FTP not working, commands are async and random responses are returned

[bestrocker221]

Hi, when connecting via FTP towards the default conpot configuration, commands and response are randomly returned.

To Reproduce

1. conpot default template
2. ftp 2121
3. ls multiple times

Expected behavior

ftp> ls
150 Here comes the directory listing.
-rwxrwxrwx   1 nobody   ftp            49 Aug 01  2018 ftp_data.txt

Received:

ftp> ls
226 Transfer complete.
200 PORT Command Successful. Consider using PASV.
ftp> ls
150 Here comes the directory listing.
ftp> ls
226 Directory send OK.
200 PORT Command Successful. Consider using PASV.
ftp> ls
150 Here comes the directory listing.
ftp> ls
226 Directory send OK.
226 Transfer complete.
ftp> ls
150 Here comes the directory listing.
ftp> ls
226 Directory send OK.
501 Invalid PORT format.
ftp> ls
200 PORT Command Successful. Consider using PASV.
150 Here comes the directory listing.
-rwxrwxrwx   1 nobody   ftp            49 Aug 01  2018 ftp_data.txt
226 Directory send OK.
ftp> ls
226 Transfer complete.
200 PORT Command Successful. Consider using PASV.
ftp> ls
150 Here comes the directory listing.
ftp> ls
226 Directory send OK.
501 Invalid PORT format.

Desktop (please complete the following information):

• OS: Debian 11
• kernel 5.16