I had originally asked this question on https://networkengineering.stackexchange.com/ but was redirected here.
This is an informational question and I am not facing any DDoS attack of any sort. I was reading about DDoS attacks lately and there are quite a few online resources that give general info about DDoS defence techniques. I have a kind of a reverse question.
Suppose I receive a report that my server is contributing to DDoS attack on some xyz website. How do I verify this locally, at my end? And how to troubleshoot this? Is there a way to check how my server is contributing to this attack? like is it sending SYN flood or DNS amplification etc or is it a part of a wider botnet?