I have not seen any questions regarding to packet filter in Python and I am wondering, If it's possible to build it at all.
Is there any way building a custom firewall in Python? Null-routing specific IP's for example, or blocking them when request amount capacity is reached in 5 seconds. 
What modules would it need, would it be extra difficult? Is Python useful for things like firewall?
Also would it be possible to add powerful protection? So it can filter packets on all the layers.

I'm not asking for script or exact tutorial to build it, my sorted question:
How possible would it be to build firewall in Python? Could I make it powerful enough to filter packets on all layers? would it be easy to build simple firewall?
Yes, that would be possible, Python has a large networking support (I would starting with the socket module, see the docs for that).
I would not say that it will be easy or build in a single weekend, but you should give it a try and spend some time on it!
Packet filter in Python?