5666
NRPE (Nagios Remote Plugin Executor)
Medium RiskTCP — System & Infrastructure
Port Overview
Port Number
5666
Service Name
NRPE (Nagios Remote Plugin Executor)
Transport Protocol
TCP
Category
System & Infrastructure
Security Risk
Medium
Port Range
Registered (1024-49151)
What is Port 5666?
Port 5666 is used by NRPE (Nagios Remote Plugin Executor), an agent that allows Nagios and compatible monitoring systems to execute monitoring plugins on remote Linux/Unix hosts. Nagios checks server health metrics like CPU, memory, and disk usage through NRPE. Misconfigured NRPE allowing command arguments can be exploited for remote command execution.
TCP
System & Infrastructure
Commonly Used
Security Considerations
Port 5666 (NRPE (Nagios Remote Plugin Executor)) is classified as medium risk. While this service is commonly exposed, consider using encrypted alternatives where available.
Recommendation: Keep the service updated. Monitor logs for unusual activity.