FAQ

      Frequently Asked Questions (FAQ) for the UCD SNMP package
      =========================================================
		       FAQ Author: Dave Shield
		ucd-snmp Project Author: Wes Hardaker
		Email: ucd-snmp-coders@ece.ucdavis.edu

TABLE OF CONTENTS
=================

 TABLE OF CONTENTS
 GENERAL
   What is it?
   Where can I get it?
   What documentation is available?
   Are there binaries available?
   What operating systems does it run on?
   What happens if mine isn't listed?
   How do I find out about new releases?
   How can I find out what other people are doing?
   How do I submit a patch or bug report?
   What's the difference between SNMPv1 and SNMPv2?
   What are all these different SNMPv2's anyway?
   Which versions of SNMP are supported in this package?
   Where can I find more information?
 AGENT
   What MIBs are supported?
   How do I add a MIB?
   How do I add a MIB to the tools?
   How do I add a MIB to the agent?
   How do I add functionality?
   What traps are sent by the agent?
   When I run the agent it runs and then quits without staying around. Why?
 TECHNICAL
   How do I write C code to integrate with the agent?
   What ASN.1 parser is used?
   How does the agent fetch the value of a variable from the system?
   What is the Official Slogan of the ucd-snmp-coders list?
 PROBLEMS
   How come ever since version 3.2 my mib files are no longer read?
   What's this about a "party database", when I try to send a query?
   Why can't I see values in the UCDavis 'extensible' tree?
   Why can't I see values in the <INSERT ENTERPRISE HERE> tree?
   I've done that, and I still can't see the values. Why not?
   I've done that, and I'm *still* not getting anything back. Why not?
   I've done that, but I'm *still* getting "sub-identifier not found:" Grrr!
   The agent is complaining about 'snmpd.conf'.  Where is this?
   What does "klread:  bad address" mean?
   What does "nlist err:  wombat not found" (or similar) mean?
   How about "Can't open /dev/kmem"?
   Or "sendto: permission denied" ?
   I'm using the Perl SNMP module, and get something about "bad free"?
   I can't load any of the mib files, and they seem to be missing
       the first two characters of the filename.  What's happening?
   How do I compile with 'gcc' instead of 'cc'?
   But gcc doesn't compile it successfully on my new Solaris system. Why not?
   I cannot set any variables in the MIB.
   Sometimes I seem to get the wrong answers.  Why?


GENERAL
=======

What is it?
----------

  - Various tools relating to the Simple Network Management Protocol
    including:

	* An extensible agent
	* An SNMP library
	* tools to request or set information from SNMP agents
	* tools to generate and handle SNMP traps
	* a version of the unix 'netstat' command using SNMP

    This package is originally based on the Carnegie Mellon University
    SNMP implementation (version 2.1.2.1)


Where can I get it?
------------------

  - ftp://ftp.ece.ucdavis.edu/pub/snmp/ucd-snmp.tar.gz
  - ftp://sunsite.cnlab-switch.ch/mirror/ucd-snmp/ucd-snmp.tar.gz
  - ftp://ftp.win.or.jp/pub/network/snmp/ucd-snmp/ucd-snmp.tar.gz


What documentation is available?
-------------------------------

	This FAQ (!)
	README
	INSTALL
	PORTING
	EXAMPLE.conf
	man pages for the individual tools, files and the API

      Most of this documentation is also available on our web page,
        as well as mailing list acrchives:
        http://www.ece.ucdavis.edu/ucd-snmp

Are there binaries available?
----------------------------

  - Nope, sorry.

	The distribution ought to compile cleanly and run
	on a range of systems (see the next answer).
	See the file INSTALL for more details.


What operating systems does it run on?
-------------------------------------

	* HP-UX 9.07, 9.05, 9.03, 9.01 on HPPA 1.1 systems
	* HP-UX 10.20, 10.10, 10.01 on HPPA 1.1 systems
	* Ultrix 4.5, 4.4, 4.3, 4.2 on DEC MIPS systems
	* Solaris 2.6, 2.5.1, 2.5, 2.4, 2.3 on Sun SPARC systems
	* Solaris 2.5 on x86 systems
	* SunOS 4.1.4, 4.1.3, 4.1.3, 4.1.2 on Sun SPARC systems
	* OSF 4.0, 3.2 on DEC Alpha systems
	* NetBSD 1.3alpha, 1.2.1, 1.2, 1.1, 1.0 on all? systems
	* FreeBSD 3.0, 2.2.2, 2.2 on all? systems
	* BSDi 2.1 on all? systems
	* Linux 2.1, 2.0, 1.3 on all? systems
        * AIX 4.1.5, 3.2.5 on all? systems

  The applications (though not necessarily the agent) run on the
  following systems:

        * Irix 6.2
        * Windows95
        * Windows NT


What happens if mine isn't listed?
---------------------------------

  It's worth trying anyway, particularly if the system is based
	around the BSD kernel.  If it seems to work correctly,
	let us know so that we can update the list above.
	If it doesn't work, let us know and we'll try to help.
  If the agent almost compiles, but certain files in the
	agents/mibgroup directory fail, you can try omitting those
	modules by re-running configure with the flag
		--with-out-mib-modules="list"
	You'll then need to re-compile.
  Either way, try it and let us know how you get on (see below for how).
	

How do I find out about new releases?
------------------------------------

  There is a mailing list for these announcements
  	ucd-snmp-announce@ece.ucdavis.edu
  To be added to (or removed from) this list, send a message
  to the address 'ucd-snmp-announce-request@ece.ucdavis.edu'
  with a subject line of 'subscribe' (or 'unsubscribe' as appropriate).

  Major code revisions may be announced more widely (e.g. on the
	SNMP mailing lists, or comp.protocols.snmp) but this list is
  the most reliable way to keep in touch with the status of this package.


How can I find out what other people are doing?
----------------------------------------------

  There is a general purpose discussion list
  	ucd-snmp@ece.ucdavis.edu
  To be added to (or removed from) this list, send a message
  to the address 'ucd-snmp-request@ece.ucdavis.edu'
  with a subject line of 'subscribe' (or 'unsubscribe' as appropriate).

  There's not a great deal of traffic at the moment, but you can
  always try to do something about that!
  

How do I submit a patch or bug report?
-------------------------------------

   There is a script that you can use to submit a bug report.
   This allow you to describe the problem you're having, and
	includes various pieces of information about your system
	that are useful in trying to track down the problem.

   Alternatively, you can send a message to
		'ucd-snmp-coders@ece.ucdavis.edu'
	containing a description of the problem, and as much other
	relevant details as you can. Useful information includes the
	version of the package that you've been working with, the output
	of the command 'uname -a', the precise command that triggers the
	problem and a copy of the output it produces.

   We can't promise to be able to solve the problem, but we'll
	certainly try and help.


   If you're trying to port the package to a new system, the output
	of the command 'make -k' is a good starting indicator of where
	the bulk of the work is likely to be needed.

   If you're reporting success on a new system, please let us know
   both details of the hardware you're using, and what versions of
   the operating system you've tried it on.  The entry 'host' in
   the file 'config.status' will show this information.
	Oh, and congratulations!


What's the difference between SNMPv1 and SNMPv2?
-----------------------------------------------
What are all these different SNMPv2's anyway?
--------------------------------------------


  A full description is probably beyond the scope of this FAQ.
  Very briefly, the original protocol and framework was described
  in RFCs 1155-1157, and is now known as SNMPv1.

    Practical experience with this showed up various problems and
  deficiencies wih this, and a revised framework was developed to
  try and address these.  This was described in RFCs 1441-1452, and
  is known as "SNMPv2 classic".
  The changes proposed include:

	* new ways of defining information (MIB structure)
		(SMI, Textual conventions, conformance statements)
	* new protocol packet types and transport mappings
	* new mechanisms for administration and security
	* mechanisms for remote configuration

  Unfortunately, while many of these were generally accepted, there
  was still some disagreement in these last two areas, security/admin
  and remote configuration.  This resulted in a number of variants and
  alternative proposals:

	SNMPv2c		Contains the new protocol and MIB structure elements,
			using the existing SNMPv1 administration structure.
			This is the agreed SNMPv2 standard (described in
			RFCs 1901-1908), superseding SNMPv2 classic, and is
			known as "Community-based SNMPv2" or simply "SNMPv2".


	SNMPv2 usec	} Alternative proposals to address the
	SNMPv2*		} limitations of SNMPv1 administration
			} These are both super-sets of SNMPv2c

			
	SNMP-NG		A recent attempt to reach agreement between
			the proponents of usec and v2star.

	SNMPv3		The formal successor to SNMP-NG, currently being
			active developed, and aiming to produce Proposed
			Standards for the next generation of core SNMP
			functions in the very near future.


Which versions of SNMP are supported in this package?
----------------------------------------------------

  This package currently supports the original SNMPv1, SNMPv2 classic
  (i.e. RFCs 1441-1452, and referred to as "SNMPv2 historic)), and
  Community-based SNMPv2 (i.e. RFCs 1901-1908).
    The agent will respond to requests using any of these protocols,
  and all the tools take a command-line option to determine which
  version to use.

    The group is not currently tracking the SNMPv3 development (as far
  as I know).  When these standards emerge, it is likely that we will
  seek to implement them as soon as possible.


Where can I find more information?
---------------------------------

  There are a number of sites with network management information on
  the World Wide Web. Two of the most useful are

      http://netman.cit.buffalo.edu/index.html
      http://wwwsnmp.cs.utwente.nl/

  There are two Usenet newsgroups which are relevant.
	'comp.dcom.net-management'
		which discusses general issues relating to network management
	'comp.protocols.snmp'
		which is specifically concerned with use of SNMP in particular

  (though there is a large overlap between these two groups).
  The SNMP group also has an FAQ (split into two parts) which discusses more
  general issues related to SNMP, including books, software, other sites,
  how to get an enterprise number, etc, etc.
  This is available from

      ftp://rtfm.mit.edu/pub/usenet/comp.protocols.snmp/

  or via either of the two Web sites above.



AGENT
=====

What MIBs are supported?
-----------------------

  The following MIBs are supported (at least in part):

	- MIB-2  General network statistics (RFC 1213)
	- UCD agent extensions
		(processes, disks, memory, load average,
		 shell commands, error handling)
	- SNMPv2 Party MIB (RFC 1447 - now 'historic')
	- SNMPv2 Manager-to-Manager MIB (RFC 1451 - now 'historic')
	- SMUX implementation (RFC 1227) for communicating with 'gated'
		(plus routing protocols BGP, OPSF & RIP2 - RFCs 1657, 1724 & 1850)
	- Host Resources (RFC 1514) skeleton implementation



How do I add a MIB?
------------------

  This is actually two separate questions, depending on whether you
  are referring to the tools, or the agent (or both).
    See the next two questions.



How do I add a MIB to the tools?
-------------------------------

  The tools only really use the MIB files for translating between
  numeric and textual forms for queries and responses.  They will
  operate quite happily without any MIB files at all, as long as
  you are prepared to work with numeric OIDs throughout.

  The tools look in a predefined directory (usually PREFIX/share/snmp/mibs)
  and regard any file held there as defining a MIB module or modules.
  Adding translation ability for a new MIB moule is simply a
  matter of placing a file defining the MIB in this directory, and
  defining a suitable environment to tell the tools about it.
    (See the first question under 'PROBLEMS' for more details).

  The tools can then be used to communicate with any agent that
  implements the relevant MIB modules.

  The UCD agent, however, does not use these MIB text files at all, and
  will work quite happily without them.  (Actually it needs to find the
  main MIB file, though it doesn't do anything with it!).  The values
  returned by the agent are simple numeric (or string) responses, and
  the syntax and scope of the variables supported are hard-coded into
  the implementation.  The MIB text files are only used to translate
  these responses into more meaningful terms.



How do I add a MIB to the agent?
-------------------------------
How do I add functionality?
--------------------------

  Unfortunately, adding a file to the MIB directory does not automatically
  extend the functionality of the agent to include this MIB.  (Would that
  life were so simple).  In fact, the agent makes little or no use of
  these files, and will work quite happily without them.
  All the information about the syntax and scope of the variables supported
  is hardwired into the iplementation of the agent.

  There are three ways to add funcionality for a new MIB to the agent.

  Firstly, it is possible that the agent distribution already includes
  the desired functionality, but this has simply not been configured in
  to the running version.  This is done using the configure option
		--with-mib-modules="list"
  then recompiling the agent.
  Note that some functionality concerned with monitoring and managing
  unix hosts is included in the UCD extension modules, which are located
  within the 'private' branch of the MIB tree.  See the third question
  under PROBLEMS for more details of how to access these.

  Secondly, it is possible for the agent to run commands or shell scripts
  in response to queries.  These can optain and report the necessary
  information, or perform actions as required.
  Detailed information and examples are provided in the snmpd(1) and
  snmpd.conf(5) manual pages, and the EXAMPLE.conf file.

  Thirdly, the agent itself can be extended to support additional MIB
  groups, by writing the necessary C code.  This is covered further in
  the 'TECHNICAL' section below.

    Note that there is effectively no difference between 'pass-through'
  MIB support, and modules implemented within the agent itself. Tools
  querying the agent will see a single MIB structure.
 


What traps are sent by the agent?
--------------------------------

  The agent can be configured to send a 'coldStart(0)' trap when it first
  starts up.  The destination to send the trap to, and the community name
  to use, are set in the snmpd.conf file
    ('trapsink' and 'trapcommunity' respectively - note both are required)

    The agent can also be configured to send 'authenticationFailure(4)'
  traps when it receives SNMPv1 requests using a community name that is
  not recognised.
    This is done with the snmpd.conf entry 'authtrapsenable 1'.
    


When I run the agent it runs and then quits without staying around. Why?
-----------------------------------------------------------------------

  The first question is, are you certain that this is what is happening?

  The normal operation of the agent is to 'fork' itself into the
  background, detaching itself so that it will continue running even
  when you log out, and freeing the command line for subsequent use.
  This looks at first sight as if the agent has died, but using 'ps'
  to show all processes should reveal that the agent is still running.

  To prevent this behaviour, such as when attempting to debug the
  agent, you can start it with the '-f' flag.  This suppresses the
  fork, and the agent will run as a 'normal' command.

  On the other hand, if 'ps' shows that the agent is not running, then
  this is an error, and probably show that something went wrong in
  starting the agent up.  See under 'PROBLEMS' for more advice.  



TECHNICAL
=========

How do I write C code to integrate with the agent?
-------------------------------------------------

  At the moment, the only technique for integrating external C code
  with the agent (as opposed to using the 'pass-through' shell
  extensibility mentioned above) is to implement it within the agent itself.

  The implementation of the agent has recently been re-organised
  to make it easier to incorporate new MIB groups.  The relevant code
  is held in the directory 'agent/mibgroup', with one file (plus
  header) per group in most cases.  The README file in that directory
  gives more information as to the structure of these files, and how
  to add a new group. 
  Contact the list 'ucd-snmp-coders@ece.ucdavis.edu' for further advice.

  It is hoped to implement some form of proxy mechanism (such as the
  agentx protocols) once the specification for these have settled, and
  someone gets around to writing the necessary code.


What ASN.1 parser is used?
-------------------------

  The parser used by both the agent and client programs is coded by hand.
  This parser has recently been re-vamped to allow control of which of 
  the available MIBs should be included, and to handle duplicate object
  subidentifiers.
    The source code can be found in the snmplib directory (in 'parse.c'),
  and the parser is usually bundled into the library 'libsnmp.a'


How does the agent fetch the value of a variable from the system?
----------------------------------------------------------------

  Much of the information is extracted from kernel memory - usually
  by seeking to the appropriate location and reading the structures
  directly.
    Some systems provide cleaner interfaces to such kernel information
  (it would be hard to think of a less clean interface!), via ioctl()
  calls or similar system routines and these mechanisms are usually used
  in preference.


What is the Official Slogan of the ucd-snmp-coders list?
-------------------------------------------------------

  "The current implementation is non-obvious and may need to be improved."
	(with thanks to Rohit Dube)



PROBLEMS
========

Why aren't my mib files read in any more?
-----------------------------------------

  As from version 3.2, the parser has been re-written.  One effect of
  this is that only a specified set of MIB modules are read in by
  the tools by default.  This list can be set in a number of ways:

    The tools have a default list compiled in, which can be set
  using the configure option
		--with-mibs="list"
  and recompiling the tools.

    The environmental variable 'MIBS' will be taken as a list of
  module names (separated by colons) to be read in, instead of (or as
  well as) the default list.  Note that any modules these rely on will
  be read in automatically, without needing to be listed explicitly.

    The environment variable 'MIBFILES' will be taken as a list of
  filenames, containing MIB modules to be read in (in addition to those
  included by 'MIBS' and/or the default list).  Again, any modules these
  rely on will also be loaded in automatically.
    The names listed in this variable can be anywhere in the filesystem,
  though any implicitly loaded modules must be present in the standard
  location(s). 

    Finally, if the environmental variable 'MIBS' has the special
  value "ALL", then the tools will load in every module present in
  the module directory (or directories).

    The location where the tools look for MIB module files is compiled
  into the tools. This can also be set using the environmental
  variable 'MIBDIRS', being a (colon-seperated) list of directories
  containing MIB files. 

  See the 'mib_api(3)' man page for more details.


I'm getting answers, but they're all numbers. Why?
-------------------------------------------------

  This is actually the same as the previous question.  Because the tools
  no longer read in every MIB module they can find, it is quite possible
  for results from an agent to refer to modules that have not been loaded
  (particularly with GETNEXT requests, or when walking a tree).
     The tools will report the answer quite correctly, but won't translate
  identifiers and enumerations into readable strings.  To fix this, use
  the environmental variables MIBS or MIBFILES to read in the relevant
  module files.
    This does assume you have these files installed properly.  There's not
  a great deal we can do if you haven't.


What's this about a "party database", when I try to send a query?
----------------------------------------------------------------

  Previous releases of these tools sent SNMPv2 (classic) queries,
  which relied on party configuration information being available.
    With the current release, by default queries now use SNMPv2c,
  which does not need any such party configuration.

    In either case, it is possible to specify the use of SNMPv1
  instead, by giving the application the option "-v 1".
 

Why can't I see values in the UCDavis 'extensible' tree?
-------------------------------------------------------

  The extensible tree is designed to report things you ask it to report
  on.  If you don't declare anything in the snmpd.conf file for it to
  monitor, it will not report anything.  See the snmpd.conf manual page
  and the EXAMPLE.conf file for details no configuring the agent.

Why can't I see values in the <INSERT ENTERPRISE HERE> tree?
-----------------------------------------------------------

  Normally, the tools assume that any object ID specified is
  a full path, starting from the 'mib-2' node of the overall
  MIB tree.  So if you perform an 'snmpwalk' on an agent, without
  specifying a starting point, it will return just the values in
  the 'mib-2' tree.

    If you wsh to examine anything under the 'private.enterprises'
  branch (or anywhere else in the MIB structure) you will need to
  inform the tools appropriately.   There are two ways to do this:

  First, you can give the full specification, starting from the root
  of the tree - e.g:

	.iso.org.dod.internet.private.enterprises.ucdavis

  Note the initial dot - this is important!

  Alternatively, you can define the environmental variable PREFIX,
  to specify where to start looking for ( non-fully specified) objects.
  This can be done by the command
							(C shell family)
	setenv PREFIX  .iso.org.dod.internet.private.enterprises.ucdavis
  or
							(Bourne shell family)
	PREFIX=.iso.org.dod.internet.private.enterprises.ucdavis
	export PREFIX

  after which, the following example should work:

	snmpwalk -v 1 localhost public processes


I've done that, and I still can't see the values. Why not?
---------------------------------------------------------

    Another possibility is that there is a clash of names
  somewhere within the MIB tree.  Try running the command
  'snmptranslate -x zzz' which will inform you of any duplicates,
  or other similar problem.

    This should be less of a problem with the new parser, which
  now handles duplicate identifier names, though inconsistent
  case in labels for the same node still confuse the poor darling.


I've done that, and I'm *still* not getting anything back. Why not?
------------------------------------------------------------------

  Another possibility is that the agent you are querying is simply not
  responding.  Try contacting it with a "reliable" query.
  A good test is to do an 'snmpwalk' on the 'system' sub-tree.

    Or it may be that the agent just doesn't implement the MIB
  module that you're interested in.  Or it does, but is falling over
  (software with bugs in - shock horror!)
    Try doing an 'snmpwalk' starting somewhere above the offending bit
  of the MIB tree, and seeing how far it gets.


I've done that, but I'm *still* getting "sub-identifier not found:" Grrr!
------------------------------------------------------------------------

  If a "general" snmpwalk shows the entry, but asking for it more
  specifically gives a "sub-identifier not found:" error, then that's
  a slightly different problem.

    The tools assume that the object ID they are given is a full path
  starting from 'mib-2' (or wherever you have set PREFIX to).
  You can't simply give the final sub-identifier, and expect the tools
  to find the relevant node.  (Well, you can, but you'll be disappointed).
    You need to specify the intermediate sub-identifiers as well.

    For example
		snmpget myhost public sysUpTime.0
                                                     will fail, while
		snmpget myhost public system.sysUpTime.0
                                                          will work.
  There are plans to include this "random access" feature (for unique
  names at least), but this is not yet available.


The agent is complaining about 'snmpd.conf'.  Where is this?
-----------------------------------------------------------

  It doesn't exist in the distribution as shipped.  You need to
  create it to reflect your local requirement.
    To get started, you can either just create this as an empty file,
  or try copying the EXAMPLE.conf file which will use some of the UCD
  extensions.  See the snmpd.conf(5) manual page for further details.


What does "klread:  bad address" mean?
-------------------------------------

  This means that the agent was unable to extract some of the
  necessary information from the kernel structures.  This is
  possibly due to:
	- either looking in the wrong place for kernel information
		(check the value of KERNEL_LOC)
	- an error in the implementation of part of the MIB tree
		for that architecture.  Try and identify which
		OID is generating the error, and contact the
		list 'ucd-snmp-coders@ece.ucdavis.edu'


What does "nlist err:  wombat not found" (or similar) mean?
----------------------------------------------------------

  This means that the agent wasn't able to locate one of the
  kernel structures it was looking for.  This may or may not
  be important - some systems provide alternative mechanisms
  for obtaining the necessary information - Solaris, for example,
  can produce a whole slew of such messages, but still provide
  the correct information.
    This error only occurs if you have used the flag
  '--enable-debugging' as part of the initial configuration.
  Reconfigure the agent with '--disable-debugging' and these
  messages will disappear.


How about "Can't open /dev/kmem"?
--------------------------------

  This device is normally restricted to just being accessible by root
  (or possibly by a special group such as 'kmem' or 'sys').  The agent
  must be able to read this device to obtain the necessary information
  about the running system.
    Check that the agent was started by root, and is running with UID 0
  (or suitable GID if appropriate)
 

Or "sendto: permission denied"?
------------------------------

  This was due to a minor problem in setting network addresses, which
  has now been fixed.  If you are seeing this error, please install the
  most recent version of the UCD snmp tools.


I'm using the Perl SNMP module, and get something about "bad free"?
------------------------------------------------------------------

  This problem has also been fixed in the most recent release of the
  UCD SNMP tools.  In general, if you experience any problem like this,
  try checking to see if there's a newer release first.
    In particular, the recent changes in the way MIB files are parsed
  requires Perl SNMP-1.6 or later.


I can't load any of the mib files, and they seem to be missing
the first two characters of the filename.  What's happening?
-----------------------------------------------------------

  This is a problem experienced with Sun systems when the tools have
  been compiled with a mixture of BSD and Solaris environments.
  You'll need to re-configure and compile the tools, making sure that
  '/usr/ucb' is not in your PATH (or at least comes at the end).


How do I compile with 'gcc' instead of 'cc'?
-------------------------------------------

  Set the environmental variable 'CC' to have the value 'gcc' before
  running the configure script.


But gcc doesn't compile it successfully on my new Solaris system. Why not?
-------------------------------------------------------------------------

  Whenever you upgrade the operating system under Solaris, you need to
  reinstall gcc, and run the 'fixincludes' script.  (This is probably
  a sensible step to take when you upgrade any operating system).
    Under Solaris 2.6, there is also a bug in the gcc 'fixinc.sv4' script.
  This needs an additional line as follows:

*** fixinc.svr4.cln     Thu Jun 15 22:03:29 1995
--- fixinc.svr4 Tue Nov 25 09:47:57 1997
***************
*** 191,191 ****
--- 191,192 ----
          s/__STDC__ - 0 == 0/!defined (__STRICT_ANSI__)/g
+         s/__STDC__ - 0 == 1/defined (__STRICT_ANSI__)/g


I cannot set any variables in the MIB.
-------------------------------------

  There are three possible reasons for this:

  The majority of MIB variables are "read-only" and cannot be changed.

  Of those that can in principle be changed, only a few have been
  implemented as such in this agent.  Currently, most (if not all)
  of these are contained within the 'system' sub-tree, relating to
  general contact information.
    
  With the distribution as shipped, the community name "private" must
  be used to set these values.  This can be changed by setting the
  second community string (via the snmpd.conf entry "community 2 newstring").
  Note that the (first) community string "public" can *not* be used
  to set variables.
  

Sometimes I seem to get the wrong answers.  Why?
-----------------------------------------------

  Many of the variables in the basic MIB-2 tree require information
  that is not easily available in the common Unix kernels.  In the
  absence of anything better, the agent returns hardwired 'null'
  values.  The items affected are:

	interface.ifType		other(1)
	interface.ifSpeed		1
	interface.ifLastChange		0
	interface.ifInNUCastPkts	0
	interface.ifInDiscards		0
	interface.ifInUnknownProtos	0
	interface.ifOutNUCastPkts	0
	interface.ifSpecific		Null OID

	ip.ipInUnknownProtos		0
	ip.ipInDiscards			0
	ip.ipOutRequests		0
	ip.ipOutDiscards		0
	ip.ipFragOKs			0
	ip.ipFragFails			0
	ip.ipFragCreates		0
	ip.ipRouteDiscards		0
	ipAddrEntry.ipAdEntReasmMaxSize	-1
	ipRouteEntry.ipRouteAge		0

	tcp.tcpMaxConn			-1
	tcp.tcpOutRsts			0

	udp.udpInDatagrams		0
	udp.udpNoPorts			0
	udp.udpOutDatagrams		0


  The following variables have 'likely guess' values, that are not
  necessarily strictly accurate.
  The SNMP protocol standards (RFCs 1157 and 1905) could actually be
  taken to imply that the agent should return a 'genErr' in these cases.


	interface.ifInOctets		guess based on # of packets
	interface.ifInUCastPkts		includes non-unicast packets
	interface.ifOutOctets		guess based on # of packets
	interface.ifOutUCastPkts	includes non-unicast packets

	ip.ipInDelivers			Doesn't handle fragments properly
	ip.ipReasmOKs			Assumes fragments are complete datagrams
	ipRouteEntry.ipRouteProto	local(2) or icmp(4)

	tcp.tcpRtoAlgorithm		vanJ(4)   (probably correct!)


  The following variables are simply not implemented according to specification

	tcp.tcpAttemptFails		} actually counting
	tcp.tcpEstabResets		} something different
	tcp.tcpOutResets		}


  Some systems may return the correct information for these values.
  Systems that are believed to have corrected some of these are as follows:

	*  FreeBSD & BSDi provide correct interface statistics
	*  Solaris, Linux & HP-UX provide correct statistics throughout
		(though Solaris may need a kernel patch to
		 support interface octet counts).