SNMP traps are visible in a packet capture on the WhatsUp Gold server but do not appear in WhatsUp Gold.

The following conditions may also be observed:

• The SNMP Trap Listener is enabled.
• UDP 162 traffic reaches the server.
• Packet checksums and packet integrity are valid.
• Passive monitor data is being written to the database.
• The passive monitor error log does not contain a related error.
• No SNMP trap activity is displayed for the sending device.

WhatsUp Gold may discard the trap without creating an error or log entry

SNMP traps are visible in a packet capture on the WhatsUp Gold server but do not appear in WhatsUp Gold.

The following conditions may also be observed:

• The SNMP Trap Listener is enabled.
• UDP 162 traffic reaches the server.
• Packet checksums and packet integrity are valid.
• Passive monitor data is being written to the database.
• The passive monitor error log does not contain a related error.
• No SNMP trap activity is displayed for the sending device.

WhatsUp Gold may discard the trap without creating an error or log entry.

WhatsUp Gold may silently discard an incoming SNMP trap when either of the following conditions is true:

• The trap source IP address does not match an interface assigned to a device in WhatsUp Gold, and Accept unsolicited SNMP traps is disabled.
• The device is known, but an enabled SNMP trap passive monitor is not assigned to the device or the correct device interface.

Additional causes can include:

• Another application or agent is also bound to UDP 162.
• The listener is bound to a specific local IP address instead of all server addresses.
• The sending device uses a loopback or management IP address that does not match an interface known to WhatsUp Gold.
• Windows Filtering Platform or another security driver drops the packet after it is recorded by packet-capture software but before it reaches the WhatsUp Gold process. 

Complete the following steps in order.

1. Verify the SNMP Trap Listener settings

On the WhatsUp Gold server:

1. Open Settings > Passive Monitor Listeners > SNMP Trap.
2. Confirm that the listener is enabled.
3. Confirm that the configured port matches the destination port used by the sending device.
4. Review the Accept unsolicited SNMP traps setting.

If unsolicited traps are not accepted, WhatsUp Gold must be able to match the trap source IP address to an interface belonging to a monitored device.

Important: Enable Accept unsolicited SNMP traps only for a limited testing period. Accepting traps from unmonitored sources may cause significant database growth.

2. Verify the trap source IP address

Use a packet capture to identify the source IP address contained in the incoming trap.

In WhatsUp Gold:

1. Open Discover > Device Properties for the sending device.
2. Confirm that the source IP address from the packet capture matches an interface assigned to that device.
3. Check whether the device sends traps from a loopback or management interface.
4. Add or correct the interface information if WhatsUp Gold does not recognize the source address.

The source IP must match exactly when unsolicited traps are not accepted. 

3. Verify the passive monitor assignment

In the device properties:

1. Open Passive Monitors.
2. Confirm that an SNMP trap passive monitor, such as Any Trap, is assigned.
3. Confirm that the monitor is enabled.
4. Confirm that the monitor is not marked as removed.
5. Verify that the monitor is associated with the interface that matches the trap source IP address. 

4. Confirm which process owns UDP 162

Open PowerShell as an administrator and run:

Review the output for the following:

• Multiple processes using UDP 162: Another application may receive the trap instead of WhatsUp Gold.
• LocalAddress other than 0.0.0.0: The listener may be bound to only one server address. Traps sent to another address may not reach the listener.

If another application owns UDP 162, stop or reconfigure that application so the WhatsUp Gold listener can receive the traps. 

5. Compare with a working WhatsUp Gold server

When another working WhatsUp Gold installation is available, compare:

• SNMP Trap Listener settings
• Accept unsolicited SNMP traps
• UDP 162 ownership and binding
• Device interface configuration
• Assigned passive monitors
• Recent SNMP trap activity

Configuration differences between the working and non-working installations can identify where the trap-processing pipeline is failing. 

6. Capture Windows packet-processing activity

If the listener, device, interface, and monitor configuration are correct, use pktmon to determine whether Windows passes the datagram to the WhatsUp Gold process.

Open Command Prompt as an administrator:

Allow traps to be sent for approximately five minutes, then run:

Review C:\Temp\traps.txt for components that handled or dropped the packet, including the Windows Filtering Platform. This helps determine whether the trap reached the WhatsUp Gold process or was dropped by Windows or a security component. 

Diagnostic Data to Collect

If the issue continues, collect the following:

• Packet capture showing incoming UDP 162 traffic
• SNMP Trap Listener configuration
• Output from Get-NetUDPEndpoint -LocalPort 162
• Device properties showing the source IP interface
• Assigned passive monitors for the sending device
• Comparison results from a working server, when available
• pktmon output from C:\Temp\traps.txt
• WUG Diagnostic Utility package

Important Notes

• A packet appearing in Wireshark confirms that it reached the network capture layer. It does not necessarily confirm that Windows delivered the packet to the WhatsUp Gold process.
• Do not reseed the passive monitor activity table solely because traps are missing. Confirm that the database activity log is not being written before considering database-level corrective action.
• Any SQL diagnostic queries used during troubleshooting should be read-only and should not include inserts, updates, deletes, database reseeds, or DBCC repair commands.