Re: Can the proxy agent work with internal query?

On Tue, Feb 12, 2008 at 6:36 PM, Dave Shield <[email protected]> wrote:
> On 12/02/2008, ericj <[email protected]> wrote:
>  > I had set up a proxy agent with net-snmp 5.4.1 on linux,and I have a
>  > switch with snmpv3 agent.
>  >
>  > I can run
>  >   "snmpwalk -v 3 -u testuser -A 12345678 -l authNoPriv 10.10.32.4 system"
>  > and have return values so that I'm sure the snmpv3 configuration on
>  > switch is okay.
>
>  Those are the settings for querying the remote switch.
>
>
>
>
>  > I want the queries via proxy agent, and I added follow lines in
>  > snmpd.conf
>  >
>  > proxy -Cn ctx_remotehost2
>
>  which sets up proxing for requests received using this context
>
>
>  >     -v 3 -u testuser -a MD5 -A "12345678" -l authNoPriv 10.10.32.4
>
>  and forwards such requests using these credentials
>  (which you've confirmed work).
>
>  OK so far.
>
>
>  But note that this proxying has been set up for incoming requests
>  in the context "ctx_remotehost2"
>
>
>
>  > but it seems that I still have to add in snmpd.conf
>  >
>  > com2sec -Cn ctx_remotehost2 proxied default cmty_2
>
>  Which is what this line does.
>  It maps the community "cmty_2" into the (internal) context
>  "ctx_remotehost2".   That means the agent recognises it
>  as relating to the "proxy" directive (which specified the same
>  context) and passes the request on to the switch.
>
>  Without this com2sec line, the agent would treat the
>  incoming request as being in the default context, and
>  attempt to process the requested varbinds itself.
>
>
>  Note that if you were using SNMPv3 for the incoming
>  requests, then you could specify the context explicitly.
>  But SNMPv1/2c pre-date the idea of contexts, so this
>  mapping needs to be done within the agent.
>
>
>
>
>  > Since the net-snmp had implement the disman event MIB with internal
>  > query,
>  > I was wondering that how if I setup a proxy agent, and could disman
>  > could monitor the proxy agent's MIB objects?
>
>  That *might* work.
>  I'm just concerned that bug #1689163 might be relevant here.
>  But you can but try.

Thanks Dave.
Actually what I want to do is as the same as the bug request ID
1058412 "Disman Monitoring over Net-SNMP Proxy fails"
since I had proxy a switch agent via net-snmp and can query switch
agent's MIB objects by command line
, but in snmpd.conf I can't specisify a context name to monitor the
proxied agent.

ex:
configure a proxyed agent.
proxy -Cn ctx_remotehost2 -v 3 -u testuser -a MD5 -A "12345678" -l
authNoPriv 10.10.32.4

How if it possibile that let net-snmp support specify a context in the
monitor configuration line such as
monitor -Cn ctx_remotehost2 -D -r 10 "Network Traffic" ifInOctets.1
1000000 5000000
so that net-snmp can monitor a specisified proxied agent?

It's very kind of your help. Thanks for your answer.
It really helps!

>
>
>
>  > As far as I know, if the proxy agent can only queried via v1/v2c
>  > community,and the disman implement is based on internal query with
>  > securityName, then my thoughts should not work, right?
>
>  The only reason that the DisMan Event implementation always
>  uses SNMPv3, is that the Net-SNMP agent cannot handle
>  community-based loopback queries.   (In particular, the access
>  control checks don't like such a setup).
>     There's nothing in the DisMan Event code itself that's tied
>  to SNMPv3 requests - if you're sending a request to a remote
>  target, then you should be able to use SNMPv1 or 2c or 3,
>  as the mood takes you :-)
>
>
>  Dave
>



-- 
Guan-Hong Chen

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