In this paper, we introduce PANTHER, a modular framework for testing network protocols and formally verifying their specification. The framework incorporates a plugin architecture to enhance flexibility and extensibility for diverse testing scenarios, facilitate reproducible and scalable experiments leveraging Ivy and Shadow, and improve testing efficiency by enabling automated workflows through YAML-based configuration management. Its modular design validates complex protocol properties, adapts to dynamic behaviors, and facilitates seamless plugin integration for scalability. Moreover, the framework enables a stateful fuzzer plugin to enhance implementation robustness checks.