How to check memory and incoming/outgoing connections of host. I have created memory usage i am getting error as below.
Name of service:Memory Usage Status:UNKNOWN Last Check:03-13-2020 04:05:45
Duration:0d 0h 17m 6s
Attempt:4/4
Status Info: Usage: check_memory [ -w ] [ -c ]
all of this row is in orange color on web interface.
In principle Nagios is a piece of software that is interested in "state", while you can collect metric data it's not what the software was originally written for. In order to determine the "state" of your memory, you need to tell the plugin what is and isn't an acceptable return value. This is normally done with warning and critical flags on the plugin itself (usually -w and -c).
Since the plugin has no idea what to do with the return value since no thresholds were specified, you get UNKNOWN.
Writing correct thresholds can be tricky so I suggest you look at example ranges to get an idea of what you should write.
