Port 5353: mDNS
Port 5353 is Multicast DNS, used by protocols like Apple's Bonjour and various IoT devices to resolve hostnames on the local network without a DNS server. It only works within a single broadcast domain.
UDPCore servicesUnencrypted by defaultIANA assigned
| Port number | 5353 |
|---|---|
| Service | Multicast DNS |
| Protocol | UDP |
| Category | Core services |
| Default encryption | No |
Security note. Port 5353 is not encrypted by default. Restrict it to trusted networks, or use an encrypted alternative where one exists, to avoid exposing credentials and data in transit.
Frequently asked questions
What is port 5353 used for?
Port 5353 is Multicast DNS, used by protocols like Apple's Bonjour and various IoT devices to resolve hostnames on the local network without a DNS server. It only works within a single broadcast domain.
Is port 5353 TCP or UDP?
Port 5353 (mDNS) uses UDP.
Is port 5353 secure?
Port 5353 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 5353 on my firewall?
Only if you specifically need mDNS. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.