ipf rules

pass in quick on sip0 proto tcp from any to 83.xxx.104.34 port = 21 keep state # FTP Cmd
pass in quick on sip0 proto tcp from any to 83.xxx.104.34 port 64000 >< 65000 flags S keep state # FTP Passive
pass in quick on sip1 proto tcp from 83.xxx.104.34 port = 20 to any keep state # FTP Data (Active)

SIP0 is the Public Interface, SIP1 is the DMZ One. 83.xxx.104.34 is the public FTP's address

Configuration sample (proftpd)

PassivePorts                    64000 65000
IdentLookups                    off

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