Re: Can Disman Event MIB monitor remote target's objects?

---------- Forwarded message ----------
From: ERICJ <[email protected]>
Date: Feb 12, 2008 4:42 PM
Subject: Re: Can Disman Event MIB monitor remote target's objects?
To: Dave Shield <[email protected]>


Thanks for your reply, Dave.

I still have some question not clearly understand,
Do you mean that  I misunderstanding the usage of
mteTriggertTargetTag?
and it's not used for store the remote target's info?
In my previous thoughts, I think that if I want to monitor a remote
target I have to query the value
from snmpTargetAddrTable with snmpTargetAddrTagList.
The mteTriggerTargetTag shoud refer to (pick up) an entry from
snmpTargetAddrTable.
And snmpTargetAddrEntry should store some information about the target
that I want to monitor such as IP and snmpv3 securityName.

Do I misunderstanding the usage of these objects?

On Jan 15, 2008 5:38 PM, Dave Shield <[email protected]> wrote:
>
> On 15/01/2008, ERICJ <[email protected]> wrote:
> > In DISMAN Event MIB's Trigger Table it defines
> >
> > mteTriggerTargetTag
> > The description says "The length of 0 indicates the local
> > system....Otherwise access rights are checked according to the security
> > parameters resulting from the tag"
> > Is this means I can use Target Tag to monitor different targets?
>
> In principle, yes.
>
>
> > And from the beginning of the RFC2981 Event MIB at the part of 3.
> > Relationship to Other MIBs. It indicates
> > "The key extension is the ability to allow alarms to be generated for MIB
> > objects that are on *another* network element"
> >
> > Is *another* network element means *remote* target?
>
> Yes.
>
>
> > i.e. I can set up entries in Target MIB with the remote monitored target's
> > IP address and infos
> > and set up mteTriggerTargetTag so that the agent can monitor remote agents
> > objects?
>
> Exactly.
>
>
>
> > I have tested the EVENT MIB with monitor local agent's objects,and it works
> > fine, but I am not sure whether net-snmp 5.4.1 have implemented the function
> > to monitor the other remote target's objects?
>
> I'm not entirely sure (as it's some time since I wrote this implementation),
> but I strongly suspect not.  I'm pretty sure that it currently only supports
> local queries.
>
> Checking the code, the processing of "monitor" directives (mteTriggerConf.c)
> sets up the session for retrieving MIB values using either
>    netsnmp_iquery_user_session("user");
> or
>    netsnmp_query_get_default_session();
>
> both of which assume a loopback connection to the local agent.
>
> Creating a monitor entry dynamically (i.e. via SET commands) uses
>    netsnmp_iquery_pdu_session( pdu )
> which uses the authentication settings of the incoming request,
> but again assumes a loopback connection to the local agent.
>
> I don't *think* that the TargetTag value is actually used anywhere.
> This is an obvious omission, and it would be sensible to addess this.
> If you were in a position to attempt this task, then what you'd basically
> need to do would be to adjust the creation of the "session" field in
> the event and trigger tables.   This is a standard netsnmp_session
> structure (as used in client commands, etc), and is used for retrieving
> the values to be monitored.
>   If this was set up to refer to a remote agent (rather the local loopback),
> then this *should* be sufficient to implement remote monitoring.

I have trace the struct of netsnmp_session in the snmp API,
It defines an peername to refer an remote target,
but if as I asked in the previous question, where should I store/
retrive the target's information
so that I could use to create a remote peer session?

>
> He says, not having actually done this, of course!
Do the implementation for DISMAN EVENT MIB to monitor remote object
will put into future works ?
I might have to implement the function, but I'm not familiar with C,
so I'm still surveying the document on the official website and
tracing the code.

If you can, could you give me some suggestion that which document or
code I should trace first?
Thank you in advance.
>
> Dave
>

--
It seems that if I reply from google groups the post can't be seen on
sourceforge's mailling list.
(but it's weired that I can read it from google groups and just no new
reply. Is the post from google groups will be filtered by
sourceforge's mailling list?)
So I repost my post again.
---
--
Guan-Hong Chen



-- 
Guan-Hong Chen

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