[mrtg] Re: Super SNMP novice. Trying hard to understand.

[Jerry Heidtke]

A little warning about the http.mib on Windows (just to confuse you even
more).

The http.mib from NT 4.0 is not the same as the http.mib from Windows 2000.
Microsoft reassigned some of the OIDs to different meanings between these
versions. If you load the http.mib from NT 4.0 into a tool like getif, then
look at those OIDs on a Windows 2000 server, it won't make much sense.

To get around this, I keep two copies of getif, in folders called GETIFNT4
and GETIFW2K, with the appropriate mib installed in each one.

The snmp standards specify that an OID, once assigned, can never be reused
for something else. Of course, standards don't apply to Microsoft...

Jerry

-----Original Message-----
From: Garth K. Williams [mailto:garth.williams at wtcs.org]
Sent: Wednesday, October 23, 2002 10:08 PM
To: Chris
Cc: Mrtg
Subject: [mrtg] Re: Super SNMP novice. Trying hard to understand.



OK, here goes ....

SNMP is the language that the management station and the device must
understand
COMMUNITY STRING is the main password to allow access to SNMP information
OIDs are the codes to request data or initiate action to or from a device
MIBS are the code keys that identify what each code (OID) means

So, the management station and the targetted device must talk SNMP
and, the management station and the targetted device must have the same
password (community name)
the management station sends an OID to the targetted device, either directly
or through the use of a MIB
and finally, the targetted device replies back to the management station
with the requested data or takes action

In order for you to get IIS information using SNMP, your Windows Server's
SNMP service must load a DLL (NOT a MIB) that "tells" SNMP which OIDs are
associated with IIS.  For NT/2000, these are HTTMIB.DLL (for the WWW
service) and FTPMIB.DLL (for the FTP service).  \WINNT\System32\http.mib is
the code key that contains the OIDs for the WWW service (httpmib.dll).
\WINNT\System32\ftp.mib is the code key that contains the OIDs for the FTP
service (ftpmib.dll).  See the connection?

A MIB browser such as Getif reads the MIBs and allows you to understand what
each OID actually means, and usually these MIB Browsers will allow you the
GET the data by simply selecting the target and the OID (usually in the form
of a more easily read textual description called a fully qualified Object
Definition) and pressing GET.

MRTG allows you to use with the MIB fully qualified OID or the number
#.#.#.#.#.

I hope this helps a little bit.  SIMPLE Network Management Protocol is not
exactly simple.

A book such as the one you mention is a good idea


Garth (snmp4tpc.com)


-----Original Message-----
From: mrtg-bounce at list.ee.ethz.ch [mailto:mrtg-bounce at list.ee.ethz.ch]On
Behalf Of Chris
Sent: Wednesday, October 23, 2002 5:53 PM
To: mrtg at list.ee.ethz.ch
Subject: [mrtg] Super SNMP novice. Trying hard to understand.



Alright I'v gotten pretty far with google and the crappy sites I have found.
Perhaps I am not reading the correct material or I'm just getting things in
bits and piece and in the wrong order.  I think I need O Reilies SNMP book.
Anyway can someone explain to me like I am a 4 year old retarded girl, or
send me to a web site that explains things like I know nothing of computers
because I have become utterly confused.  I am trying to do some simple SNMP
monitor of W2K servers and Linux alike.  http://www.wtcs.org/snmp4tpc/ has
helped a bit but confused as much as it's helped.  I am trying to understand
the difference between OID's and MIB's.  I want to monitor IIS specifically
right now.  I got this cute little program Getif, trying to find the OID's?
for IIS but I get very little information, seems less then I should have.
This is how I understand it.  I got SNMP installed running etc.  Everything
on the system has a specific OID that I can monitor?  Then ya got these MIB
files over here at those do what and go where?  Do I upload the MIB to some
place on the server I want to monitor extra things?  Say a MIB for IIS that
the SNMP service loads when it starts and then when I do a Getif on it or
snmpwalk I should see the OID's for IIS, anon connects, ftp etc?  If your
gonna flame just like give me some yes or no if I'm way off or sorta got the
idea or should just quit my job?  Thanks a thousand times in advanced!


Thank You,

Chris D.
Network Security
Mendo Link, LLC

"An Ounce Of Prevention Is Worth  A Pound Of Cure."
Om Namo Narayanaya

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