Hosts going up and down constantly

[ecomchris]

Good Day

I am having issues with a zabbix setup. We have a fairly large (relative to all our other zabbix instances) with about 1400 hosts all being monitored via icmp. There are various hosts also being monitored via SNMP so we have a total of around 3900 items. The server recently crashed and we migrated the zabbix from Centos 7 to Ubuntu 24.04. Zabbix is working and all data has been migrated however all my hosts are constantly going up and down, I never have more than about 900 hosts online at a time.

My hosts being monitored via SNMP don't have any issues except for the ICMP data showing that the host is unreachable.

I have increased StartPingers, StartPollers, StartCache etc. and this makes no difference. I can get a "better looking" system by increasing the update time on the ICMP item but this is not a proper fix.

When a host shows down on zabbix i am able to ping it from the server via command line with no packet loss and no latency.

Can someone please assist with a setting we are missing, this seems like a "limitation" on the number of actual pings the server can have running at the same time but I need assistance in finding where to change this. The zabbix setup was working perfectly on the previous installation and we are using the same hardware so it is not a resources issue.

I am hoping someone can assist with this.

[ecomchris]

Just an update, I was able to fix the issue. The issue had nothing to do with the Zabbix installation but was the arp cache size in Ubuntu that was full. I increased the arp cache size and zabbix is working as it was again.

[cyber]

Make sure that the fping binary has root ownership and the SUID flag set.

I think in earlier versions this was mentioned in installation notes also, but in current version of docs I found only reference to this from https://www.zabbix.com/documentation...#fpinglocation
I guess permissions can somhow obtained via capabilities also... Admins usually do not like setting suid bits, as there is probably a way to exploit it...:P

[ecomchris]

Just an update, I was able to fix the issue. The issue had nothing to do with the Zabbix installation but was the arp cache size in Ubuntu that was full. I increased the arp cache size and zabbix is working as it was again.