useradd -m tuxftp
passwd tuxftp
apt install proftpd
UseIPv6 off
...
DefaultRoot ~
systemctl start proftpd.service
PassivePorts 49152 49153
MasqueradeAddress 10.10.Y.100+X #внешний ip ВМ gwX
iptables -t nat -A PREROUTING -i enp0s3 -p tcp --dport 21 -j DNAT --to-destination 10.20.30.2:21
iptables -t nat -A PREROUTING -i enp0s3 -p tcp --dport 49152 -j DNAT --to-destination 10.20.30.2:49152
iptables -t nat -A PREROUTING -i enp0s3 -p tcp --dport 49153 -j DNAT --to-destination 10.20.30.2:49153