Snmptrapd is working but traps do not show in device logs

Hello, I have installed LibreNMS and am having an issue with SNMP traps at the moment. I was able to configure everything and am receiving the traps on the system and they show in the snmptrapd logs. The issue is that I cannot seem to get them to show in the individual logs for a device in LibreNMS itself. I am sure that it is something simple that I am overlooking, but I just can’t seem to find it.

LibreNMS is installed on a CentOS 8.5 server and here are the related configuration files.

/etc/snmp/snmptrapd.conf

disableAuthorization yes
authCommunity log,execute,net COMMUNITYSTRING
traphandle default /opt/librenms/snmptrap.php

/usr/lib/systemd/system/snmptrapd.service

[Unit]
Description=Simple Network Management Protocol (SNMP) Trap Daemon.
After=syslog.target network-online.target

[Service]
Type=notify
Environment=OPTIONS="-Lsd"
EnvironmentFile=-/etc/sysconfig/snmptrapd
ExecStart=/usr/sbin/snmptrapd $OPTIONS -f -m ALL -M /opt/librenms/mibs -tLf /var/log/snmptrap/traps.log
ExecReload=/bin/kill -HUP $MAINPID

[Install]
WantedBy=multi-user.target

config.php

#snmptrap Event Logging
$config[‘snmptraps’][‘eventlog’] = ‘all’;
$config[‘snmptraps’][‘eventlog_detailed’] = ‘true’;

Then on the LibreNMS server, I run the following test snmptrap command:

snmptrap -v 2c -c public localhost ‘’ 1.3.6.1.4.1.8072.2.3.0.1 1.3.6.1.4.1.8072.2.3.2.1 i 123456

Then it shows the following in the snmptrapd logs /var/log/snmptrap/traps.log

NET-SNMP version 5.8
2021-12-14 09:01:48 localhost [UDP: [127.0.0.1]:59257->[127.0.0.1]:162]:
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (8681570) 1 day, 0:06:55.70 SNMPv2-MIB::snmpTrapOID.0 = OID: NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatNotification NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatRate = INTEGER: 123456

But after that, it never shows in the Log for the LibreNMS device in the LibreNMS server. Thanks for your help and let me know if I can provide any other information.

Checking in to see if anyone has any ideas or needs any more information from me. Thanks.

Still struggling to find a solution, if anyone has an idea. Thanks.

I did find a little more information. It seems to be a permissions issue with the snmptrapd service and the LibreNMS log file. When I view the systemctrl status of snmptrapd after a snmp trap comes in it has the following error:

The stream or file “/opt/librenms/logs/librenms.log” could not be opened in append mode: failed to open stream: Permission denied

I have tried to change the permissions to the file to 777 and it still gives the permission error. The file is owned by librenms:librenms and the service is run by root.

Any thoughts on this additional information? Thanks.

It appears to be an SELinux issue but I am not sure what yet. If I set setenforce 0 then it works fine and the trap is added to the device event log.

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