to monitor the universal forwarder use this query :
index=_internal source=*metrics.log group=tcpin_connections | eval Host=coalesce(hostname, sourcehost) | eval age = (now() - _time ) | stats min(age) as age, max(_time) as LastTime by Host | convert ctime(LastTime) as "Last Active On" | eval Status= case(age < 3600,"Running",age > 3600,"DOWN")|search Status=DOWN
This will show if any universal forwarder is down and will list out the host name and when it was connected last. (Will show if any forwarder is down for more then 1 hr)
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