This KB article describes why you are seeing the following error message on your Nagios server when the check_nrpe plugin is run:
Nov 28 08:51:34 office_itx_gentoo check_nrpe: Remote 10.25.11.3 does not support Version 3 Packets
Depending on your logging daemon this message could be logged in /var/log/messages or /var/log/syslog.
When the NRPE v3 client first establishes a connection, it tries with the v3 packet. This results in the older client rejecting the request. Upon receiving the rejected request the plugin will then attempt to connect with the v2 packet. This request will succeed however errors are produced in the log on the client and the Nagios server. NSClient++ and NRPE before 3 do not support the v3 packet type.
These KB articles provide more detailed information:
Documentation - Packet Size Explained
Documentation - NRPE v3 Compatibility With Previous Versions
Resolution #1
One method to prevent this message from being logged is to force the check_nrpe plugin to connecting with a v2 packet.
check_nrpe -2 -H 10.25.11.3
This could be defined in your Nagios command definition or on the service checks themselves.
Resolution #2
You could also configure rsyslog on your Nagios server to discard these messages, preventing them from being logged. The following steps are for RHEL / CentOS, if you use a different OS then the file locations and daemon commands could be slightly different.
Establish a terminal session to your Nagios server as the root user. Edit the /etc/rsyslog.conf file in the vi editor by executing the following command:
vi /etc/rsyslog.conf
When using the vi editor, to make changes press i on the keyboard first to enter insert mode. Press Esc to exit insert mode.
Add the following line directly under the #### RULES #### line:
#### RULES ####
:msg, contains, "does not support Version 3 Packets" ~
When you have finished, save the changes in vi by typing:
:wq
and press Enter.
You need to restart the rsyslog service using one of the commands below:
RHEL/CentOS 5.x/6.x
service rsyslog restart
RHEL/CentOS 7.x
systemctl restart rsyslog.service
Once you've made these changes the message will no longer be logged.
Resolution #3
Another method to prevent this message from being logged is to force the check_nrpe plugin to disable logging to syslog with the -D option.
check_nrpe -D -H 10.25.11.3
This could be defined in your Nagios command definition or on the service checks themselves.
Final Thoughts
For any support related questions please visit the Nagios Support Forums at:
http://support.nagios.com/forum/
Article ID: 786
Created On: Mon, Nov 27, 2017 at 3:54 PM
Last Updated On: Mon, Nov 15, 2021 at 3:36 PM
Authored by: tlea
Online URL: https://support.nagios.com/kb/article/nrpe-remote-does-not-support-version-3-packets-786.html