fping unreachable and host triggers down alert but ping is successful

[superlava]

Hi,

I've 2 hosts which are showing offline even while we're able ping from server and proxy. Upon troubleshooting found that while ping is successful, fping which is used by zabbix for send ICMP shows unreachable.

As per my understanding, Host should be reachable if we're able to ping and i couldn;t find any other reason for this issue.

Can you help if there's any difference between ping ang fping and how to resolve this.

[LenR]

Is it just 2 hosts, others work OK? Check the hosts primary interface in Zabbix? Is it set to use IP or DNS? Is the correct value specified there?

fping is an "add on" package used by Zabbix. Check that it is properly installed. You can test it from the command line. Verify that the zabbix user has rights to run fping.

[superlava]

Yes, It's just for 2 hosts only. We're able ping from proxy but not able ping using fping.

Any specific standard fping uses which should be allowed on CPE?

[markosa]

When you ping from server/proxy using fping from cli, is there any difference between failing and succesfull fping results? I've seen this behaviour previously, at a time it was related to fping version(output changed between different versions and zabbix was relaying to specific version), but I've seen that also when there's bonded interfaces and you get response from two different interface or something like that, can't remember that well anymore.
EDIT: never mind above one, you said there's no respose when using fping. Is there "smart" firewall between server/proxy and those one's which are failing? If so, do you see drops at fw logs?