Multicast DNS Responder IPC

MDNSResponder is a service that implements multicast DNS (mDNS) to resolve hostnames to IP addresses within local networks. It is commonly used in environments where traditional DNS servers are not available. This service is essential for devices like printers and smart home devices to discover each other on the same network.

What is Multicast DNS Responder IPC

MDNSResponder is a service that implements multicast DNS (mDNS), which is a protocol used to resolve hostnames to IP addresses within small networks that do not have a local DNS server. This service is particularly useful in home and small office networks where devices need to discover each other without manual configuration.

The mDNS protocol works by sending DNS-like queries to a special multicast address, allowing devices to respond with their own hostname and IP address. This makes it easier for devices like printers, smart home devices, and other networked gadgets to find each other and communicate seamlessly.

MDNSResponder is often found in Apple products, where it is part of the Bonjour service, but it is also used in other operating systems and devices. The service has been around for many years and has become a standard for local network discovery. However, it is important to manage and secure this service properly to avoid potential security risks.

Multicast DNS Responder IPC runs on TCP and UDP port 5354 and is official IANA port.

Security risk

If port 5354 is open and the MDNSResponder service is running, it could expose the network to potential attacks. Malicious actors could exploit vulnerabilities in the mDNS protocol to gain unauthorized access to network resources or to perform denial-of-service attacks. It is crucial to ensure that this service is properly secured and monitored.

In our UFW tutorial you can follow instructions how you can configure UFW to close port 5354. Use StackChanges to monitor if the Multicast DNS Responder IPC port is closed and stays closed. StackChanges will send an alert if port 5354 is open again.