I've added a custom sensor to my device. The sensor on PRTG constantly only shows "No Response (Error #2003)".

I downloaded and ran the 'SNMP Tester' tool with identical errors. A copy of the log is below:

----------------------- New Test -----------------------
Paessler SNMP Tester 5.2.3 Computername: HP-HP Interface: (192.168.1.117)
8/2/2017 11:30:16 AM (2 ms) : Device: 192.168.1.137
8/2/2017 11:30:16 AM (3 ms) : SNMP V2c
8/2/2017 11:30:16 AM (5 ms) : Custom OID 1.3.6.1.4.1.22154.3.1.2.5.1.2.6.0
8/2/2017 11:30:18 AM (2012 ms) : SNMP Datatype: ASN_PRIMITIVE
8/2/2017 11:30:18 AM (2014 ms) : -------
8/2/2017 11:30:18 AM (2016 ms) : Value: No response (check: firewalls, routing, snmp settings of device, IPs, SNMP version, community, passwords etc) (SNMP error # -2003)
8/2/2017 11:30:18 AM (2018 ms) : Done

However, during this same test I kept Wireshark running to monitor what was actually being sent. Looking at the packets sent there, it shows a valid request and valid response, with the expected value from my sensor being sent. Wireshark was running on the same machine as SNMP Tester, meaning there's no possibility of differences in firewalls, ip conflicts, routing, etc.

A copy of the packet log of the response is below:

No.     Time           Source                Destination           Protocol Length Info
    180 3.315765       192.168.1.137         192.168.1.117         SNMP     93     get-response 1.3.6.1.4.1.22154.3.1.2.5.1.2.6.0

Frame 180: 93 bytes on wire (744 bits), 93 bytes captured (744 bits) on interface 0
Internet Protocol Version 4, Src: 192.168.1.137, Dst: 192.168.1.117
User Datagram Protocol, Src Port: 161, Dst Port: 58800
    Source Port: 161
    Destination Port: 58800
    Length: 59
    Checksum: 0xa9fe [unverified]
    [Checksum Status: Unverified]
    [Stream index: 22]
Simple Network Management Protocol
    version: version-1 (0)
    community: public
    data: get-response (2)
        get-response
            request-id: 1300
            error-status: noError (0)
            error-index: 0
            variable-bindings: 1 item
                1.3.6.1.4.1.22154.3.1.2.5.1.2.6.0: 27473
                    Object Name: 1.3.6.1.4.1.22154.3.1.2.5.1.2.6.0 (iso.3.6.1.4.1.22154.3.1.2.5.1.2.6.0)
                    Value (Integer32): 27473

"27473" is the correct expected value to be returned. The time delay between request/response is 0.005 seconds, so the PRTG certainly did not time-out.

What could be causing PRTG to not recognize this response?

Article Comments

Hello derekm,
thank you your KB Post.

This looks very interesting. Your SNMP Tester log reads:

8/2/2017 11:30:16 AM (2 ms) : Device: 192.168.1.137
8/2/2017 11:30:16 AM (3 ms) : SNMP V2c

But the output from wireshark states that the reply was sent with SNMP V1:

No.     Time           Source                Destination           Protocol Length Info
    180 3.315765       192.168.1.137         192.168.1.117         SNMP     93     get-response 1.3.6.1.4.1.22154.3.1.2.5.1.2.6.0

Simple Network Management Protocol
    version: version-1 (0)
    community: public

If the query was sent in v2c, the device should reply in v2c. Set the SNMP Version to V1 in the Tester (and PRTG) and let me know how it works afterwards. :)

Best Regards,
Luciano Lingnau [Paessler Support]


Aug, 2017 - Permalink

Hi Luciano,

You are correct, setting the device to SNMPv1 on PRTG worked.

I thought I had seen on this device that it supported v2c. It is interesting that when receiving a v2c request it replies with v1.

Thanks for the support.


Aug, 2017 - Permalink