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I am using Enterprise Unlimited Edition for monitoring my network devices. When I first installed PRTG, every thing went fine and I was performing my job very well.


One day I needed to format my Monitoring Server. After formatting, I reinstalled same PRTG Enterprise Unlimited Edition but this time none of the SNMP based sensors are working. I am running Server and probe on the same machine ( I also tried changing both of them on Interface IP but it did not work.

I have already checked my firewall for UDP ports, PRTGserver communication port and Probe port. All are open. I even checked by SNMPTester and that is working really fine that means there is no blockage for SNMP on the network. I also have another monitoring server with different tool(from different manufacturer) running in same VLAN. and that is working fine.

Whenever I try to add a custom SNMP sensor to it, it returns me "Error# 2003".

Please suggest some suitable trouble shooting so that I boost up my monitoring by adding PRTG.

Thanks and Warm Regards, Nutan.

custom-sensor snmp snmp-error#2003

Created on Oct 13, 2010 1:34:30 PM

8 Replies



If you scan against the OID you want to use with the custom sensor using the SNMP Tester does that work?

Created on Oct 13, 2010 3:30:17 PM by  Patrick Hutter [Paessler Support] (7,225) 3 3



Yes, that OID is working fine with SNMPTester. Moreover, its not actually for one particular OID, its with all SNMP Sensors(their respective OIDs).

FYI, I am using PRTG V7 with Enterprise Unlimited Edition.

My Opinion:

  1. Does it has something to do with SNMP Service and Trap destinations defined on Machine running PRTG.
  2. Can you please mail me the checklist(prerequisites) of configuring PRTG for SNMP monitoring?
  3. If I have Probe and Server running on same Machine, then are there any Port issues related to them?

Please take me as a beginner and ignore I am silly.

Warm Regards, Nutan

Created on Oct 14, 2010 4:25:24 AM

Last change on Oct 14, 2010 6:10:27 AM by  Daniel Zobel [Product Manager]



Are you wanting to monitor SNMP traps? In such a case you would need to use the SNMP Trap sensor, not the standard SNMP sensors. See: How can I use PRTG’s trap receiver and what are its limitations?

As to your queries:

  • 1. No. PRTG merely reads the value from the SNMP-compatible device. Of course the necessary information (including port, community string, etc.) need to be defined properly for the device in case.
  • 2. There are no prerequisites except that SNMP is configured and turned on at the device's end. If the SNMP Tester can access these values, so should PRTG.
  • 3. Not really.

Created on Oct 15, 2010 9:20:10 AM by  Patrick Hutter [Paessler Support] (7,225) 3 3



No, I dont want to monitor traps, It was just a question pinching my brain.

So, Enabling SNMP is not at all mandatory on the device running PRTG (Running both PRTG Core and Probe).

I tried Adding a SNMP trap reciever too....jst in case if it could work..but bingo...............It didn't...Silly I am.

I also tried it after restarting my PRTG Core Server Service and Probe service... but its not working.


In the post you have mentioned that Trap Sensor is to be added in local probe, but I found that No Sensors can be added to local probe from WebGUI however we can add sensors to probe device. If there is a way then plz suggest.

I also consider it safe to run probe on rather than on Ethernet Interface IP.


On first installation they all were working fine. I don't know what happened to them NOW........


Created on Oct 15, 2010 10:21:44 AM



Mr Patrick,

Good Afternoon..!!

No, I am not trying to monitor SNMP Traps. What I want is very much simple.

I have READ ONLY community strings of Network devices. I just want to use them for monitoring them as per Default profiles defined in PRTG (SNMP Based).

I am running both Probe and Server on same machine (Win XP SP2).

Probe Administrator Configuration: 1. Server Connection : Connect to loacl core server (via and port specified below : 23560)

2. Probe GID: {Some value}

3. Outgoing IP for monitoring requests: auto

Server Configuration:

1. Web Server : NIC (eth) 's IP (10.x.x.8) Port: 8080 2. Core Server : IPs for Probe connections: Localhost only (

No Firewall blockage or any kind of Community string issues. All is fine..


Please Help....... I beg....for Gods Sake..PLEASE HELP..

Created on Oct 18, 2010 12:00:37 PM



please open a support ticket we might have to do a remote session to take a look at this together

send mail to [email protected]

Created on Oct 26, 2010 6:53:04 PM by  Aurelio Lombardi [Paessler Support]

Last change on Oct 26, 2010 6:53:16 PM by  Aurelio Lombardi [Paessler Support]



Try to add UDP 161 and 162 to your firewall exceptions. works perfectly for me. Windows XP SP3 and 7

Created on Feb 7, 2013 12:23:27 PM



Please see also the article My SNMP sensor don't work. What can I do?

In general, the SNMP error #2003 often hints on problems with basic requirements such as access to ports, authentication, disabled SNMP, etc.

Created on Jan 21, 2014 4:49:45 PM by  Gerald Schoch [Paessler Support]

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.