Is port 5666 (NRPE (Nagios Remote Plugin Executor)) dangerous?

Port 5666 is classified as medium risk. It is commonly exposed but consider using encrypted alternatives where available and monitor activity.

Should port 5666 be open on my firewall?

Port 5666 can be open but should be monitored closely. Keep the service updated and prefer encrypted alternatives where available.

What transport protocol does port 5666 use?

Port 5666 (NRPE (Nagios Remote Plugin Executor)) uses the TCP transport protocol and falls under the System & Infrastructure category.

:5666 (TCP)

NRPE (Nagios Remote Plugin Executor)

Medium Risk

TCP — 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.

Related Ports — System & Infrastructure

0 Reserved 1 TCPMUX 2 Management Utility 3 CompressNET 4 Unassigned 5 RJE 6 Unassigned 7 Echo

Related Terms

Bandwidth Latency Packet Loss Ping Throughput ASN