In recent years, machine learning-based anomaly detection (AD) has become an important measure against security threats from Internet of Things (IoT) networks. Machine learning (ML) models for network traffic AD require datasets to be trained, evaluated and compared. Due to the necessity of realistic and up-to-date representation of IoT security threats, new datasets need to be constantly generated to train relevant AD models. Since most traffic generation setups are developed considering only the author’s use, replication of traffic generation becomes an additional challenge to the creation and maintenance of useful datasets. In this work, we propose GothX, a flexible traffic generator to create both legitimate and malicious traffic for IoT datasets. As a fork of Gotham Testbed, GothX is developed with five requirements: 1)easy configuration of network topology, 2) customization of traffic parameters, 3) automatic execution of legitimate and attack scenarios, 4) IoT network heterogeneity (the current iteration supports MQTT, Kafka and SINETStream services), and 5) automatic labeling of generated datasets. GothX is validated by two use cases: a) re-generation and enrichment of traffic from the IoT dataset MQTTset,and b) automatic execution of a new realistic scenario including the exploitation of a CVE specific to the Kafka-MQTT network topology and leading to a DDoS attack. We also contribute with two datasets containing mixed traffic, one made from the enriched MQTTset traffic and another from the attack scenario. We evaluated the scalability of GothX (450 IoT sensors in a single machine), the replication of the use cases and the validity of the generated datasets, confirming the ability of GothX to improve the current state-of-the-art of network traffic generation.