205 Device IP not reachable SNMP++: SNMP request timed out, increasing timeout settings does not resolve it, SNMP port is closed

Last Modified

Mon Nov 27 11:11 GMT 2023

Description

  • A monitoring status, monitored by a probe via SNMP, produces the following error message:
    • Error: 205 Device IP not reachable SNMP++: SNMP request timed out
  • Increasing the timeout settings under Settings > Monitoring Options > SNMP Settings does not resolve the issue.
  • Attempting to Telnet to the device from the probe via the defined SNMP port, set under Settings > Monitoring Options > SNMP Settings, returns the following error message:
    • Could not open connection to the host, on port 161: Connect failed
  • This error message indicates that the port used to monitor the device is closed.

Environment

  • N-able N-central

Solution

  • Verify the port status. Because SNMP utilizes UDP, this is a stateless connection which does not report success or fail.

  • We must send the endpoint a direct query using an SNMP / MIB walking tool ensuring that the following are correct :

    • IP and UDP Port (usually 161 the default SNMP port)

    • Community String (defaults to “public” in most cases)

    • Starting OID for our walk (Usually .1.3.6 is best)

    • Credentials (Only Applicable to SNMPv3)

  • If our Walk returns any information, we have an open port. If no data is returned, or we receive a timeout message, then the port is not accessible for some reason.

  • To resolve this please do either of the following options:
    • Open the port found under Settings > Monitoring Options > SNMP Settings locally and check its settings. We also recommend verify that there is no web monitoring software blocking access to the specified port.

    • Change the port number to the one used by SNMP under Settings > Monitoring Options > SNMP Settings

  • Run netstat -an at the Command Prompt to view the list of listening ports on the computer.