Re: Problem to determinate SNMP version

>>>>> On Tue, 25 Apr 2006 16:51:45 +0200, [email protected] said:

mickb> Here's the problem : as there is no specific SNMP query
mickb> returning supported version(s), I have the idea to use the
mickb> behavior of the SNMP::Session constructor which returns an
mickb> object reference if connection successful or undef in case of
mickb> error.  Unfortunately, it doesn't work in the expected way. I
mickb> have made a test on an old switch supporting only SNMP v1. When
mickb> I query it with v3, OK : SNMP::Session->new returns
mickb> "undef". But when I query it with v2c, how surprising :
mickb> SNMP::Session->new returns me a descriptor... :(

It's actually fairly easy to determine if something supports SNMPv3
(and has engineID probing turned on).  However, it's impossible to
tell if something supports SNMPv1 without simply trying it.  Thus, we
return a session object if v1/v2c are in use but not for v3 if it
couldn't at least talk to the agent (this may change in the future so
we always return on).

The only way to know for sure is to create the session and try to
query a object that you know exists on all the machines (sysUpTime.0
is a good choice).

mickb> This situation is quite annoying for me. Is this a bug ? Or, if
mickb> anyone has a suggestion for a more reliable solution to obtain
mickb> version, please tell me.

It's a design decision of the protocol; nothing we can do to fix it
(aside from adding a local "test the session" api which would
functionally do what I described above).
-- 
Wes Hardaker
Sparta, Inc.


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