Port 5353 · mDNS

Port 5353 is mDNS, UDP.

Multicast DNS — zero-config service discovery on local segments. Used by Apple Bonjour, Chromecast, and others.

Palo Alto

Create the service object for this port, then allow the App-ID on it. Restricting the rule to the port's service object keeps the rule working on a non-default port and stops the App-ID matching on other ports. Replace the placeholders with your own rule name and zones.

set service udp-5353 protocol udp port 5353

set rulebase security rules <rule-name> from <from-zone> to <to-zone> source any destination any application mdns service udp-5353 action allow

Risk and exposure

Rated low risk. Even so, only expose this port to the networks and hosts that need it, and keep it patched.

Check it

• Linux ss -ulnp | grep :5353
• nmap nmap -sU -p 5353 <host>

Related ports

• 1900 SSDP / UPnP
• 3702 WS-Discovery

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