All Xiongmai devices come with a feature called “XMeye P2P Cloud”. It is a proprietary, UDP-based protocol that allows users to access their IP cameras or NVRs/DVRs via the internet. The feature is enabled by default, no setup by the user is required.

https://sec-consult.com/en/blog/advisories/vulnerabilities-xiongmai-ip-cameras-nvrs-dvrs-cve-2018-17915-cve-2018-17917-cve-2018-17919/