[SNMP4J] dual Agent/Manager v3 causing engineBoot and engineTime to be 0

[Frank Fock]

Hi Rushik,

You can use two (or more) separate USM instances. However, you need to be careful with that.
The following FAQ article describes the details:
http://oosnmp.net/confluence/pages/viewpage.action?pageId=1441800

For your proxy setup, you can easily use the 
http://www.snmp4j.org/agent/doc/org/snmp4j/agent/mo/snmp4j/MOSubtreeProxy.html
of SNMP4J-Agent.

Best regards,
Frank



> On 27 Feb 2016, at 20:59, <ru_44 at hotmail.com> <ru_44 at hotmail.com> wrote:
> 
> Figured out issue with security model overriding my usm.  
> Since security model is a singleton instance.  
> Is there a way to use different security model for multiple SNMP sessions?  
> I tried to set a new one by creating a new message processor and setting it in there.  
> 
> Sent from my iPhone
> 
>> On Feb 26, 2016, at 5:33 PM, ru_44 at hotmail.com wrote:
>> 
>> Hello,
>> I am working on a project using snmp4j where my application needs to be a dual agent/manager.  
>> Think of this as a relay, a middle man snmp application.
>> it will do the following:
>> 1)it will listen for requests from a  beginning SNMP client (mib browser for example).
>> 2) read those requests from beginning SNMP client, do some OID translation to my own custom MIB
>> 3) send the request with the OID translation to the end Client
>> 4) get the response from the end Client, do some backwards OID translation
>> 5) send the response PDU back to the beginning SNMP Client for the request from step 1
>> 
>> 
>> The way I developed this was for the agent end, I extended "BaseAgent" class in snmp4j agent for my agent to listen for requests from my beginning SNMP client.
>> I am overriding the processPdu method in "CommandProcessor" to intercept the requests in the "CommnadResponderEvent", do my OID translation.
>> For the manager end, then call a snmp Manager session within the "Command Processor" (using the "snmp" Class from snmp4j )to send the requests (get, getnext, getbulk) to my end Client
>> read the response back in "ResponseEvent" instance from the end Client.
>> parse the response and do my backwards OID translation and set the var bindings in the response PDU to be sent back to the Beginning Client using "returnResponsePDU" from the "commandResponderEvent"
>> 
>> 
>> my implementation is working for v1 and v2, but for v3 I am getting an issue with the response back to the Beginning Client in step 5 above.  the message Authoritative engineID and engineBoots are set to 0 which is causing the response to be discarded by the Beginning Client.  
>> I did some debugging and i know the engineID and engineBoots are set from the USM Time table based on the security state reference.
>> 
>> I am thinking my implementation is causing some conflict with the USM since my snmpManager is initialized and used within the Command Processor for the snmpAgent end. 
>> if i comment out my snmpManager, the response is sent back correctly with the engineID and engineBoots populated correctly from the USM. 
>> would it beneficial to maybe use the Proxy Forward feature in snmp4j instead of this approach?  I was thinking if using the Proxy Forward but i have to do some oid Translation so i needed to intercept the PDU so that is why i overloaded the processPDU function in the CommandProcessor class.
>> any help or insight would be appreciated.
>> 
>> thanks
>> Rushik
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
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