Jun Li is interested in cyber security and privacy, computer networking, distributed systems, blockchain, and Internet of things. He studies not only the functioning and performance of fundamental networking functions (e.g., routing and naming), various networking paradigms (e.g., software-defined networking, Internet of Things, data center networking, peer-to-peer networking), and popular applications and systems (e.g., online social networking), but also their problems in, or usage for, security and privacy. He studies both direct countermeasures against network security attacks (including Internet worms, phishing, botnets, and Sybil attacks) and fundamental security issues and solutions at the network architecture and protocol level (such as DDoS defense, Internet routing security, and DNS security).