Port 42 · WINS

Port 42 is WINS, TCP and UDP.

Windows Internet Name Service — legacy NetBIOS name-to-IP resolution. Replaced by DNS. Only relevant in older Windows environments.

Palo Alto

Create the service objects 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 tcp-42 protocol tcp port 42
set service udp-42 protocol udp port 42

set rulebase security rules <rule-name> from <from-zone> to <to-zone> source any destination any application wins service [ tcp-42 udp-42 ] action allow

Risk and exposure

Rated medium risk. Restrict this port to the sources that need it and keep the service patched; avoid exposing it to the whole internet unless the service is meant to be public.

Check it

• Linux ss -tlnp | grep :42
• Linux ss -ulnp | grep :42
• PowerShell Test-NetConnection <host> -Port 42
• nmap nmap -p 42 <host>
• nmap nmap -sU -p 42 <host>

Related ports

• 137 NetBIOS Name Service
• 138 NetBIOS Datagram
• 139 NetBIOS Session
• 53 DNS
• 19 Chargen
• 23 Telnet

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