change specific linux iptables rule set to ipfw rule set

[Son, Yeongsik]

One of linux server contains rule set like these:

iptables -A INPUT -p tcp --syn --dport 80 - m connlimit --conlimit-above 20
-j DROP
iptables -A INPUT -m recent --name KIN -rcheck --seconds 300 -j DROP
iptables -A INPUT -p tcp --syn --dport 80 -m connlimit --connlimit-above 5
-m recent --name KIN -set -j DROP

simply means,
drop ip try to connect tcp port 80 over 20 connections.
when it happens, drop ip for 5 minutes.

iptables -A INPUT -p udp --dport 53 -m length --length 512:65535 -j DROP

briefly,
drop ip try to connect udp port 53 which packet length is 512 ~ 65535.

I want using those rules on freebsd servers, but I don't know those kind of
sophisticated functions of ipfw.

Is that possible freebsd?

Let me share your knowledge.