ftp-proxy: bind failed: Address already in use

[Mistery]

Hello all, i am trying to setup ftp-proxy to allow external FTP clients to connect to internal FTP server, i followed the wiki and the setup should be ok however ftp-proxy is not starting (yellow background shown).
Starting from CLI it shows the following

# /usr/local/etc/rc.d/os-ftp-proxy start
osftpproxy is not running.
Starting osftpproxy.
ftp-proxy: bind failed: Address already in use
/usr/local/etc/rc.d/os-ftp-proxy: WARNING: failed to start osftpproxy

however there is nothing already bound to 127.0.0.1:8021

# netstat -ln | grep 127.0.0.1
tcp4       0      0 127.0.0.1.27017                               127.0.0.1.10607                               ESTABLISHED
tcp4       0      0 127.0.0.1.10607                               127.0.0.1.27017                               ESTABLISHED
tcp4       0      0 127.0.0.1.27017                               127.0.0.1.34104                               ESTABLISHED
tcp4       0      0 127.0.0.1.34104                               127.0.0.1.27017                               ESTABLISHED
udp4       0      0 127.0.0.1.53                                  *.*                                           
udp4       0      0 127.0.0.1.123                                 *.*                                           
udp4       0      0 127.0.0.1.46849                               127.0.0.1.9996                               
udp4       0      0 127.0.0.1.60625                               127.0.0.1.9996                               
udp4       0      0 127.0.0.1.27715                               127.0.0.1.9996                               
udp4       0      0 127.0.0.1.2056                                *.*                                           
udp4       0      0 127.0.0.1.2055                                *.*                                           
udp4       0      0 127.0.0.1.29634                               127.0.0.1.2055       

Any ideas about what could be causing this issue ?

ftp-proxy setup is the same shown in reverse FTP proxy tutorial on this forum, I have just set the source address to match the WAN CARP address where the remote FTP clients will connect to and the reverse address to match the internal FTP server IP address.

[Mistery]

Also it seems like ftp-proxy is running

# ps aux | grep ftp-proxy
proxy   54011   0.0  0.1 1057704   2728  -  Ss   09:35    0:00.00 /usr/sbin/ftp-proxy -b 127.0.0.1 -p 8021 -a <WAN_CARP_IP> -R <Internal_FTP_Server_IP> -v -D 7

however no PID file

# ls /var/run/osftpproxy*
ls: No match.

I am currently running 20.1.7 with latest updates applied, anybody else is experiencing such issue ?

Maybe I hit a bug in current release ?

[Mistery]

I did some more tests and this definitely looks to me like a BUG, even disabling the ftp proxy in web GUI the process remains in memory, therefore something is not working.
I have just installed the ftp-proxy plugin and configured as per the tutorial in this forum on 20.1.7 release therefore i cannot say whether it was working before or not.