Port 43: WHOIS
Port 43 is WHOIS, the protocol registrars and registries use to answer queries about domain name and IP address ownership. Command-line whois clients and lookup websites both connect on this port.
TCPLegacy protocolsUnencrypted by defaultIANA assigned
| Port number | 43 |
|---|---|
| Service | WHOIS protocol |
| Protocol | TCP |
| Category | Legacy protocols |
| Default encryption | No |
Security note. Port 43 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 43 used for?
Port 43 is WHOIS, the protocol registrars and registries use to answer queries about domain name and IP address ownership. Command-line whois clients and lookup websites both connect on this port.
Is port 43 TCP or UDP?
Port 43 (WHOIS) uses TCP.
Is port 43 secure?
Port 43 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 43 on my firewall?
Only if you specifically need WHOIS. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.