Re: Connect 1 agent/application to several snmpd/master

Hi all,

adding some clarifications on the proposed design I would like to propose:

The use case should cover two cases.
Each case is exclusive of the other.
a- stick one MIB to one connection. use case with multiple connections.
b- stick several MIB in one connection. use case with single connection.

The following is proposed:
- extend agentx subagent code to multiple sessions
a linked list of config sessions is created indexed by agentxsocket path

the sub agent code is modified accordingly.
at registration/unregistration of the session, a reference is done between
netsnmp_session and config_netsnmp_session.
at shutdown, the config session can be flushed based on the agentxsocket
path too.

example of config file:
agentxsocket unix:/var/run/netns/test/agentx_snmpd
[..]
agentxsocket unix:/var/run/netns/test2/agentx_snmpd

- add a linked list to the config sessions. that contains the list of mib
contexts names.
example of config file that could be applied for a) case:
agentxsocket unix:/var/run/netns/test/agentx_snmpd    name1

example of config file that could be applied for b) case:
agentxsocket unix:/var/run/netns/test/agentx_snmpd    name1,name2,name3

The advantage of using the config session list, is that there is no need to
modify netsnmp_session.
MIB (un)registration would be filtered by comparing the MIB registration
name with the list of MIB names configured.

The same would be done to check if a trap is eligible or not to a
netsnmp_session or not.

Thanks for letting me know if that approach should be considered or not,
Thanks & Regards,
Philippe



On Fri, Nov 6, 2020 at 11:52 AM Philippe Guibert <[email protected]>
wrote:

> Hi all,
>
> I am in progress of implementing more than one parent agent for one agentX.
> The problem I try to solve is that I have multiple MIB with same OID but
> different vrfs.
>
> Do you have any proposals on how to stick MIBs to one dedicated parent
> connection ?
> From the sub agent trap code, I can see that a trap is supposed to be sent
> to all pending connections, but I think this is not what should be done by
> default ?
> Thanks,
>
> Regards,
> Philippe
>
>
> On Tue, Oct 13, 2020 at 5:49 PM Wes Hardaker <
> [email protected]> wrote:
>
>> Philippe Guibert <[email protected]> writes:
>>
>> > Instead of using agentX, I wonder if it could be possible to link the
>> > application with a master agent library Somehow, the agent would be
>> > configured as a proxy, and session would convey information over an
>> > unixSocket to the real snmpAgent.  Could it be possible ?
>>
>> Yes, certainly you can have multiple "real" snmp daemons query to a
>> sub-process via a proxy like mechanism.  There is no reason that
>> shouldn't work to allow multiple upstreams query to your internal agent.
>>
>> The net-snmp package's snmpd actually supports that through the use of
>> the "proxy" directive ; see the snmpd.conf manual page in the "Proxy
>> Support" section.
>>
>> --
>> Wes Hardaker
>> Please mail all replies to [email protected]
>>
>

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