What are some common challenges when configuring iptables for DDoS mitigation, and how can they be addressed?

Challenges include accurately identifying malicious traffic, avoiding false positives (blocking legitimate users), and keeping the rules up-to-date as the attack evolves. Addressing these requires careful monitoring, analysis of traffic patterns, and a flexible rule set that can be adjusted as needed. Using a DDoS mitigation service can also help filter traffic before it reaches your server.