Port 43 — WHOIS

TCP · Port 43/TCP is used for the WHOIS service, which allows users to query databases of domain name registrars and Internet Service Providers (ISPs) for information about domain names, IP addresses, and other network resources. This port is essential for maintaining accurate records of network ownership and management. Its security relevance lies in its role as a critical infrastructure component.

Port Number: 43
Service Name: WHOIS
Protocol: TCP
Common Software: jwhois, whois daemon

Security Notes

Review IANA registry for port 43 usage. Apply principle of least privilege - only open ports that are required.

FAQ

What is port 43 used for?

Port 43 is used for WHOIS. Port 43/TCP is used for the WHOIS service, which allows users to query databases of domain name registrars and Internet Service Providers (ISPs) for information about domain names, IP addresses, and other network resources. This port is essential for maintaining accurate records of network ownership and management. Its security relevance lies in its role as a critical infrastructure component. Common software: jwhois, whois daemon.

Is port 43 dangerous to leave open?

Review IANA registry for port 43 usage. Apply principle of least privilege - only open ports that are required.

How do I check if port 43 is open?

Use nmap: nmap -p 43 <target> or check locally: ss -tlnp | rg 43