Port 43
nicname · TCP/UDP
| Range | System/well-known port (0–1023) |
|---|---|
| Protocol | TCP/UDP |
| Service | nicname |
Frequently asked questions
What is port 43 used for?
Port 43 is registered with the IANA for nicname (TCP/UDP). Description: Who Is.
Is port 43 a well-known port?
Yes. Port 43 is in the range 0–1023 (system or well-known ports). On Linux and macOS only privileged processes may bind to these ports.
How do I check whether port 43 is open?
Locally on Linux with ss -tulpn | grep ':43\b', on Windows with netstat -ano | findstr :43. To test a remote host use Test-NetConnection <host> -Port 43 in PowerShell or nc -zv <host> 43 on Linux/macOS.
How do I open port 43 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 43/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=43/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 43" -Direction Inbound -Protocol TCP -LocalPort 43 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | nicname | Who Is |
| UDP | nicname | Who Is |