nat-anchor "ftp-proxy/*"
rdr-anchor "ftp-proxy/*" 
rdr pass on $int proto tcp from any to any port ftp -> 127.0.0.1 port 8021
rdr pass on $vp proto tcp from any to any port ftp -> 127.0.0.1 port 8021
pass out on $int keep state
pass out on $vp keep state