How to Get a Dynamic OID Suffix and Convert into SNMP Custom String Sensor

Hi Felix,

Thank you for the pointers. I managed to achieve what I wanted :)

I followed your advice.

I used NETSNMP to do the SNMP walk. I modified the script using this template https://kb.paessler.com/en/topic/73131 Credits goes to Dariusz Gorka :)

What the script does:

1. Does the snmpwalk of the OID of interest
2. Retrieves the number of instances (in my case, the number of alarms)
3. Outputs the string (in my case, the alarm description)

Since the script outputs the number of instances, I just enabled alerting based on limits, simply setting the upper error limit to 0. The moment that there is a device alarm, the sensor will go down :)

Also, since the script outputs the string, I am also able to see the alarm description on the 'Message' of PRTG. The message, however includes the OID and "STRING:" because of the output of the SNMP walk. I don't have any idea how to remove them and just retaining the string itself to make the message more neat. I tried several output options on the snmpwalk.exe command but I am not able to get it. Maybe others will have an idea on how to do this??? Here's a sample output of the string when I ran the PS script:

<text>Alarm Messages: .1.3.6.1.4.1.272.4.46.5.1.54 = STRING: "this is a test alarm"</text>

Below is the modified script. This is confirmed to be working based on my own tests.

Feedbacks are most welcome!

#    ____  ____  ____________
#   / __ \/ __ \/_  __/ ____/
#  / /_/ / /_/ / / / / / __  
# / ____/ _, _/ / / / /_/ /  
#/_/   /_/ |_| /_/  \____/                         
#    NETWORK MONITOR
#-------------------
#
# This script checks the current alarms of a target device with dynamic OID suffix using snmpwalk
#

# Parameter "-hostaddr" for the nCompass IP address
# Parameter "-community" for the SNMP v2c Community
# Parameter "-port" for the SNMP port of the device
# Parameter "-timeout" for the timeout of the request
# Parameter "-troubleshoot" for the troubleshooting of this script
param(
    [string]$hostaddr = "localhost",
    [string]$community = "public",
    [string]$port = "161",
    [string]$timeout = "5",
    [int]$troubleshoot = 0
)

$regex_string = "(STRING:..)([a-zA-Z0-9- ])"

[string[]] $walkresult = @(C:\usr\bin\snmpwalk.exe -Cc -Ln -On -v 2c -c $community $hostaddr":"$port ".1.3.6.1.4.1.272.4.46.5.1.54" -t $timeout 2>&1)

if ($troubleshoot -eq 1){
$walkresult_trouble = $walkresult -join ''
}

if (!($walkresult  -like "*= String: *")){
    $alarms = 0
} else {
    $alarms = $walkresult.count }


    [string]$walkresult_result = $walkresult -join ''


write-host "<prtg>"

write-host "<result>"
write-host "<channel>Number of Current Alarms</channel>"
write-host "<value>$($alarms)</value>"
write-host "</result>"

if($troubleshoot -eq 0){
    if (!($alarms -eq 0)){
        write-host "<text>Alarm Messages: $($walkresult_result)</text>"
    }
}

if ($troubleshoot -eq 1){
write-host "<text>$($walkresult_trouble)</text>"
}

write-host "</prtg>"