Internet UDP port 5353 is primarily used by Multicast DNS (mDNS) protocol. This protocol is implemented in various software and systems, including Apple's Bonjour service and Linux's Avahi service. These services use mDNS to discover other devices on the same local network, enabling features like file sharing and printer sharing. Additionally, the Home Assistant open-source home automation platform uses this port for the discovery of network devices and services.
UDP port 5353 is associated with the Multicast DNS (mDNS) service, which is used for resolving hostnames within small networks. In the past, hackers have exploited this port by conducting Distributed Denial of Service (DDoS) attacks. They send a large number of mDNS queries to UDP port 5353, causing the server to become overwhelmed and unresponsive. Additionally, hackers have used this port for amplification attacks, where a small query can trigger a large response, multiplying the impact on the targeted server. Furthermore, if the mDNS service is poorly configured or left open to the internet, it can be exploited to leak sensitive information about the network and its devices.
