I'm trying to redirect port 80 to 3000 and I'm having trouble combining it to my filter rules. Both *nat and *filter rules work correctly when used separately, but not when applied together *nat ...

At my current job, we use shorewall extensively. I can't say that it's much better, especially if you ever want to look at the output of iptables -l or if you just have a few policies. That being said ...