Troubleshooting SNMP scanning issues

SNMP is one of the protocols through which Lansweeper can retrieve data regarding network devices like printers, switches, routers etc. By default, Lansweeper retrieves various properties from these devices via SNMP. This includes basic details such as serial number and description, but also more advanced details such as interface and toner information. This article explains how to troubleshoot SNMP scanning issues.

If the SNMP protocol was not scanned for a device in your network, do the following:

  1. Follow the steps in this article to ensure there is no general scanning issue.
  2. Make sure that TCP port 135 is closed on the device, as having this port open will cause the device to be identified as a Windows computer. Windows computers are not scanned via SNMP.
  3. Make sure SNMP is enabled on the device.
    The procedure to enable SNMP can vary greatly between devices. Consult your vendor's documentation.
  4. Make sure SNMP on the device responds to a read request on OID 1.3.6.1.2.1.1.2.0. This is a system OID that should exist on SNMP enabled devices. Lansweeper tries to read this OID first. If no response is given, it is assumed SNMP is disabled or not working and Lansweeper skips SNMP scanning.
  5. Make sure SNMP traffic in your network (over port 161) isn't blocked. Scanning requests are sent outbound by your Lansweeper server and are accepted inbound on your network devices.
  6. If you're using an SNMPv3 credential, make sure FIPS compliance is not enabled on your Lansweeper server.
  7. Use the devicetester.exe tool, found in the folder below on your Lansweeper server, to test the SNMP connection to the device. Launch the tester from your Lansweeper server directly, submit the IP address of the device and your SNMP credential. Read-only rights are sufficient for your credential. A successful SNMP test should list the ObjectID of the device as seen in the screenshot below.
    Program Files (x86)\Lansweeper\Actions
    using devicetester to test SNMP access
  8. Once SNMP access works in the test tool, make sure the correct SNMP community string with read access (the one previously used in devicetester) is submitted under Scanning\Scanning Credentials in Lansweeper and mapped to the device.
  9. Rescan the network device, e.g. by hitting the Rescan Asset button on the device's Lansweeper webpage.
  10. Verify whether SNMP was scanned by looking for an OID in the Summary tab of the device's webpage. If no OID is present here, SNMP wasn't scanned and custom OIDs cannot be scanned either.
    device OID on asset page

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