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From: Joe Marzot <[email protected]>
Newsgroups: comp.lang.perl.announce,comp.lang.perl.modules
Subject: ANNOUNCE: SNMP-1.7
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Date: 2 Jan 1998 23:51:17 GMT
Organization: Bay Networks, Inc.
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attached is the README from the latest release of the perl5 SNMP
extension module.

ftp:/ftp.corpeast.baynetworks.com/netman/snmp/perl5/SNMP-1.7.tar.gz

-GSM


------
                    Perl5 SNMP Extension Module
                      for the UCD SNMP Library
               G.S. Marzot ([email protected])

Contents:
  Introduction:
  Availability:
  Supported Platforms:
  Installation:
  Operational Description:
  Trouble Shooting:
  Acknowledments:
  History:


Introduction:

This is a Perl5 extension module which provides an interface to the
UCD SNMP client toolkit. The UCD SNMP Library is based on version
2.1.2.1 of the CMU SNMP Library and has incorporated many bugfixes and
enhancements. For information on the UCD SNMP Library see the
documentation provided with the UCD SNMP distribution.

(NOTE: In previous releases this module was compatible with both the
UCD and CMU SNMP libraries. Starting with Perl5/SNMP-1.7 this module
will only work with the UCD SNMP Library 3.3.1 or later due to
dependence on new features)

Availability:

The most recent release of the UCD SNMP Libray can be found at:
ftp://ftp.ece.ucdavis.edu/pub/snmp/ucd-snmp.tar.gz

The most recent release of the Perl5/SNMP module can be found at:
ftp:/ftp.corpeast.baynetworks.com/netman/snmp/perl5/SNMP.tar.gz
(as well as the usual perl archives, CPAN)

Supported Platforms:
       SunOS 4.1.x
       Solaris 2.x
       Linux 1.2.x, 2.0.x
       Many other UNIX variants
       Win95/NT   ***NEW***

Installation:

build and install ucd-snmp-3.3.1 or later

note: you should ensure that any previous ucd-snmp installation is
completely removed.

perl Makefile.PL
make
make test
make install

note: for 'make test' to succeed you should ensure that an agent running
(e.g., /usr/local/sbin/snmpd)

Operational Description:

The basic operations offered by SNMP are provided through an object
oriented interface for modularity and ease of use. The primary class
is SNMP::Session which is implemented as a blessed hash
reference. This class supplies 'get', 'getnext', 'set', 'fget', and
'fgetnext' method calls. All calls are currently blocking/synchronous
(i.e., they must receive a response or timeout before control is
returned to the caller - an asyncronous implementation is very high on
the TODO list). The methods take a variety of input argument formats
(see below).

A description of the fields which can be specified when an
SNMP::Session object is created follows:

SNMP::Session
public:
DestHost    - default 'localhost', hostname or ip addr of SNMP agent
Community   - default 'public', SNMP community string (used for both R/W)
Version     - default '1', [2 (same as 2c), 2c, 3 (not implemented)]
RemotePort  - default '161', allow remote UDP port to be overriden
Timeout     - default '1000000', micro-seconds before retry
Retries     - default '5', retries before failure
RetryNoSuch - default '1', 'get' request NOSUCH errors in the pdu will
              be repaired, removing the varbind in error, and resent -
              undef will be returned for all NOSUCH varbinds, setting
              to '0' disables this feature and the entire get request
              will fail on any NOSUCH error (applies to v1 only)
VarFormats  - default 'undef', used by 'fget[next]', holds an hash
              reference of output value formatters, (e.g., {<obj> =>
              <sub-ref>, ... }, <obj> must match the <obj> and format
              used in the get operation. A special <obj>, '*', may be
              used to apply all <obj>s, the supplied sub is called to
              translate the value to a new format. The sub is called
              passing the Varbind as the arg
TypeFormats - default 'undef', used by 'fget[next]', holds an hash
              reference of output value formatters, (e.g., {<type> =>
              <sub-ref>, ... }, the supplied sub is called to translate
              the value to a new format, unless a VarFormat mathces first
              (e.g., $session->{TypeFormats}{INTEGER} = \&mapEnum();)
UseLongNames - defaults to the value of SNMP::use_long_names at time
              of session creation. set to non-zero to have <tags>
              for 'getnext' methods generated preferring longer Mib name
              convention (e.g., system.sysDescr vs just sysDescr)
UseSprintValue - defaults to the value of SNMP::use_sprint_value at time
              of session creation. set to non-zero to have return values
              for 'get' and 'getnext' methods formatted with the libraries
              sprint_value function. This will result in certain data types
              being returned in non-canonical format NOTE: values returned
              with this option set may not be appropriate for 'set' operations
              (see discussion value formats in <vars> description section)
UseEnums    - defaults to the value of SNMP::use_enums at time of session
              creation. set to non-zero to have integer return values
              converted to enumeration identifiers if possible, these values
              will also be acceptable when supplied to 'set' operations
ErrorStr    - read-only, holds the error message assoc. w/ last request
ErrorNum    - read-only, holds the snmp_err or staus of last request
ErrorInd    - read-only, holds the snmp_err_index when appropriate

private:
DestAddr    - internal field used to hold the translated DestHost field
SessPtr     - internal field used to cache a created session structure

methods:
new(<fields>)   - Constructs a new SNMP::Session object. The fields are
                  passed to the contructor as a hash list
                  (e.g., $session = new SNMP::Session(DestHost => 'foo',
                  Community => 'private');), returns an object reference
                  or undef in case of error.
update(<fields>)- Updates the  SNMP::Session object with the values fields
                  passed in as a hash list (similar to new(<fields>))
get(<vars>)     - do SNMP GET, multiple <vars> formats accepted,
                  updates <vars> with value(s) and type(s), returns
                  retrieved value(s)
fget(<vars>)    - do SNMP GET like 'get' and format the values according
                  the handlers specified in $sess->{VarFormats} and
                  $sess->{TypeFormats}
getnext(<vars>) - do SNMP GETNEXT, multiple <vars> formats accepted,
                  returns retrieved value(s), <vars> passed as arguments are
                  updated to indicate next lexicographical <obj>,<iid>,<val>,
                  and <type> NOTE: simple string <vars>,(e.g., 'sysDescr.0')
                  form is not updated
fgetnext(<vars>)- do SNMP GETNEXT like getnext and format the values according
                  the handlers specified in $sess->{VarFormats} and
                  $sess->{TypeFormats}
set(<vars>)     - do SNMP SET, multiple <vars> formats accepted,
                  the value field in all <vars> formats must be in a canonical
                  format (i.e., well known format) to ensure unambiguous
                  translation to SNMP MIB data value (see discussion of
                  canonical value format <vars> description section),
                  returns snmp_errno
getbulk(<non-repeaters>, <max-repeaters>, <vars>)
                - * Not Implemented *
trap()          - * Not Implemented *

Acceptable variable formats:
<vars> may be one of the following forms:

SNMP::VarList:  - represents an array of MIB objects to get or set,
                  implemented as a blessed reference to an array of
                  SNMP::Varbinds, (e.g., [<varbind1>, <varbind2>, ...])

SNMP::Varbind:  - represents a single MIB object to get or set, implemented as
                  a blessed reference to a 4 element array;
                  [<obj>, <iid>, <val>, <type>].
                  <obj>  - one of the following forms:
                         1) leaf identifier (e.g., 'sysDescr') assumed to be
                            unique for practical purposes
                         2) fully qualified identifier (e.g.,
                            '.iso.org.dod.internet.mgmt.mib-2.system.sysDescr')
                         3) fully qualified, dotted-decimal, numeric OID (e.g.,
                            '.1.3.6.1.2.1.1.1')
                  <iid>  - the dotted-decimal, instance identifier. for
                           scalar MIB objects use '0'
                  <val>  - the SNMP data value retrieved from or being set
                           to the agents MIB. for (f)get(next) operations
                           <val> may have a variety of formats as determined by
                           session and package settings. However for set
                           operations the <val> format must be canonical to
                           ensure unambiguous translation. The canonical forms
                           are as follows:
                           OBJECTID => dotted-decimal (e.g., .1.3.6.1.2.1.1.1)
                           OCTETSTR => perl scalar containing octets,
                           INTEGER => decimal signed integer (or enum),
                           NETADDR => dotted-decimal,
                           IPADDR => dotted-decimal,
                           COUNTER => decimal unsigned integer,
                           COUNTER64  => decimal unsigned integer,
                           GAUGE,  => decimal unsigned integer,
                           UINTEGER,  => decimal unsigned integer,
                           TICKS,  => decimal unsigned integer,
                           OPAQUE => perl scalar containing octets,
                           NULL,  => perl scalar containing nothing,


                  <type> - SNMP data type (see list above), this field is
                           populated by 'get' and 'getnext' operations. In
                           some cases the programmer should populate this
                           field when passing to a 'set' operation. this
                           field need not be supplied when attribute
                           indicated by <tag> is already described by loaded
                           Mib modules. for 'set's, if a numeric OID is used
                           and the object is not currently in the loaded Mib,
                           the <type> fileds must be supplied

simple string   - light weight form of <var> used to 'set' or 'get' a
                  single attribute without constructing an SNMP::Varbind.
                  stored in a perl scalar, has the form '<tag>.<iid>',
                  (e.g., 'sysDescr.0'). for 'set' operations the value
                  is passed as a second arg. NOTE: This argument form is
                  not updated in get[next] operations as are the other forms.

SNMP package variables and functions:

$SNMP::VERSION       - the current version specifier (e.g., 1.7)

$SNMP::auto_init_mib - default '1', set to 0 to disable automatic reading
                       of the MIB upon session creation. set to non-zero
                       to call initMib at session creation which will result
                       in MIB loading according to UCD env. variables (see
                       man mib_api)

$SNMP::verbose       - default '0', verbosity level, 0 => no output

$SNMP::use_long_names - default '0', set to non-zero to enable the use of
                       longer Mib identifiers. see translateObj. will also
                       influence the formatting of <tag> in varbinds returned
                       from 'getnext' operations. Can be set on a per session
                       basis (UseLongNames)

$SNMP::use_sprint_value - default '0', set to non-zero to enable formatting of
                       response values using the snmp libraries sprint_value
                       function. can also be set on a per session basis (see
                       UseSprintValue) NOTE: returned values may not be
                       suitable for 'set' operations

$SNMP::use_enums     - default '0',set non-zero to return values as enums and
                       allow sets using enums where appropriate. integer data
                       will still be accepted for set operations. can also be
                       set on a per session basis (see UseEnums)

&SNMP::setMib(<file>) - allows dynamic (re?)parsing of the mib and explicit
                       specification of mib file independent of enviroment
                       variables. called with no args acts like initMib,
                       loading MIBs indicated by environment variables (see
                       ucd mib_api docs). passing non-zero second arg
                       forces previous mib to be freed and replaced
                       (note: second arg not working since freeing previous
                        Mib is more involved than before).

&SNMP::initMib()     - calls library init_mib function if Mib not already
                       loaded - does nothing if Mib already loaded. will
                       parse directories and load modules according to
                       environment variables described in UCD documentations.
                       (see man mib_api, MIBDIRS, MIBS, MIBFILE(S), etc.)

&SNMP::addMibDirs(<dir>,...) - calls library add_mibdir for each directory
                       supplied. will cause directory(s) to be added to
                       internal list and made available for searching in
                       subsequent loadModules calls

&SNMP::addMibFiles(<file>,...) - calls library read_mib function. The file(s)
                      supplied will be read and all Mib module definitions
                      contained therein will be added to internal mib tree
                      structure

&SNMP::loadModules(<mod>,...) - calls library read_module function. The
                      module(s) supplied will be searched for in the
                      current mibdirs and and added to internal mib tree
                      structure. Passing special <mod>, 'ALL', will cause
                      all known modules to be loaded.

&SNMP::unloadModules(<mod>,...) - *Not Implemented*

&SNMP::translateObj(<var>) - will convert a text object tag to an OID and
                           vice-versa. iid suffix is retained numerically.
                           default behaviour when converting a numeric OID
                           to text form is to return leaf indentifier only
                           (e.g.,'sysDescr') but when $SNMP::use_long_names
                           is non-zero the whole identifier will be returned

&SNMP::getType(<var>) - return SNMP data type for given textual identifier
                       OBJECTID, OCTETSTR, INTEGER, NETADDR, IPADDR, COUNTER
                       GAUGE, TIMETICKS, OPAQUE, or undef

&SNMP::mapEnum(<var>) - converts integer value to enumertion tag defined
                       in Mib *Not Implemented*

Trouble Shooting:

If problems occur there are number areas to look at to narrow down the
possibilities.

The first step should be to test the UCD installation independent from
the Perl5/SNMP interface.

Try running the apps from the UCD distribution.

Ensure that your MIBs are installed and enviroment variables are set
appropriately (see man mib_api)

Be sure to remove old ucd-snmp installations

If the problem occurs during compilation/linking check that the snmp
library being linked is actually the UCD library (there have been name
conflicts with existing snmp libs).

Also check that the header files are correct and up to date.

Sometimes compiling the UCD snmp library with
'position-independent-code' enabled is required.

if you cannot resolve the problem you can email me at
[email protected] and/or [email protected].
and maybe I can help.

please give sufficient information to analyze the problem (OS type,
versions for OS/Perl/UCD/compiler, complete error output, etc.)

Acknowledments:

Many thanks to all those who supplied patches, suggestions and
feedback.

Wes Hardaker and the ucd-coders
Dave Perkins
Marcel Wiget
David Blackburn
John Stofell
Gary Hayward
Claire Harrison
Achim Bohnet
Doug Kingston
Jacques Vidrine
Perl5 Porters

Apologies to any/all who's patch/feature/request was not mentioned or
included - most likely it was lost when paying work intruded on my
fun. Please try again if you do not see a desired feature. This may
actually turn out to be a decent package with such excellent help and
the fact that I have more time to work on it than in the past.

bugs, comments, questions to [email protected]

------
History:

Bugs fixed and changes in 1.7

1) fixed seg fault on use of unknown/unparsed attribute in Varbind or
  passed to translateObj

2) fixed truncation of last char of attribute name in translateObj

3) handles variable args to setMib without complaint

4) added SNMP::getType to query data type of a given attribute and
  extended Varbind structure to return type wherever possible

5) added RemotePort to SNMP::Session initialation list to allow override
  of port 161

6) removed noisy announcement of mib parse success unless verbose is set

              *WARNING*  *this may break existing scripts*
7) changed return format for IpAddress and ObjID data types - these are
  now always returned as dotted decimal strings as opposed to the
  packed binary forms in 1.6
              *WARNING*  *this may break existing scripts*

8) Session now sets ErrorInd (e.g., $session->{ErrorInd}) where appropriate

9) Support for ucd-snmp-3.2 (and greater) style of Mib loading

10) Fully qualified attriubute names and numeric OIDs are now valid <obj>
  defintions.

11) Numeric OIDs can be used even if they have not been parsed in the
   current Mib - Mib loading is now optional

12) Support for Win32 perl

13) Updated docs and examples

14) Reworked/extended the test harness to use the perl t/* facility
   (thanks to [email protected])

15) fixed up error handling to be more consistent with library and more
   useful in general. Now returns both library API errors and snmp
   protocol error numbers and strings.

16) added per object and per type formatting of returned values - more
   control of value formatting with UseEnums and UseSprintValue

--
G. S. Marzot <[email protected]>   Network Management Development
Bay Networks Inc.                        (508)670-8888 x63990
--

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