ext_if="wi0"
int_if="xl0"
lan="192.168.0.0/24"

nat on $ext_if proto ip from $lan to !$lan -> $(ext_if)

block in all
block out all

pass in on $int_if proto ip from any to any keep state
pass out on $int_if proto ip from any to any keep state
pass out on $ext_if proto ip from any to any keep state