# create dummy
-I -s 1.1.1.1 -d 2.2.2.2 -p tcp --sport 10 --dport 20 --state LISTEN -u SEEN_REPLY -t 50 ; OK
# delete bad source
-D -s 2.2.2.2 -p tcp --sport 10 --dport 20 ; BAD
# delete by source
-D -s 1.1.1.1 ; OK