ftp-proxy, Pre-4.7

In the base system, load the daemon if you need it




NAT section anchors

nat-anchor "ftp-proxy/*"
rdr-anchor "ftp-proxy/*"

the redirection

rdr pass on $int_if proto tcp from any to any port ftp -> \
         port 8021

in your filtering section

anchor "ftp-proxy/*"
pass out proto tcp from $proxy to any port 21 keep state