the default NAT mode should be to create a new LAN, only host and virtual machine sharing, other devices such as Banana Pi does not belong to this LAN, so the virtual machine can not connect to it. Instead of bridging mode, the equivalent of VirtualBox a router function, assigned to the virtual machine a new IP, this time can be connected.