I've deployed a new instance of Nagios on a fresh install of CentOS 7 via the EPEL repository. So the Nagios Core version is 3.5.1.
After installing nagios and nagios-plugins-all (via yum), I've created a number of hosts and service definitions, have tested my configuration with nagios -v /etc/nagios/nagios.cfg, and have Nagios up and running!
Unfortunately, my host checks are failing (although my service checks are working perfectly fine).
Within the Nagios Web GUI / Dashboard, if I drill down into a Host page with the "Host State Information", I see this being reported for "Status Information" (IP address removed):
Status Information: /usr/bin/ping -n -U -w 30 -c 5 {my-host-ip-address}
CRITICAL - Could not interpret output from ping command
So in my troubleshooting, I drilled down into the Nagios Plugins directory (/usr/lib64/nagios/plugins), and ran a test with the check_ping plugin consistent with the way check-host-alive runs the command (see below for my check-host-alive command definition):
./check_ping -H {my-ip-address} -w 3000.0,80% -c 5000.0,100% -p 5
This check_ping command returns the following output:
PING OK - Packet loss = 0%, RTA = 0.63 ms|rta=0.627000ms;3000.000000;5000.000000;0.000000 pl=0%;80;100;0
I haven't changed the definition of how check_ping works, and can confirm that I'm getting a "PING OK" whenever the command is run the same way that check-host-alive runs the command, so I cannot figure out what's going on!
Below are the command definitions for check-host-alive as well as check_ping.
# 'check-host-alive' command definition
define command{
command_name check-host-alive
command_line $USER1$/check_ping -H $HOSTADDRESS$ -w 3000.0,80% -c 5000.0,100% -p 5
}
{snip}
# 'check_ping' command definition
define command{
command_name check_ping
command_line $USER1$/check_ping -H $HOSTADDRESS$ -w $ARG1$ -c $ARG2$ -p 5
}
Any suggestions on how I can fix my check-host-alive command definition to work properly and evaluate the output of check_ping properly?
Edit
Below is the full define host {} template I'm using:
define host {
host_name myers ; The name of this host template
alias Myers
address [redacted]
check_command check-host-alive
contact_groups admins
notifications_enabled 0 ; Host notifications are enabled
event_handler_enabled 1 ; Host event handler is enabled
flap_detection_enabled 1 ; Flap detection is enabled
failure_prediction_enabled 1 ; Failure prediction is enabled
process_perf_data 1 ; Process performance data
retain_status_information 1 ; Retain status information across program restarts
retain_nonstatus_information 1 ; Retain non-status information across program restarts
notification_period 24x7 ; Send host notifications at any time
register 1
max_check_attempts 2
}
Answer
For anyone else who runs into this issue, there's another option than changing permissions on ping. Simply change the host check command to use check_host rather than check_ping. While there are certainly some differences in the functionality, the overall end result is the same.
There are those who will say this isn't a good option because of the ability to range the check_ping command, but it should be remembered that host checks aren't even executed until all service checks for a given host have failed. Anyway, if you're interested in testing throughput, there are MUCH better ways of going about it than relying on ICMP, which is the lowest priority traffic type on a network.
I'm sure the OP is well on to other things by now, but hopefully someone else who has this issue will benefit.