Port 31
msg-auth · TCP/UDP
| Range | System/well-known port (0–1023) |
|---|---|
| Protocol | TCP/UDP |
| Service | msg-auth |
Frequently asked questions
What is port 31 used for?
Port 31 is registered with the IANA for msg-auth (TCP/UDP). Description: MSG Authentication.
Is port 31 a well-known port?
Yes. Port 31 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 31 is open?
Locally on Linux with ss -tulpn | grep ':31\b', on Windows with netstat -ano | findstr :31. To test a remote host use Test-NetConnection <host> -Port 31 in PowerShell or nc -zv <host> 31 on Linux/macOS.
How do I open port 31 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 31/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=31/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 31" -Direction Inbound -Protocol TCP -LocalPort 31 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | msg-auth | MSG Authentication |
| UDP | msg-auth | MSG Authentication |