A complete step-by-step guide on integrating Didactum monitoring devices and sensors into GroundWork Monitor via SNMP - including host profiles, command configuration, service checks for all sensor types, SNMP trap integration via SNMPTT, and email alerting.

Architectural Note: 

GroundWork Monitor utilizes Nagios as its polling and notification engine, as well as Nagios plugins to execute service checks. For SNMP queries, Nagios invokes a local SNMP client and passes the host address and OID. Configuration can be performed either via the graphical Monarch web interface or directly through Nagios configuration files.

• Software: GroundWork Monitor (Open Source or Enterprise Edition)
• Engine: Nagios + Monarch (Web Configuration Tool)
• SNMP Traps: SNMPTT (SNMP Trap Translator)
• Protocol: SNMP v1 / v2c / v3
• Devices: Didactum Monitoring System 100 / 500T / 500 II
• Sensors: Temperature, Leakage, Humidity, Door Contact, Smoke

GroundWork Monitor Server

• GroundWork Monitor installed (Open Source or Enterprise)
• Web interface (Monarch) accessible: <Server-IP>/monarch
• Status console accessible: <Server-IP>/gwos
• UDP port 161 open outbound for SNMP polling
• UDP port 162 open inbound for SNMP traps (Enterprise Edition)
• Network access to the Didactum device

Didactum Device

• Monitoring System 100T, 300T, 500T or 550T
• SNMP enabled (v2c recommended)
• Device reachable via ICMP from the GroundWork server
• MIB file available in the web interface

Architecture & Data Flow

[GroundWork Monitor Server]         [Didactum Monitoring System]
  IP: 192.168.1.10                    IP: 192.168.1.50
  /usr/groundwork/
  Monarch (Web Config)
  Nagios (Polling Engine)
  SNMPTT (Trap Handler)
                     --check_snmp UDP/161-->
                     <--SNMP Traps UDP/162--

Important GroundWork Paths

/usr/groundwork/nagios/etc/         <-- Nagios configuration
/usr/groundwork/nagios/etc/objects/ <-- Hosts, services, commands
/usr/groundwork/etc/snmptt/         <-- SNMPTT configuration
/usr/share/snmp/mibs/               <-- MIB files
/usr/groundwork/nagios/plugins/     <-- Nagios plugins (check_snmp)

Step 1 – Open Web Interface

Open in browser: 192.168.1.50 (adjust IP of the Didactum device)

Step 2 – Open SNMP Settings

System Settings → SNMP

Step 3 – Enter the Following Values

SNMPv3 Settings (optional)

# Install SNMP tools and plugins
sudo apt update
sudo apt install -y snmp snmp-mibs-downloader \
    nagios-plugins monitoring-plugins

# Test check_snmp plugin
/usr/lib/nagios/plugins/check_snmp --help | head -5

# Alternative: GroundWork-specific plugin path
ls /usr/groundwork/nagios/plugins/check_snmp

Test SNMP connection to the Didactum device in advance:

# List all sensor values
snmpwalk -v 2c -c didactum_groundwork 192.168.1.50 \
    .1.3.6.1.4.1.46501.5.1.1

# Temperature value (raw value ÷ 10 = degrees Celsius)
snmpget -v 2c -c didactum_groundwork 192.168.1.50 \
    .1.3.6.1.4.1.46501.5.1.1.7.101001

Step 1 – Download MIB from the Didactum Web Interface

System Settings → SNMP → "Download MIB file" → didactum.mib

Step 2 – Install MIB on the GroundWork Server

sudo cp didactum.mib /usr/share/snmp/mibs/
echo "mibdirs /usr/share/snmp/mibs" | sudo tee -a /etc/snmp/snmp.conf
echo "mibs ALL" | sudo tee -a /etc/snmp/snmp.conf

# Test using MIB name
snmpwalk -v 2c -c didactum_groundwork -m ALL 192.168.1.50 \
    DIDACTUM-MIB::sensorValue

Step 3 – Provide MIB for SNMPTT (Trap Reception)

sudo cp didactum.mib /usr/groundwork/etc/snmptt/mibs/
# or:
sudo cp didactum.mib /usr/share/snmp/mibs/

Option A – Via the Monarch Web Interface

Monarch → Configuration → Commands → Add Command

Command: Didactum Temperature

Command: Didactum Leakage

Command: Didactum Sensor Status

Command: Didactum Humidity

Option B – Directly as a Nagios Configuration File

sudo nano /usr/groundwork/nagios/etc/objects/didactum-commands.cfg

# ================================================================
# Didactum SNMP Check Commands
# File: /usr/groundwork/nagios/etc/objects/didactum-commands.cfg
# ================================================================
# ARG1=Community, ARG2=OID, ARG3=Warning, ARG4=Critical
define command {
    command_name    check_didactum_temperature
    command_line    $USER1$/check_snmp -H $HOSTADDRESS$ \
                    -C $ARG1$ -P 2 -o $ARG2$ \
                    -w $ARG3$ -c $ARG4$ \
                    -l "Temperature" -u "0.1Degree"
}
# ARG1=Community, ARG2=OID
define command {
    command_name    check_didactum_leakage
    command_line    $USER1$/check_snmp -H $HOSTADDRESS$ \
                    -C $ARG1$ -P 2 -o $ARG2$ \
                    -w 0:0 -c 1:1 -l "Leakage"
}
# ARG1=Community, ARG2=OID, ARG3=Label
define command {
    command_name    check_didactum_status
    command_line    $USER1$/check_snmp -H $HOSTADDRESS$ \
                    -C $ARG1$ -P 2 -o $ARG2$ \
                    -w 0:0 -c 1:2 -l "$ARG3$"
}
# ARG1=Community, ARG2=OID, ARG3=Warning, ARG4=Critical
define command {
    command_name    check_didactum_humidity
    command_line    $USER1$/check_snmp -H $HOSTADDRESS$ \
                    -C $ARG1$ -P 2 -o $ARG2$ \
                    -w $ARG3$ -c $ARG4$ \
                    -l "Humidity" -u "%"
}
# ARG1=Community, ARG2=OID
define command {
    command_name    check_didactum_door
    command_line    $USER1$/check_snmp -H $HOSTADDRESS$ \
                    -C $ARG1$ -P 2 -o $ARG2$ \
                    -w 1:1 -l "Door contact"
}

Host profiles in Monarch bundle host templates and service profiles for reuse across multiple devices.

Step 1 – Create Host Template

Monarch → Configuration → Host Templates → Add Template

Step 2 – Create Service Profile for Didactum

Monarch → Configuration → Service Profiles → Add Profile
  Profile Name: Didactum Sensors
  Description: SNMP service checks for Didactum monitoring system

Assign all Didactum services to this profile (after creating the services in section 8).

Step 3 – Create Host Profile

Monarch → Configuration → Host Profiles → Add Profile
  Profile Name:     Didactum Monitoring System
  Host Template:    didactum-monitoring-template
  Service Profile:  Didactum Sensors

Option A – Via the Monarch Web Interface

Monarch → Configuration → Hosts → Add Host

Click Save.

Option B – As a Nagios Configuration File

sudo nano /usr/groundwork/nagios/etc/objects/didactum-hosts.cfg

# ================================================================
# Didactum Host Configuration
# File: /usr/groundwork/nagios/etc/objects/didactum-hosts.cfg
# ================================================================
define host {
    use                     didactum-monitoring-template
    host_name               didactum-monitor-01
    alias                   Didactum Monitoring System 01
    address                 192.168.1.50
    contact_groups          admins
    hostgroups              didactum-monitoring
}
define hostgroup {
    hostgroup_name  didactum-monitoring
    alias           Didactum Monitoring Devices
    members         didactum-monitor-01
}

Option A – Via the Monarch Web Interface

Monarch → Configuration → Services → Add Service

Service: Temperature Sensor

Service: Leakage Sensor

Service: Temperature Sensor Status

Service: Humidity

Service: Door Contact

Option B – All Services as a Nagios Configuration File

sudo nano /usr/groundwork/nagios/etc/objects/didactum-services.cfg

# ================================================================
# Didactum Service Configuration
# File: /usr/groundwork/nagios/etc/objects/didactum-services.cfg
# IMPORTANT: Temperature thresholds are raw values × 10
#            28°C = 280, 35°C = 350
# ================================================================
define servicegroup {
    servicegroup_name   Didactum-Sensors
    alias               Didactum Sensor Services
}
# --- Temperature measurement ---
define service {
    use                     generic-service
    host_name               didactum-monitor-01
    service_description     Didactum-Temperature-Sensor-01
    check_command           check_didactum_temperature!didactum_groundwork!.1.3.6.1.4.1.46501.5.1.1.7.101001!280!350
    check_interval          5
    retry_interval          1
    max_check_attempts      3
    notification_interval   60
    notification_options    w,c,r
    contact_groups          admins
    servicegroups           Didactum-Sensors
}
# --- Temperature status ---
define service {
    use                     generic-service
    host_name               didactum-monitor-01
    service_description     Didactum-Temp-Status-Sensor-01
    check_command           check_didactum_status!didactum_groundwork!.1.3.6.1.4.1.46501.5.1.1.6.101001!Temp-Status
    check_interval          5
    retry_interval          1
    max_check_attempts      3
    notification_options    c,r
    contact_groups          admins
    servicegroups           Didactum-Sensors
}
# --- Leakage sensor ---
define service {
    use                     generic-service
    host_name               didactum-monitor-01
    service_description     Didactum-Leakage-Sensor-01
    check_command           check_didactum_leakage!didactum_groundwork!.1.3.6.1.4.1.46501.5.1.1.7.107001
    check_interval          2
    retry_interval          1
    max_check_attempts      1
    notification_interval   30
    notification_options    c,r
    contact_groups          admins
    servicegroups           Didactum-Sensors
}
# --- Humidity ---
define service {
    use                     generic-service
    host_name               didactum-monitor-01
    service_description     Didactum-Humidity-Sensor-01
    check_command           check_didactum_humidity!didactum_groundwork!.1.3.6.1.4.1.46501.5.1.1.7.102001!80!90
    check_interval          5
    retry_interval          1
    max_check_attempts      3
    notification_options    w,c,r
    contact_groups          admins
    servicegroups           Didactum-Sensors
}
# --- Door contact ---
define service {
    use                     generic-service
    host_name               didactum-monitor-01
    service_description     Didactum-DoorContact-01
    check_command           check_didactum_door!didactum_groundwork!.1.3.6.1.4.1.46501.5.1.1.7.104001
    check_interval          1
    retry_interval          1
    max_check_attempts      1
    notification_interval   30
    notification_options    w,r
    contact_groups          admins
    servicegroups           Didactum-Sensors
}
# --- Smoke detector ---
define service {
    use                     generic-service
    host_name               didactum-monitor-01
    service_description     Didactum-Smoke-Detector-01
    check_command           check_didactum_leakage!didactum_groundwork!.1.3.6.1.4.1.46501.5.1.1.7.106001
    check_interval          1
    retry_interval          1
    max_check_attempts      1
    notification_interval   30
    notification_options    c,r
    contact_groups          admins
    servicegroups           Didactum-Sensors
}

Include configuration in nagios.cfg

sudo nano /usr/groundwork/nagios/etc/nagios.cfg

Add the following lines:

cfg_file=/usr/groundwork/nagios/etc/objects/didactum-commands.cfg
cfg_file=/usr/groundwork/nagios/etc/objects/didactum-hosts.cfg
cfg_file=/usr/groundwork/nagios/etc/objects/didactum-services.cfg

SNMPTT (SNMP Trap Translator) is an SNMP trap handler written in Perl for use with the Net-SNMP snmptrapd program. SNMPTT supports Linux, UNIX, and Windows and can send traps to text logs, syslog, NT event log, or an SQL database, as well as call external programs to forward translated traps to email clients or Nagios.

Step 1 – Install SNMPTT

sudo apt install snmptrapd snmptt -y

Step 2 – Configure snmptrapd

sudo nano /etc/snmp/snmptrapd.conf

# Community string for trap reception
authCommunity execute,log,net didactum_groundwork
# Forward all traps to SNMPTT
traphandle default /usr/sbin/snmptthandler

Step 3 – Create SNMPTT Configuration for Didactum

sudo nano /usr/groundwork/etc/snmptt/snmptt.conf

Insert the following block:

# ================================================================
# Didactum SNMP Trap Definitions for SNMPTT
# ================================================================

# Leakage trap: water detected
EVENT didactumLeakAlarm .1.3.6.1.4.1.46501.5.1.1.7.107001 "Status Events" Critical
FORMAT DIDACTUM LEAKAGE ALARM: Water detected – Sensor $2 – Value: $4
EXEC /usr/groundwork/nagios/etc/snmptt-to-nagios.sh "didactum-monitor-01" "Didactum-Leakage-Sensor-01" "2" "CRITICAL: Leakage detected – Value: $4"
SDESC
Didactum water sensor has detected water (value = 1)
EDESC

# Temperature alarm trap
EVENT didactumTempAlarm .1.3.6.1.4.1.46501.5.1.1.6.101001 "Status Events" Critical
FORMAT DIDACTUM TEMPERATURE ALARM: Sensor $2 – Status: $4
EXEC /usr/groundwork/nagios/etc/snmptt-to-nagios.sh "didactum-monitor-01" "Didactum-Temp-Status-Sensor-01" "2" "CRITICAL: Temperature alarm – Status: $4"
SDESC
Didactum temperature sensor reports alarm condition
EDESC

# Smoke detector trap
EVENT didactumSmokeAlarm .1.3.6.1.4.1.46501.5.1.1.7.106001 "Status Events" Critical
FORMAT DIDACTUM SMOKE DETECTOR ALARM: Smoke detected – Sensor $2
EXEC /usr/groundwork/nagios/etc/snmptt-to-nagios.sh "didactum-monitor-01" "Didactum-Smoke-Detector-01" "2" "CRITICAL: Smoke detected!"
SDESC
Didactum smoke detector has detected smoke
EDESC

# Door alarm trap
EVENT didactumDoorAlarm .1.3.6.1.4.1.46501.5.1.1.7.104001 "Status Events" Warning
FORMAT DIDACTUM DOOR ALARM: Door opened – Sensor $2
EXEC /usr/groundwork/nagios/etc/snmptt-to-nagios.sh "didactum-monitor-01" "Didactum-DoorContact-01" "1" "WARNING: Door opened"
SDESC
Didactum door contact reports opened door
EDESC

Step 4 – Create Nagios Passive Check Script

sudo nano /usr/groundwork/nagios/etc/snmptt-to-nagios.sh

#!/bin/bash
# ================================================================
# SNMPTT → Nagios Passive Check Forwarding
# Arguments: $1=Hostname, $2=Service, $3=Status(0-3), $4=Message
# ================================================================
NAGIOS_CMD="/usr/groundwork/nagios/var/rw/nagios.cmd"
HOST="$1"
SERVICE="$2"
STATUS="$3"
MESSAGE="$4"
TIMESTAMP=$(date +%s)
if [ -p "$NAGIOS_CMD" ]; then
    echo "[$TIMESTAMP] PROCESS_SERVICE_CHECK_RESULT;$HOST;$SERVICE;$STATUS;$MESSAGE" \
        >> "$NAGIOS_CMD"
fi

sudo chmod +x /usr/groundwork/nagios/etc/snmptt-to-nagios.sh

Step 5 – Create Passive Services for Trap Reception

Add the following to the configuration file (passive reception without active polling):

define service {
    host_name               didactum-monitor-01
    service_description     Didactum-SNMP-Trap-Receiver
    check_command           check_dummy!0!"Waiting for SNMP traps"
    active_checks_enabled   0
    passive_checks_enabled  1
    max_check_attempts      1
    check_interval          10
    check_period            24x7
    notification_interval   30
    notification_period     24x7
    notification_options    c,r
    contact_groups          admins
}

Step 6 – Start Services

sudo systemctl enable snmptrapd snmptt
sudo systemctl start snmptrapd snmptt

All Didactum OIDs begin with .1.3.6.1.4.1.46501 (older firmware) or .1.3.6.1.4.1.39052 (newer models). The sensor ID is appended at the end.

OID Fields per Sensor

Sensor Types with OIDs and Thresholds

Determine sensor ID:

In the Didactum web interface under System tree → select sensor → Details. This ID is appended to the end of the OID.

Temperature thresholds:

The Didactum device provides temperature values as raw value × 10. 28.0 °C = OID value 280. Therefore, all check_snmp thresholds must also be specified × 10.

MIB prefix per model:

Older devices use .1.3.6.1.4.1.46501, newer ones may use .1.3.6.1.4.1.39052. Refer to the MIB file of your device for the exact OIDs.

Step 1 – Create Contact

Monarch → Configuration → Contacts → Add Contact

Step 2 – Create Contact Group

Monarch → Configuration → Contact Groups → Add Group
  Group Name: admins
  Alias: Administrators
  Members: admin

Step 3 – Ensure Email Sending

sudo apt install postfix mailutils -y
echo "Test GroundWork" | mail -s "Test" admin@yourdomain.com

Step 4 – Verify GroundWork Notification Commands

# Show existing notification commands:
grep -A5 "notify-service-by-email" \
    /usr/groundwork/nagios/etc/objects/commands.cfg

Validate Nagios Configuration

# Check configuration
sudo /usr/groundwork/nagios/bin/nagios -v \
    /usr/groundwork/nagios/etc/nagios.cfg

# Expected output: "Things look okay - No serious problems..."

# Reload Nagios
sudo /usr/groundwork/bin/gwservices restart nagios
# or:
sudo systemctl reload nagios

Test check_snmp directly

# Temperature value (raw value ÷ 10 = degrees Celsius)
/usr/lib/nagios/plugins/check_snmp \
    -H 192.168.1.50 -C didactum_groundwork -P 2 \
    -o .1.3.6.1.4.1.46501.5.1.1.7.101001 \
    -w 280 -c 350 -l "Temperature"
# Expected output: SNMP OK - 235

# Leakage status
/usr/lib/nagios/plugins/check_snmp \
    -H 192.168.1.50 -C didactum_groundwork -P 2 \
    -o .1.3.6.1.4.1.46501.5.1.1.7.107001 \
    -w 0:0 -c 1:1 -l "Leakage"
# Expected output when sensor is dry: SNMP OK - 0

Check Service Status in GroundWork

GroundWork status console: 192.168.1.10/gwos
→ Services → Filter: Host = didactum-monitor-01
→ Display status of all Didactum services

Error Messages and Solutions

Didactum Device

• SNMP enabled (v2c or v3)
• Community string set (not “public”): didactum_groundwork
• Trap receiver IP set to GroundWork server
• Trap port 162 configured
• MIB file downloaded
• snmpwalk test from the GroundWork server successful

GroundWork Server – Packages & MIB

• Packages snmp, snmp-mibs-downloader, nagios-plugins installed
• MIB file stored under /usr/share/snmp/mibs/
• check_snmp plugin available and functional
• UDP 161 outbound, UDP 162 inbound open

Monarch / Nagios Configuration

• check_snmp commands defined for all sensor types
• Host template and host profile for Didactum created
• Host didactum-monitor-01 added
• Services created for temperature, leakage, humidity, door contact, smoke detector
• Temperature thresholds entered × 10 (28°C = 280)
• Configuration validated with nagios -v (no errors)
• Monarch: Commit and Deploy executed
• Status console: All services visible and green

SNMP Traps (Enterprise Edition)

• snmptrapd and snmptt installed and configured
• snmptt.conf: Didactum trap definitions added
• Nagios passive check script created and executable
• Passive service for trap reception created
• Test trap received and visible in Nagios

Notification

• Postfix / mail delivery working (test email received)
• Contact with email address created
• Contact group admins assigned to host/service
• Test alarm triggered and email received