Nagios Support Forum

Hi Team,

Please explain the complete details about Ping Monitoring through Nagios XI. How does it work from backend as well and where are the logs getting generated during Ping Monitoring.

We request you to please help us with the answers with the below questions:
1. If the Ping Monitoring is set for every 1 min in alert settings for host then does Nagios Pings the Host every 1 min once or for continuous 1 min and then stops for 1 min and then continuously pings for 1 min.
2. How does the Nagios understand about flap detection that the state of the host is flapping.
3. we understood from ping that it transmits 5 packets for 1 ping and waits for the reply if in case all the 5 packets are received the host is said to be up , so when does it send the Host down alert ?

We want to address the below scenario:

We have backups scheduled during entire night for all the servers configured on Nagios XI. During backup activity or migration activity there is a possibility that some packets might be dropped ( say for e.g 5 to 10 packets are dropped) for which Nagios is sending Host Down Alert but rather is Host is up so in this way we are getting huge amount of false alerts during this activity.

Now we cannot suppress the alerts as in case if the host really goes down we wont able to catch it so we dont want Nagios XI to send the Host Down Alert for only 5 to 10 packets drop. Can you please help us how to achieve this.

Also please let us know how we can arrange a Call with Nagios Support Team to explain more on this.

I've attached a screenshot of a default PING service check. Please note that your configuration may vary so it is best to check and provide screenshots when possible.

1. When the check is run it will run 1 per minute not continuously for a minute.
2. https://assets.nagios.com/downloads/nag ... pping.html has details on flap detection.
3. The check will send 5 ping requests(-p 5). If the average return time average is larger than 100ms or 1 to 2 ping requests do not get a response, then a WARNING is triggered. If the return time average is larger than 500ms or 3 or more ping requests do not get a response, then a CRITICAL is triggered.

If you want to increase the number of ping requests that are sent(but only for this or other specific hosts) then you would need to create a new command under Configuration > Core Config Manager > Commands > Commands, with a definition that looks like:
you would then edit the service to use the new command. The $ARG3$ field would be used to control how many ping requests to send.

And if you have phone support you can call us at the number listed on https://www.nagios.com/contact/. Please have the last 6 characters of your license or your customer ID number ready so we can confirm phone support.

Hi Team,

Thanks. Can you also please let us know as how to increase the default number of pings( 5) which Nagios will do to check the Host Status to another integer figure say 20.

As suggested by you to create a new command we created and configured to a host but Nagios is still making those default "5" number of pings to the host.

Obviously creating new service will help achieve this but we are interested in making Nagios change the number of pings requests it makes to 20.

If your hosts/services are using that check_ping command you screenshot you can go to Configure > Core Config Manager > Commands:
- Search for check_ping
- Edit the command and change -p 5 to -p 20
- Save and Apply Configuration

I personally would leave it at 5 and then increase your max_check_attempts value on the services/hosts instead as increasing all your ping checks from 5 to 20 will likely have a negative performance impact (longer running checks = more time consuming resources). I would look at the output of the top command for a few minutes to see what your current load is on your system before changing it so you can get an idea of whether the impact is substantial (the load is bolded below) after changing it:

[root@xid ~]# top
top - 12:42:59 up 1:22, 2 users, load average: 0.21, 0.52, 0.63
Tasks: 162 total, 1 running, 161 sleeping, 0 stopped, 0 zombie
%Cpu(s): 6.8 us, 1.7 sy, 0.0 ni, 91.5 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st