Incorrect Nagios "Host UP" alerts

[anandkrishn33]

Hi All,

good day!

Im new to this forum.I have a question/issue which has been troubling lately.Nagiso is sending incorrect HOST UP alerts but the hosts are never DOWN.I have configured my nagios as below.Please help.


contacts.cfg -

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       define contact{
        contact_name                    nagiosadmin             ; Short name of user
        use                             generic-contact         ; Inherit default values from generic-contact template (defined above)
        alias                           Nagios Admin            ; Full name of user
        service_notification_commands   notify-service-by-email
        host_notification_commands      notify-host-by-email
        service_notification_options    w,u,c,r,f,s
        host_notification_options       d,u,r,f,s

commands.cfg:

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define command{
command_name notify-host-by-email
command_line /usr/bin/printf "%b" "***** Nagios  *****\n\nNotification Type: $NOTIFICATIONTYPE$\nHost: $HOSTNAME$\nState: $HOSTSTATE$\nAddress: $HOS
TADDRESS$\nInfo: $HOSTOUTPUT$\n\nDate/Time: $LONGDATETIME$\n" | /product/sendEmail-v1.56/sendEmail -f nagios@****** -s ******:25 -
u "***** $NOTIFICATIONTYPE$ Host Alert: $HOSTNAME$ is $HOSTSTATE$ *****" -t $CONTACTEMAIL$
}

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define command{
command_name notify-service-by-email
command_line /usr/bin/printf "%b" "***** Nagios  *****\n\nNotification Type: $NOTIFICATIONTYPE$\n\nService: $SERVICEDESC$\nHost: $HOSTALIAS$\nAddres
s: $HOSTADDRESS$\nState: $SERVICESTATE$\n\nDate/Time: $LONGDATETIME$\n\nAdditional Info:\n\n$SERVICEOUTPUT$" | /product/sendEmail-v1.56/sendEmail -f nagios@****** -s ******:25 -u "***** $NOTIFICATIONTYPE$ Service Alert: $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$ *****" -t $CONTACTEMAIL$
}

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# 'check_ping' command definition
define command{
        command_name    check_ping
        command_line    $USER1$/check_ping -H $HOSTADDRESS$ -w 300000.0,100% -c 300000.0,100%
        }

hosts.cfg:

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define host{
use                             linux-server
host_name                       HOST1
alias                           HOST1
address                         ******
check_period                    24x7
check_interval                  5
retry_interval                  1
max_check_attempts              10
check_command                   check_ping
notification_period             24x7
notification_interval           30
contact_groups                  admins
}

[dwhitfield]

What version of Nagios Core are you using? Did you install it from repos or did you compile? On what OS (and version) is Nagios running? What is the OS (and version) of the machine you are monitoring? Thanks!

[nozlaf]

if you have check_host_freshness set to 1 and you are doing a lot of checks or have a performance issue with your nagios server, nagios may think the host is down because the check has not been executed fast enough
so check the value of

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 check_host_freshness 

if it is set to 1 see if setting it to 0 makes the issue go away, if it does and you need check host freshness because you use passive host checks consider implementing a ramdisk or other performance magic bullet

[dwhitfield]

Thanks @nozlaf!

On the performance front, you should find https://assets.nagios.com/downloads/nag ... uning.html useful in general.

On ramdisk specifically, you should find https://labs.nagios.com/2012/01/30/nagi ... g-disk-io/ useful.

Also, if you could answer the questions from my earlier post, that would be helpful going forward. Thanks!

[anandkrishn33]

Hi guys thanks for the replies:)

OS -
Linux u1632956000126 2.6.32-431.29.2.el6.x86_64 #1 SMP Sun Jul 27 15:55:46 EDT 2014 x86_64 x86_64 x86_64 GNU/Linux

NAGIOS:
Nagios® Core™
Version 4.2.0

check_host_freshness is for passive checks only ? When i tried setting it up , it is nt allowing.Im not using any passive checks , just normal active 5 min checks.

previously I had this :

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define contact{
        contact_name                    nagiosadmin             ; Short name of user
        use                             generic-contact         ; Inherit default values from generic-contact template (defined above)
        alias                           Nagios Admin            ; Full name of user
        service_notification_commands   notify-service-by-email,notify-host-by-email
        host_notification_commands      notify-host-by-email,notify-service-by-email
        service_notification_options    w,u,c,r,f,s
        host_notification_options       d,u,r,f,s

Now i removed to :

Code: Select all

      define contact{
        contact_name                    nagiosadmin             ; Short name of user
        use                             generic-contact         ; Inherit default values from generic-contact template (defined above)
        alias                           Nagios Admin            ; Full name of user
        service_notification_commands   notify-service-by-email
        host_notification_commands      notify-host-by-email
        service_notification_options    w,u,c,r,f,s
        host_notification_options       d,u,r,f,s

there was double notification for each of host and service checks.

[dwhitfield]

Apologize for the battery of questions, but I want to make sure I have all the information I need.

I'm guessing you installed from source, since I'm not aware of packages for 4.2.0. Is that correct?

Passive checks are definitely going to give you better performance, but right now I don't see a ton of reason why performance would be the issue. I want to rule that out. Is the ping check the only check you are running? Is it just the one host you are checking? What's the RAM and CPU situation? Is Nagios running in a VM?

How close are these machines on the network? What is the network performance like? We can do do some testing on this later if we need to.

Lastly, did you take a look at the performance documentation in my last post?