Port 1991
stun-p2 · TCP/UDP
| Range | Registered port (1024–49151) |
|---|---|
| Protocol | TCP/UDP |
| Service | stun-p2 |
Frequently asked questions
What is port 1991 used for?
Port 1991 is registered with the IANA for stun-p2 (TCP/UDP). Description: cisco STUN Priority 2 port.
Is port 1991 a well-known port?
No. Port 1991 is in the range 1024–49151 (registered or user ports). Ordinary programs may open it without root privileges.
How do I check whether port 1991 is open?
Locally on Linux with ss -tulpn | grep ':1991\b', on Windows with netstat -ano | findstr :1991. To test a remote host use Test-NetConnection <host> -Port 1991 in PowerShell or nc -zv <host> 1991 on Linux/macOS.
How do I open port 1991 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 1991/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=1991/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 1991" -Direction Inbound -Protocol TCP -LocalPort 1991 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | stun-p2 | cisco STUN Priority 2 port |
| UDP | stun-p2 | cisco STUN Priority 2 port |