All ports
Port5666/TCP
nrpePort
5666
Protocol
TCP
Category
Registered
Service
nrpe
What is port 5666?
Port 5666/TCP is a Registered port, registered with IANA for specific applications. It is associated with the nrpe service.
Nagios Remote Plugin Executor
Useful commands
nmapnmap -p 5666 -sV example.comnetcatnc -zv example.com 5666curlcurl -v http://example.com:5666/telnettelnet example.com 5666bash(echo > /dev/tcp/example.com/5666) 2>/dev/nullFirewall commands
UFWAllow
sudo ufw allow 5666/tcpDeny
sudo ufw deny 5666/tcpiptablesAllow
sudo iptables -A INPUT -p tcp --dport 5666 -j ACCEPTDeny
sudo iptables -D INPUT -p tcp --dport 5666 -j ACCEPTfirewalldAllow
sudo firewall-cmd --permanent --add-port=5666/tcpWindowsAllow
netsh advfirewall firewall add rule name="Open Port 5666" dir=in action=allow protocol=TCP localport=5666Security 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- Outdated versions with vulnerabilities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 5666/TCP?
Port 5666/TCP is associated with the nrpe service. Nagios Remote Plugin Executor
Is it safe to expose port 5666 to the Internet?
It depends on the service and configuration. Port 5666 (nrpe) 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 5666 is open?
You can use nmap: `nmap -p 5666 -sV example.com`, netcat: `nc -zv example.com 5666`, or the bash command: `(echo > /dev/tcp/example.com/5666) 2>/dev/null && echo "Open" || echo "Closed"`.
How do I open or close port 5666 on my firewall?
On Linux with UFW: `sudo ufw allow 5666/tcp` (open) or `sudo ufw deny 5666/tcp` (close). With iptables: `sudo iptables -A INPUT -p tcp --dport 5666 -j ACCEPT`. On Windows: `netsh advfirewall firewall add rule name="Open Port 5666" dir=in action=allow protocol=TCP localport=5666`.
What applications and services use port 5666?
Port 5666/TCP is used by the nrpe service. Specific uses depend on the software and configuration. Check our related tools section for more information.