Writing firmware or modifying it for serious routers to protect against attacks?

Question

Computer networks

I want to write a firmware for a router (at first for my home one), and then for a more or less healthy one (like in a data center).
They seem to be written in C. The purpose of writing the firmware is to filter DDoS attacks
. Do you need to write the entire firmware for this, or can you edit the existing one?
What is the best language to write in? What do you need to learn to do this? (it is clear that it is necessary to fully study the operation of the Internet and other networks, protocols, etc.)

Answer 1

Terrible misunderstanding. Firmware is not written for "serious routers", they are configured by means provided by the manufacturer.
PS: I have more and more suspicions that you do not have any DDOS attacks, or these are some small attacks. Can you provide more technical information about attacks on you?

Answer 2

No firmware, even super-booper-Mega-awesome, stylish, youthful and written in assembler, will help against ddos ​​attacks. Only powerful hardware and only anycast bgp