NRPEServer

A server that listens for incoming NRPE connection and processes incoming requests.

Enable module

To enable this module and and allow using the commands you need to ass NRPEServer = enabled to the [/modules] section in nsclient.ini:

[/modules]
NRPEServer = enabled

Configuration

Path / Section	Description
/settings/default	Default values
/settings/NRPE/server	NRPE Server

Default values

Default values used in other config sections.

Key	Default Value	Description
allowed hosts	127.0.0.1	ALLOWED HOSTS
bind to		BIND TO ADDRESS
cache allowed hosts	true	CACHE ALLOWED HOSTS
encoding		NRPE PAYLOAD ENCODING
inbox	inbox	INBOX
password		Password
socket queue size	0	LISTEN QUEUE
thread pool	10	THREAD POOL
timeout	30	TIMEOUT

# Default values used in other config sections.
[/settings/default]
allowed hosts=127.0.0.1
cache allowed hosts=true
inbox=inbox
socket queue size=0
thread pool=10
timeout=30

ALLOWED HOSTS

A comma separated list of allowed hosts. You can use netmasks (/ syntax) or * to create ranges.

Key	Description
Path:	/settings/default
Key:	allowed hosts
Default value:	`127.0.0.1`
Used by:	CheckMKServer, NRPEServer, NSCAServer, NSClientServer, WEBServer

Sample:

[/settings/default]
# ALLOWED HOSTS
allowed hosts=127.0.0.1

BIND TO ADDRESS

Allows you to bind server to a specific local address. This has to be a dotted ip address not a host name. Leaving this blank will bind to all available IP addresses.

Key	Description
Path:	/settings/default
Key:	bind to
Default value:	N/A
Used by:	CheckMKServer, NRPEServer, NSCAServer, NSClientServer, WEBServer

Sample:

[/settings/default]
# BIND TO ADDRESS
bind to=

CACHE ALLOWED HOSTS

If host names (DNS entries) should be cached, improves speed and security somewhat but won't allow you to have dynamic IPs for your Nagios server.

Key	Description
Path:	/settings/default
Key:	cache allowed hosts
Default value:	`true`
Used by:	CheckMKServer, NRPEServer, NSCAServer, NSClientServer, WEBServer

Sample:

[/settings/default]
# CACHE ALLOWED HOSTS
cache allowed hosts=true

NRPE PAYLOAD ENCODING

Key	Description
Path:	/settings/default
Key:	encoding
Advanced:	Yes (means it is not commonly used)
Default value:	N/A
Used by:	CheckMKServer, NRPEServer, NSCAServer, NSClientServer, WEBServer

Sample:

[/settings/default]
# NRPE PAYLOAD ENCODING
encoding=

INBOX

The default channel to post incoming messages on

Key	Description
Path:	/settings/default
Key:	inbox
Default value:	`inbox`
Used by:	CheckMKServer, NRPEServer, NSCAServer, NSClientServer, WEBServer

Sample:

[/settings/default]
# INBOX
inbox=inbox

Password

Password used to authenticate against server

Key	Description
Path:	/settings/default
Key:	password
Default value:	N/A
Used by:	CheckMKServer, NRPEServer, NSCAServer, NSClientServer, WEBServer

Sample:

[/settings/default]
# Password
password=

LISTEN QUEUE

Number of sockets to queue before starting to refuse new incoming connections. This can be used to tweak the amount of simultaneous sockets that the server accepts.

Key	Description
Path:	/settings/default
Key:	socket queue size
Advanced:	Yes (means it is not commonly used)
Default value:	`0`
Used by:	CheckMKServer, NRPEServer, NSCAServer, NSClientServer, WEBServer

Sample:

[/settings/default]
# LISTEN QUEUE
socket queue size=0

THREAD POOL

Key	Description
Path:	/settings/default
Key:	thread pool
Advanced:	Yes (means it is not commonly used)
Default value:	`10`
Used by:	CheckMKServer, NRPEServer, NSCAServer, NSClientServer, WEBServer

Sample:

[/settings/default]
# THREAD POOL
thread pool=10

TIMEOUT

Timeout when reading packets on incoming sockets. If the data has not arrived within this time we will bail out.

Key	Description
Path:	/settings/default
Key:	timeout
Default value:	`30`
Used by:	CheckMKServer, NRPEServer, NSCAServer, NSClientServer, WEBServer

Sample:

[/settings/default]
# TIMEOUT
timeout=30

NRPE Server

Section for NRPE (NRPEServer.dll) (check_nrpe) protocol options.

Key	Default Value	Description
allow arguments	false	COMMAND ARGUMENT PROCESSING
allow nasty characters	false	COMMAND ALLOW NASTY META CHARS
allowed ciphers	ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH	ALLOWED CIPHERS
allowed hosts	127.0.0.1	ALLOWED HOSTS
bind to		BIND TO ADDRESS
ca	${certificate-path}/ca.pem	CA
cache allowed hosts	true	CACHE ALLOWED HOSTS
certificate	${certificate-path}/certificate.pem	SSL CERTIFICATE
certificate format	PEM	CERTIFICATE FORMAT
certificate key		SSL CERTIFICATE
dh	${certificate-path}/nrpe_dh_2048.pem	DH KEY
encoding		NRPE PAYLOAD ENCODING
extended response	true	EXTENDED RESPONSE
insecure	false	ALLOW INSECURE CHIPHERS and ENCRYPTION
payload length	1024	PAYLOAD LENGTH
performance data	true	PERFORMANCE DATA
port	5666	PORT NUMBER
socket queue size	0	LISTEN QUEUE
ssl options		VERIFY MODE
thread pool	10	THREAD POOL
timeout	30	TIMEOUT
tls version	tlsv1.2+	TLS version to use
use ssl	true	ENABLE SSL ENCRYPTION
verify mode	none	VERIFY MODE

# Section for NRPE (NRPEServer.dll) (check_nrpe) protocol options.
[/settings/NRPE/server]
allow arguments=false
allow nasty characters=false
allowed ciphers=ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH
allowed hosts=127.0.0.1
ca=${certificate-path}/ca.pem
cache allowed hosts=true
certificate=${certificate-path}/certificate.pem
certificate format=PEM
dh=${certificate-path}/nrpe_dh_2048.pem
extended response=true
insecure=false
payload length=1024
performance data=true
port=5666
socket queue size=0
thread pool=10
timeout=30
tls version=tlsv1.2+
use ssl=true
verify mode=none

COMMAND ARGUMENT PROCESSING

This option determines whether or not the we will allow clients to specify arguments to commands that are executed.

Key	Description
Path:	/settings/NRPE/server
Key:	allow arguments
Default value:	`false`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# COMMAND ARGUMENT PROCESSING
allow arguments=false

COMMAND ALLOW NASTY META CHARS

This option determines whether or not the we will allow clients to specify nasty (as in |`&><'"\[]{}) characters in arguments.

Key	Description
Path:	/settings/NRPE/server
Key:	allow nasty characters
Default value:	`false`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# COMMAND ALLOW NASTY META CHARS
allow nasty characters=false

ALLOWED CIPHERS

The chipers which are allowed to be used. The default here will differ is used in "insecure" mode or not. check_nrpe uses a very old chipers and should preferably not be used. For details of chipers please see the OPEN ssl documentation: https://www.openssl.org/docs/apps/ciphers.html

Key	Description
Path:	/settings/NRPE/server
Key:	allowed ciphers
Advanced:	Yes (means it is not commonly used)
Default value:	`ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# ALLOWED CIPHERS
allowed ciphers=ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH

ALLOWED HOSTS

A comma separated list of allowed hosts. You can use netmasks (/ syntax) or * to create ranges. parent for this key is found under: /settings/default this is marked as advanced in favor of the parent.

Key	Description
Path:	/settings/NRPE/server
Key:	allowed hosts
Advanced:	Yes (means it is not commonly used)
Default value:	`127.0.0.1`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# ALLOWED HOSTS
allowed hosts=127.0.0.1

BIND TO ADDRESS

Allows you to bind server to a specific local address. This has to be a dotted ip address not a host name. Leaving this blank will bind to all available IP addresses. parent for this key is found under: /settings/default this is marked as advanced in favor of the parent.

Key	Description
Path:	/settings/NRPE/server
Key:	bind to
Advanced:	Yes (means it is not commonly used)
Default value:	N/A
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# BIND TO ADDRESS
bind to=

CA

Key	Description
Path:	/settings/NRPE/server
Key:	ca
Advanced:	Yes (means it is not commonly used)
Default value:	`${certificate-path}/ca.pem`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# CA
ca=${certificate-path}/ca.pem

CACHE ALLOWED HOSTS

If host names (DNS entries) should be cached, improves speed and security somewhat but won't allow you to have dynamic IPs for your Nagios server. parent for this key is found under: /settings/default this is marked as advanced in favor of the parent.

Key	Description
Path:	/settings/NRPE/server
Key:	cache allowed hosts
Advanced:	Yes (means it is not commonly used)
Default value:	`true`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# CACHE ALLOWED HOSTS
cache allowed hosts=true

SSL CERTIFICATE

Key	Description
Path:	/settings/NRPE/server
Key:	certificate
Advanced:	Yes (means it is not commonly used)
Default value:	`${certificate-path}/certificate.pem`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# SSL CERTIFICATE
certificate=${certificate-path}/certificate.pem

CERTIFICATE FORMAT

Key	Description
Path:	/settings/NRPE/server
Key:	certificate format
Advanced:	Yes (means it is not commonly used)
Default value:	`PEM`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# CERTIFICATE FORMAT
certificate format=PEM

SSL CERTIFICATE

Key	Description
Path:	/settings/NRPE/server
Key:	certificate key
Advanced:	Yes (means it is not commonly used)
Default value:	N/A
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# SSL CERTIFICATE
certificate key=

DH KEY

Key	Description
Path:	/settings/NRPE/server
Key:	dh
Advanced:	Yes (means it is not commonly used)
Default value:	`${certificate-path}/nrpe_dh_2048.pem`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# DH KEY
dh=${certificate-path}/nrpe_dh_2048.pem

NRPE PAYLOAD ENCODING

parent for this key is found under: /settings/default this is marked as advanced in favor of the parent.

Key	Description
Path:	/settings/NRPE/server
Key:	encoding
Advanced:	Yes (means it is not commonly used)
Default value:	N/A
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# NRPE PAYLOAD ENCODING
encoding=

EXTENDED RESPONSE

Send more then 1 return packet to allow response to go beyond payload size (requires modified client if legacy is true this defaults to false).

Key	Description
Path:	/settings/NRPE/server
Key:	extended response
Default value:	`true`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# EXTENDED RESPONSE
extended response=true

ALLOW INSECURE CHIPHERS and ENCRYPTION

Only enable this if you are using legacy check_nrpe client.

Key	Description
Path:	/settings/NRPE/server
Key:	insecure
Default value:	`false`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# ALLOW INSECURE CHIPHERS and ENCRYPTION
insecure=false

PAYLOAD LENGTH

Length of payload to/from the NRPE agent. This is a hard specific value so you have to "configure" (read recompile) your NRPE agent to use the same value for it to work.

Key	Description
Path:	/settings/NRPE/server
Key:	payload length
Advanced:	Yes (means it is not commonly used)
Default value:	`1024`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# PAYLOAD LENGTH
payload length=1024

PERFORMANCE DATA

Send performance data back to nagios (set this to 0 to remove all performance data).

Key	Description
Path:	/settings/NRPE/server
Key:	performance data
Advanced:	Yes (means it is not commonly used)
Default value:	`true`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# PERFORMANCE DATA
performance data=true

PORT NUMBER

Port to use for NRPE.

Key	Description
Path:	/settings/NRPE/server
Key:	port
Default value:	`5666`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# PORT NUMBER
port=5666

LISTEN QUEUE

Number of sockets to queue before starting to refuse new incoming connections. This can be used to tweak the amount of simultaneous sockets that the server accepts. parent for this key is found under: /settings/default this is marked as advanced in favor of the parent.

Key	Description
Path:	/settings/NRPE/server
Key:	socket queue size
Advanced:	Yes (means it is not commonly used)
Default value:	`0`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# LISTEN QUEUE
socket queue size=0

VERIFY MODE

Comma separated list of verification flags to set on the SSL socket.

default-workarounds Various workarounds for what I understand to be broken ssl implementations no-sslv2 Do not use the SSLv2 protocol (prefer tls version instead). no-sslv3 Do not use the SSLv3 protocol (prefer tls version instead). no-tlsv1 Do not use the TLSv1 protocol (prefer tls version instead). no-tlsv1_1 Do not use the TLSv1.1 protocol (prefer tls version instead). no-tlsv1_2 Do not use the TLSv1.2 protocol (prefer tls version instead). no-tlsv1_3 Do not use the TLSv1.3 protocol (prefer tls version instead). single-dh-use Always create a new key when using temporary/ephemeral DH parameters. This option must be used to prevent small subgroup attacks, when the DH parameters were not generated using "strong" primes (e.g. when using DSA-parameters).

Key	Description
Path:	/settings/NRPE/server
Key:	ssl options
Advanced:	Yes (means it is not commonly used)
Default value:	N/A
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# VERIFY MODE
ssl options=

THREAD POOL

parent for this key is found under: /settings/default this is marked as advanced in favor of the parent.

Key	Description
Path:	/settings/NRPE/server
Key:	thread pool
Advanced:	Yes (means it is not commonly used)
Default value:	`10`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# THREAD POOL
thread pool=10

TIMEOUT

Timeout when reading packets on incoming sockets. If the data has not arrived within this time we will bail out. parent for this key is found under: /settings/default this is marked as advanced in favor of the parent.

Key	Description
Path:	/settings/NRPE/server
Key:	timeout
Advanced:	Yes (means it is not commonly used)
Default value:	`30`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# TIMEOUT
timeout=30

TLS version to use

Valid options are tlsv1.3, tlsv1.2, tlsv1.1, tlsv1.0, sslv3 as well as tlsv1.3+, tlsv1.2+, tlsv1.1+, tlsv1.0+, sslv3+ (Which uses the version mentioned and above)

Key	Description
Path:	/settings/NRPE/server
Key:	tls version
Advanced:	Yes (means it is not commonly used)
Default value:	`tlsv1.2+`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# TLS version to use
tls version=tlsv1.2+

ENABLE SSL ENCRYPTION

This option controls if SSL should be enabled.

Key	Description
Path:	/settings/NRPE/server
Key:	use ssl
Default value:	`true`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# ENABLE SSL ENCRYPTION
use ssl=true

VERIFY MODE

Comma separated list of verification flags to set on the SSL socket.

none The server will not send a client certificate request to the client, so the client will not send a certificate. peer The server sends a client certificate request to the client and the certificate returned (if any) is checked. fail-if-no-cert if the client did not return a certificate, the TLS/SSL handshake is immediately terminated. This flag must be used together with peer. peer-cert Alias for peer and fail-if-no-cert. workarounds Various bug workarounds. single Always create a new key when using tmp_dh parameters. client-once Only request a client certificate on the initial TLS/SSL handshake. This flag must be used together with verify-peer

Key	Description
Path:	/settings/NRPE/server
Key:	verify mode
Advanced:	Yes (means it is not commonly used)
Default value:	`none`
Used by:	NRPEServer

Sample:

[/settings/NRPE/server]
# VERIFY MODE
verify mode=none