All ports
Port1991/TCP
stun-p2Port
1991
Protocol
TCP
Category
Registered
Service
stun-p2
What is port 1991?
Port 1991/TCP is a Registered port, registered with IANA for specific applications. It is associated with the stun-p2 service.
cisco STUN Priority 2 port
Useful commands
nmapnmap -p 1991 -sV example.comnetcatnc -zv example.com 1991curlcurl -v http://example.com:1991/telnettelnet example.com 1991bash(echo > /dev/tcp/example.com/1991) 2>/dev/nullFirewall commands
UFWAllow
sudo ufw allow 1991/tcpDeny
sudo ufw deny 1991/tcpiptablesAllow
sudo iptables -A INPUT -p tcp --dport 1991 -j ACCEPTDeny
sudo iptables -D INPUT -p tcp --dport 1991 -j ACCEPTfirewalldAllow
sudo firewall-cmd --permanent --add-port=1991/tcpWindowsAllow
netsh advfirewall firewall add rule name="Open Port 1991" dir=in action=allow protocol=TCP localport=1991Security Risks
- Unauthorized access to the service
- Data exposure if the service is unauthenticated
- Outdated versions with vulnerabilities
- Incorrect service configuration
Frequently Asked Questions
What service runs on port 1991/TCP?
Port 1991/TCP is associated with the stun-p2 service. cisco STUN Priority 2 port
Is it safe to expose port 1991 to the Internet?
It depends on the service and configuration. Port 1991 (stun-p2) is a Registered port. If you need to expose it, keep the service updated, use strong authentication, and configure a firewall. It's always recommended to restrict access by IP when possible.
How do I check if port 1991 is open?
You can use nmap: `nmap -p 1991 -sV example.com`, netcat: `nc -zv example.com 1991`, or the bash command: `(echo > /dev/tcp/example.com/1991) 2>/dev/null && echo "Open" || echo "Closed"`.
How do I open or close port 1991 on my firewall?
On Linux with UFW: `sudo ufw allow 1991/tcp` (open) or `sudo ufw deny 1991/tcp` (close). With iptables: `sudo iptables -A INPUT -p tcp --dport 1991 -j ACCEPT`. On Windows: `netsh advfirewall firewall add rule name="Open Port 1991" dir=in action=allow protocol=TCP localport=1991`.
What applications and services use port 1991?
Port 1991/TCP is used by the stun-p2 service. Specific uses depend on the software and configuration. Check our related tools section for more information.