ext_if="rl0"
int_if="xl0"

tcp_services="{ 22, 113 }"
icmp_types="echoreq"

set block-policy return
set loginterface $ext_if

set skip on lo

scrub in

nat on $ext_if from !($ext_if) -> ($ext_if:0)
nat-anchor "ftp-proxy/*"
rdr-anchor "ftp-proxy/*"

rdr pass on $int_if proto tcp to port ftp -> 127.0.0.1 port 8021

block in

pass out keep state

anchor "ftp-proxy/*"
antispoof quick for { lo $int_if }

pass in on $ext_if inet proto tcp from any to ($ext_if) \
   port $tcp_services flags S/SA keep state

pass in inet proto icmp all icmp-type $icmp_types keep state

pass in quick on $int_if