I seem to recall having done this long ago, but now it seems different.
I setup an snmp poll for some variables, through a fire walled host. I use port 21161 and forward to 161 internally, and pull my values. However the host check fails because the firewall doesn't forward that, or respond to pings.
In the past, I changed that check to use an snap variable "sysUptimeInstance" and that worked. I have long ago deleted that configuration. Setting up today, however, fails because the check I used log ago now seems to automatically place "161" as the port number instead of my custom 21161.
CMD: /usr/bin/snmpget -t 1 -r 5 -m DISMAN-EVENT-MIB -v 1 [authpriv] xx.xx.xx.xx:161 sysUpTimeInstance
I don't know where that is coming from. I tried to append 21161 onto the IP, and the check fails like this:
CMD: /usr/bin/snmpget -t 1 -r 5 -m DISMAN-EVENT-MIB -v 1 [authpriv] xx.xx.xx.xx