We have been using LibreNMS for almost a year now and loving everything about it except one thing. False positive machine/switch/router going down reports. We are using it along side Statseeker and even though Statseeker gives false positives every now and again LMS does it way more often. I am not sure if i have alert rules setup wrong or what but I cannot seem to find alot of documentation on the breakdown of alert rules. We have had it tell us routers, switches and servers are down but we can ping, pull snmp info and remote/ssh into them. Can someone verify I have this alert rule setup properly to tell me that a router is down? I would like it to check in more than one way to verify ie… snmp and icmp not responding.
Whats the latency of those routers/switches?
Does the false positive happens on all devices?
Did you tuned your fping options?
Latency of a ping to just about any device I ping (and I just tried several is between 1.5 and 3 ms.
I have had the false positives on many devices… we are monitoring 193 different devices and I cannot say with any certainty that it has happened on all but it has happened on quite a few that we can verify are actually up and LMS is reporting down. I cannot say one type of device over another either.
I don’t believe I did anything to tune fping… do you have a specific suggestion. The last polling time took 107 seconds. Is this what your referring too @TheGreatDoc?
Well, I was hoping that your issue were a latency one.
What does LNMS to check host before polling is an icmp check, if that fails host is marked as down.
FPing settings are in config.php https://docs.librenms.org/Support/Configuration/#fping.
Your pic is for rrd.
I am looking in my config.php and I have no settings for fping. Should I? Being that the entire polling takes over 1.5 minutes I obviously don’t want to poll every minute. What are the suggestions for having about 200 devices to poll?
Do I want to go with settings like these?
$config['fping'] = "/usr/bin/fping";
$config['fping6'] = "fping6";
$config['fping_options']['timeout'] = 500;
$config['fping_options']['count'] = 3;
$config['fping_options']['interval'] = 500;
Sorry, what I mean is fping is configured in config.php.
If no configuration is found, its uses the defaults one. You can find default values at includes/defaults.inc.php
(Dont modify that file or you will break updates)
Doesnt really matter how many devices you have to tune fping, its more what latency do devices have.
Im trying to remember how was the icmp check (at code) as there is also another thread with same issue (false positives) but Im a bit out of coding for the last few months… Maybe someone else could help us
Yea I found other false positive threads on the forums talking about it but no one seems to have a straight forward answer for my particular problem. Which is why I worded my questions as such. Anyway thanks for responding so fast @TheGreatDoc hopefully someone else might be able to help.