Nagios Support Forum

Posted: **Sat Jan 31, 2026 5:58 am**

Hello,

I am using Nagios Core 4.5.11 on Ubuntu 24.
I am trying to configure Nagios to receive SNMPv3 traps.
I have installed the SNMP packages and all services are running (snmpd, snmptrapd, snmptt).
I have a passive configuration in Nagios that is waiting for traps.
I'm not quite done with the configuration yet, but I can receive test traps from remote hosts in /var/log/snmptrapd.log.

But now I see that the Nagios alert history is flooded every 5 seconds with 6 entries like these, even though the Nagios server is not receiving any traps:

Alert History in Nagios:

Code: Select all

Service Critical[01-31-2026 10:21:59] SERVICE ALERT: ras01;SNMP Traps;CRITICAL;HARD;1;(No output returned from plugin)
Service Critical[01-31-2026 10:21:59] SERVICE ALERT: ras01;SNMP Traps;CRITICAL;HARD;1;(No output returned from plugin)
Service Critical[01-31-2026 10:21:59] SERVICE ALERT: ras01;SNMP Traps;CRITICAL;HARD;1;(No output returned from plugin)
Service Critical[01-31-2026 10:21:59] SERVICE ALERT: ras01;SNMP Traps;CRITICAL;HARD;1;(No output returned from plugin)
Service Critical[01-31-2026 10:21:59] SERVICE ALERT: ras01;SNMP Traps;CRITICAL;HARD;1;(No output returned from plugin)
Service Critical[01-31-2026 10:21:59] SERVICE ALERT: ras01;SNMP Traps;CRITICAL;HARD;1;(No output returned from plugin)

Service Critical[01-31-2026 10:21:54] SERVICE ALERT: ras01;SNMP Traps;CRITICAL;HARD;1;(No output returned from plugin)
Service Critical[01-31-2026 10:21:54] SERVICE ALERT: ras01;SNMP Traps;CRITICAL;HARD;1;(No output returned from plugin)
Service Critical[01-31-2026 10:21:54] SERVICE ALERT: ras01;SNMP Traps;CRITICAL;HARD;1;(No output returned from plugin)
Service Critical[01-31-2026 10:21:54] SERVICE ALERT: ras01;SNMP Traps;CRITICAL;HARD;1;(No output returned from plugin)
Service Critical[01-31-2026 10:21:54] SERVICE ALERT: ras01;SNMP Traps;CRITICAL;HARD;1;(No output returned from plugin)
Service Critical[01-31-2026 10:21:54] SERVICE ALERT: ras01;SNMP Traps;CRITICAL;HARD;1;(No output returned from plugin)

I have changed "check_freshness" to 0, but the problem persists.

How can I stop these messages or increase the intervall?

#/usr/local/nagios/etc/servers/ras01.cfg

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#
define host {
    use             generic-host       
    host_name       ras01
    address         192.168.178.25
    alias           USV
    max_check_attempts 1
    check_interval     15  
    retry_interval     1  
    notification_period     24x7
}
define service {
    use                     trap-service
    host_name               ras01
    service_description     SNMP Traps
    check_command           check_dummy!0!"Waiting for Traps"
    active_checks_enabled   0
    passive_checks_enabled  1
    check_period            24x7
    max_check_attempts      1
    check_interval          60 
    retry_interval          1 
    notification_interval   0
    check_freshness         0
    freshness_threshold     3600
    flap_detection_enabled  0
    notification_options    w,u,c,r
    notifications_enabled   1
    register                1
}

# /usr/local/nagios/objects/templates.cfg

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#
define service{
     name                    trap-service
     register                0
     use                     generic-service
     is_volatile             1
     active_checks_enabled   0
     passive_checks_enabled  1
     check_command           check_dummy!0!"Waiting for traps"
     max_check_attempts      1  
     check_interval          5  
     retry_interval          1  
     flap_detection_enabled  0
     notifications_enabled   1
     notification_interval   0
     notification_period     24x7
     notification_options    w,u,c,r
     contact_groups          admins
}

#/etc/snmp/snmptrapd.conf

Code: Select all

#
#here I create SNMPv3 users and call a test handler
#This test handler starts successfully when a test trap arrives and writes information to a temporary test file, but does not send anything to nagios.cmd.
#
traphandle default /usr/local/nagios/libexec/eventhandlers/debug_trap.sh

Posted: **Mon Feb 02, 2026 2:28 pm**

As far as I know a passive check shouldn't have check or retry intervals. Since the check appears to be running it looks like check_dummy isn't being found. I'd run the check manually from the nagios web page to test. Also set the intervals correctly.
I'd get rid of the template and just have the service, but that's me. Once the issue is resolved, the template can be used.

Posted: **Wed Feb 04, 2026 2:35 am**

Nagios is behaving as designed based on its current configuration, but that configuration is incomplete or incorrect for SNMP trap handling. The flooding alerts are a symptom of Nagios waiting for passive results that are never delivered, Poor Bunny not evidence of real SNMP trap activity. Properly finalizing the passive check setup and ensuring snmptt correctly forwards traps to Nagios will resolve the issue.

Posted: **Thu Feb 05, 2026 10:53 am**

sellan wrote: ↑Wed Feb 04, 2026 2:35 am Nagios is behaving as designed based on its current configuration, but that configuration is incomplete or incorrect for SNMP trap handling.

Thanks for the reply. In my case, the lack of traps is considered “OK,” so I'm wondering how I can suppress these messages. I was hoping there would be a switch in a configuration file, but I can't figure out where to find it.

Posted: **Thu Feb 05, 2026 1:14 pm**

You can't figure out how to find the things I mentioned?

Nagios Support Forum

Flooding Alert history

Flooding Alert history

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Re: Flooding Alert history