Provided by: libsnmp-dev_5.4.3~dfsg-2.4ubuntu1_amd64 bug


       SNMP - The Perl5 'SNMP' Extension Module for the Net-SNMP SNMP package.


        use SNMP;
        $sess = new SNMP::Session(DestHost => localhost, Community => public);
        $val = $sess->get('sysDescr.0');
        $vars = new SNMP::VarList([sysDescr,0], [sysContact,0], [sysLocation,0]);
        @vals = $sess->get($vars);
        $vb = new SNMP::Varbind();
        do {
           $val = $sess->getnext($vb);
           print "@{$vb}\n";
        } until ($sess->{ErrorNum});
        $SNMP::save_descriptions = 1;
        SNMP::initMib(); # assuming mib is not already loaded
        print "$SNMP::MIB{sysDescr}{description}\n";


       Note: The perl SNMP 5.0 module which comes with net-snmp 5.0 and higher is different than
       previous versions in a number of ways.  Most importantly, it behaves like a proper net-
       snmp application and calls init_snmp properly, which means it will read configuration
       files and use those defaults where appropriate automatically parse MIB files, etc.  This
       will likely affect your perl applications if you have, for instance, default values set up
       in your snmp.conf file (as the perl module will now make use of those defaults).  The
       docmuentation, however, has sadly not been updated yet (aside from this note), nor is the
       read_config default usage implementation fully complete.

       The basic operations of the SNMP protocol are provided by this module through an object
       oriented interface for modularity and ease of use.  The primary class is SNMP::Session
       which encapsulates the persistent aspects of a connection between the management
       application and the managed agent. Internally the class is implemented as a blessed hash
       reference. This class supplies 'get', 'getnext', 'set', 'fget', and 'fgetnext' method
       calls. The methods take a variety of input argument formats and support both syncronous
       and asyncronous operation through a polymorphic API (i.e., method behaviour varies
       dependent on args passed - see below).


       $sess = new SNMP::Session(DestHost => 'host', ...)

       The following arguments may be passed to new as a hash.

           default 'localhost', hostname or ip addr of SNMP agent

           default 'public', SNMP community string (used for both R/W)

           default taken from library configuration - probably 3 [1, 2 (same as 2c), 2c, 3]

           default '161', allow remote UDP port to be overriden

           default '1000000', micro-seconds before retry

           default '5', retries before failure

           default '0', if enabled NOSUCH errors in 'get' pdus will be repaired, removing the
           varbind in error, and resent - undef will be returned for all NOSUCH varbinds, when
           set to '0' this feature is disabled and the entire get request will fail on any NOSUCH
           error (applies to v1 only)

           default 'initial', security name (v3)

           default 'noAuthNoPriv', security level [noAuthNoPriv, authNoPriv, authPriv] (v3)

           default <none>, security engineID, will be probed if not supplied (v3)

           default <SecEngineId>, context engineID, will be probed if not supplied (v3)

           default '', context name (v3)

           default 'MD5', authentication protocol [MD5, SHA] (v3)

           default <none>, authentication passphrase

           default 'DES', privacy protocol [DES, AES] (v3)

           default <none>, privacy passphrase (v3)

           Directly specified SNMPv3 USM user keys (used if you want to specify the keys instead
           of deriving them from a password as above).

           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

           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.,
           $sess->{TypeFormats}{INTEGER} = \&mapEnum(); although this can be done more
           efficiently by enabling $SNMP::use_enums or session creation param 'UseEnums')

           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)

           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 snprint_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 of value formats in <vars>
           description section)

           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

           defaults to the value of SNMP::use_numeric at time of session creation. set to non-
           zero to have <tags> for get methods returned as numeric OID's rather than
           descriptions.  UseLongNames will be set so that the full OID is returned to the

           defaults to the value of SNMP::best_guess at time of session creation. this setting
           controls how <tags> are parsed.  setting to 0 causes a regular lookup.  setting to 1
           causes a regular expression match (defined as -Ib in snmpcmd) and setting to 2 causes
           a random access lookup (defined as -IR in snmpcmd).

           defaults to the value of SNMP::non_increasing at time of session creation. this
           setting controls if a non-increasing OID during bulkwalk will causes an error. setting
           to 0 causes the default behaviour (which may, in very badly performing agents, result
           in a never-ending loop).  setting to 1 causes an error (OID not increasing) when this
           error occur.

           read-only, holds the error message assoc. w/ last request

           read-only, holds the snmp_err or staus of last request

           read-only, holds the snmp_err_index when appropriate

       Private variables:

           internal field used to hold the translated DestHost field

           internal field used to cache a created session structure

   SNMP::Session methods
           Updates the SNMP::Session object with the values fields passed in as a hash list
           (similar to new(<fields>)) (WARNING! not fully implemented)

       $sess->get(<vars> [,<callback>])
           do SNMP GET, multiple <vars> formats accepted.  for syncronous operation <vars> will
           be updated with value(s) and type(s) and will also return retrieved value(s). If
           <callback> supplied method will operate asyncronously

       $sess->fget(<vars> [,<callback>])
           do SNMP GET like 'get' and format the values according the handlers specified in
           $sess->{VarFormats} and $sess->{TypeFormats}

       $sess->getnext(<vars> [,<callback>])
           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. If <callback>
           supplied method will operate asyncronously

       $sess->fgetnext(<vars> [,<callback>])
           do SNMP GETNEXT like getnext and format the values according the handlers specified in
           $sess->{VarFormats} and $sess->{TypeFormats}

       $sess->set(<vars> [,<callback>])
           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. If <callback> supplied method will operate

       $sess->getbulk(<non-repeaters>, <max-repeaters>, <vars>)
           do an SNMP GETBULK, from the list of Varbinds, the single next lexico instance is
           fetched for the first n Varbinds as defined by <non-repeaters>. For remaining
           Varbinds, the m lexico instances are retrieved each of the remaining Varbinds, where m
           is <max-repeaters>.

       $sess->bulkwalk(<non-repeaters>, <max-repeaters>, <vars> [,<callback>])
           Do a "bulkwalk" of the list of Varbinds.  This is done by sending a GETBULK request
           (see getbulk() above) for the Varbinds.  For each requested variable, the response is
           examined to see if the next lexico instance has left the requested sub-tree.  Any
           further instances returned for this variable are ignored, and the walk for that sub-
           tree is considered complete.

           If any sub-trees were not completed when the end of the responses is reached, another
           request is composed, consisting of the remaining variables.  This process is repeated
           until all sub-trees have been completed, or too many packets have been exchanged (to
           avoid loops).

           The bulkwalk() method returns an array containing an array of Varbinds, one for each
           requested variable, in the order of the variable requests.  Upon error, bulkwalk()
           returns undef and sets $sess->ErrorStr and $sess->ErrorNum.  If a callback is
           supplied, bulkwalk() returns the SNMP request id, and returns immediately.  The
           callback will be called with the supplied argument list and the returned variables

           Note: Because the client must "discover" that the tree is complete by comparing the
           returned variables with those that were requested, there is a potential "gotcha" when
           using the max-repeaters value.  Consider the following code to print a list of
           interfaces and byte counts:

               $numInts = $sess->get('ifNumber.0');
               ($desc, $in, $out) = $sess->bulkwalk(0, $numInts,
                             [['ifDescr'], ['ifInOctets'], ['ifOutOctets']]);

               for $i (0..($numInts - 1)) {
                   printf "Interface %4s: %s inOctets, %s outOctets\n",
                             $$desc[$i]->val, $$in[$i]->val, $$out[$i]->val;

           This code will produce *two* requests to the agent -- the first to get the interface
           values, and the second to discover that all the information was in the first packet.
           To get around this, use '$numInts + 1' for the max_repeaters value.  This asks the
           agent to include one additional (unrelated) variable that signals the end of the sub-
           tree, allowing bulkwalk() to determine that the request is complete.

       $results = $sess->gettable(<TABLE OID>, <OPTIONgt)
           This will retrieve an entire table of data and return a hash reference to that data.
           The returned hash reference will have indexes of the OID suffixes for the index data
           as the key.  The value for each entry will be another hash containing the data for a
           given row.  The keys to that hash will be the column names, and the values will be the



             use SNMP;
             use Data::Dumper;

             my $s = new SNMP::Session(DestHost => 'localhost');

             print Dumper($s->gettable('ifTable'));

           On my machine produces:

             $VAR1 = {
                       '6' => {
                                'ifMtu' => '1500',
                                'ifPhysAddress' => 'PV',
                                # ...
                                'ifInUnknownProtos' => '0'
                       '4' => {
                                'ifMtu' => '1480',
                                'ifPhysAddress' => '',
                                # ...
                                'ifInUnknownProtos' => '0'
                       # ...

           By default, it will try to do as optimized retrieval as possible.  It'll request
           multiple columns at once, and use GETBULK if possible.  A few options may be specified
           by passing in an OPTIONS hash containing various parameters:

           noindexes => 1
               Instructs the code not to parse the indexes and place the results in the second
               hash.  If you don't need the index data, this will be faster.

           columns => [ colname1, ... ]
               This specifies which columns to collect.  By default, it will try to collect all
               the columns defined in the MIB table.

           repeat => COUNT
               Specifies a GETBULK repeat COUNT.  IE, it will request this many varbinds back per
               column when using the GETBULK operation.  Shortening this will mean smaller
               packets which may help going through some systems.  By default, this value is
               calculated and attepmts to guess at what will fit all the results into 1000 bytes.
               This calculation is fairly safe, hopefully, but you can either raise or lower the
               number using this option if desired.  In lossy networks, you want to make sure
               that the packets don't get fragmented and lowering this value is one way to help

           nogetbulk => 1
               Force the use of GETNEXT rather than GETBULK.  (always true for SNMPv1, as it
               doesn't have GETBULK anyway).  Some agents are great implementers of GETBULK and
               this allows you to force the use of GETNEXT oprations instead.

           callback => \&subroutine
           callback => [\&subroutine, optarg1, optarg2, ...]
               If a callback is specified, gettable will return quickly without returning
               results.  When the results are finally retrieved the callback subroutine will be
               called (see the other sections defining callback behaviour and how to make use of
               SNMP::MainLoop which is required fro this to work).  An additional argument of the
               normal hash result will be added to the callback subroutine arguments.

               Note 1: internally, the gettable function uses it's own callbacks which are passed
               to getnext/getbulk as appropriate.

               Note 2: callback support is only available in the SNMP module version 5.04 and
               above.  To test for this in code intending to support both versions prior to 5.04
               and and 5.04 and up, the following should work:

                 if ($response = $sess->gettable('ifTable', callback => \&my_sub)) {
                     # got a response, gettable doesn't support callback
                     $no_mainloop = 1;

               Deciding on whether to use SNMP::MainLoop is left as an excersize to the reader
               since it depends on whether your code uses other callbacks as well.


       $sess = new SNMP::Session(DestHost => 'host', ...)

       supports all applicable fields from SNMP::Session (see above)

   SNMP::TrapSession methods
       $sess->trap(enterprise, agent, generic, specific, uptime, <vars>)
               $sess->trap(enterprise=>'.', # or 'ucdavis' [default]
                           agent => '', # or 'localhost',[dflt 1st intf on host]
                           generic => specific,  # can be omitted if 'specific' supplied
                           specific => 5,        # can be omitted if 'generic' supplied
                           uptime => 1234,       # dflt to localhost uptime (0 on win32)
                           [[ifIndex, 1, 1],[sysLocation, 0, "here"]]); # optional vars
                                                                        # always last

       trap(oid, uptime, <vars>) - v2 format
               $sess->trap(oid => 'snmpRisingAlarm',
                           uptime => 1234,
                           [[ifIndex, 1, 1],[sysLocation, 0, "here"]]); # optional vars
                                                                        # always last

Acceptable variable formats:

       <vars> may be one of the following forms:

           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>, ...])

           represents a single MIB object to get or set, implemented as a blessed reference to a
           4 element array; [<obj>, <iid>, <val>, <type>].

               one of the following forms:

               1)  leaf identifier (e.g., 'sysDescr') assumed to be unique for practical purposes

               2)  fully qualified identifier (e.g.,

               3)  fully qualified, dotted-decimal, numeric OID (e.g., '.')

               the dotted-decimal, instance identifier. for scalar MIB objects use '0'

               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:

                   dotted-decimal (e.g., .

                   perl scalar containing octets

                   decimal signed integer (or enum)



                   decimal unsigned integer

                   decimal unsigned integer

                   decimal unsigned integer

                   decimal unsigned integer

                   decimal unsigned integer

                   perl scalar containing octets

                   perl scalar containing nothing

               SNMP data type (see list above), this field is populated by 'get' and 'getnext'
               operations. In some cases the programmer needs to populate this field when passing
               to a 'set' operation. this field need not be supplied when the 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> field 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.

Acceptable callback formats

       <callback> may be one of the following forms:

       without arguments
           sub { ... }
       or with arguments
           [ \&subname, $arg1, ... ]
           [ sub { ... }, $arg1, ... ]
           [ "method", $obj, $arg1, ... ]

       callback will be called when response is received or timeout occurs. the last argument
       passed to callback will be a SNMP::VarList reference. In case of timeout the last argument
       will be undef.

       &SNMP::MainLoop([<timeout>, [<callback>]])
           to be used with async SNMP::Session calls. MainLoop must be called after initial async
           calls so return packets from the agent will not be processed.  If no args suplied this
           function enters an infinite loop so program must be exited in a callback or externally
           interupted. If <timeout(sic)

           This function, when called from an SNMP::MainLoop() callback function, will cause the
           current SNMP::MainLoop() to return after the callback is completed.  finish() can be
           used to terminate an otherwise-infinite MainLoop.  A new MainLoop() instance can then
           be started to handle further requests.

SNMP package variables and functions

           the current version specifier (e.g., 3.1.0)

           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 Net-SNMP env. variables (see man mib_api)

           default '0', controls warning/info output of SNMP module, 0 => no output, 1 => enables
           warning/info output from SNMP module itself (is also controlled by SNMP::debugging -
           see below)

           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)

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

           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)

           default to '0',set to non-zero to have <tags> for 'get' methods returned as numeric
           OID's rather than descriptions.  UseLongNames will be set so that the entire OID will
           be returned.  Set on a per-session basis (see UseNumeric).

           default '0'.  This setting controls how <tags> are parsed.  Setting to 0 causes a
           regular lookup.  Setting to 1 causes a regular expression match (defined as -Ib in
           snmpcmd) and setting to 2 causes a random access lookup (defined as -IR in snmpcmd).
           Can also be set on a per session basis (see BestGuess)

           default '0',set non-zero to have mib parser save attribute descriptions. must be set
           prior to mib initialization

           default '0', controlls debugging output level within SNMP module and libsnmp

           1.  enables 'SNMP::verbose' (see above)

           2.  level 1 plus snmp_set_do_debugging(1)

           3.  level 2 plus snmp_set_dump_packet(1)

           default '0', set [non-]zero to independently set snmp_set_dump_packet()


       a tied hash to access parsed MIB information. After the MIB has been loaded this hash
       allows access to to the parsed in MIB meta-data(the structure of the MIB (i.e., schema)).
       The hash returns blessed references to SNMP::MIB::NODE objects which represent a single
       MIB attribute. The nodes can be fetched with multiple 'key' formats - the leaf name
       (e.g.,sysDescr) or fully/partially qualified name (e.g., system.sysDescr) or fully
       qualified numeric OID. The returned node object supports the following fields:

           dotted decimal fully qualified OID

           leaf textual identifier (e.g., 'sysDescr')

           leaf numeric OID component of objectID (e.g., '1')

           textual identifier for module (e.g., 'RFC1213-MIB')

           parent node

           array reference of children nodes

           next lexico node (BUG!does not return in lexico order)

           returns application type (see getType for values)

           returns ACCESS (ReadOnly, ReadWrite, WriteOnly, NoAccess, Notify, Create)

           returns STATUS (Mandatory, Optional, Obsolete, Deprecated)

           returns 'textualConvention' if defined else 'type'

           returns TEXTUAL-CONVENTION

           returns the TEXTUAL-CONVENTION's DESCRIPTION field.

           returns UNITS

           returns HINT

           returns hash ref {tag => num, ...}

           returns array ref of hash ref [{low => num, high => num}, ...]

           returns DESCRIPTION ($SNMP::save_descriptions must be set prior to MIB

           returns the REFERENCE clause

MIB Functions

           allows dynamic 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 Net-SNMP 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).

           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 Net-SNMP documentations.  (see man mib_api, MIBDIRS, MIBS,
           MIBFILE(S), etc.)

           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 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

           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.

           *Not Implemented*

           will convert a text obj tag to an OID and vice-versa.  Any iid suffix is retained
           numerically.  Default behaviour when converting a numeric OID to text form is to
           return leaf identifier only (e.g.,'sysDescr') but when $SNMP::use_long_names is non-
           zero or a non-zero second arg is supplied it will return a longer textual identifier.
           An optional third argument of non-zero will cause the module name to be prepended to
           the text name (e.g.  'SNMPv2-MIB::sysDescr').  When converting a text obj, the
           $SNMP::best_guess option is used.  If no Mib is loaded when called and
           $SNMP::auto_init_mib is enabled then the Mib will be loaded. Will return 'undef' upon

           return SNMP data type for given textual identifier OBJECTID, OCTETSTR, INTEGER,

           converts integer value to enumertion tag defined in Mib or converts tag to integer
           depending on input. the function will return the corresponding integer value *or* tag
           for a given MIB attribute and value. The function will sense which direction to
           perform the conversion. Various arg formats are supported

           $val = SNMP::mapEnum($varbind);
               where $varbind is SNMP::Varbind or equiv.  note: $varbind will be updated

           $val = SNMP::mapEnum('ipForwarding', 'forwarding');
           $val = SNMP::mapEnum('ipForwarding', 1);

Exported SNMP utility functions

       Note: utility functions do not support async operation yet.

           takes args of SNMP::Session::new followed by those of SNMP::Session::get

           takes args of SNMP::Session::new followed by those of SNMP::Session::getnext

           takes args of SNMP::Session::new followed by those of SNMP::Session::set

           takes args of SNMP::TrapSession::new followed by those of SNMP::TrapSession::trap

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 Net-SNMP installation independently from the Perl5
       SNMP interface.

       Try running the apps from the Net-SNMP distribution.

       Make sure your agent (snmpd) is running and properly configured with read-write access for
       the community you are using.

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

       Be sure to remove old net-snmp installations and ensure headers and libraries from old CMU
       installations are not being used by mistake.

       If the problem occurs during compilation/linking check that the snmp library being linked
       is actually the Net-SNMP 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 Net-SNMP library with 'position-independent-code' enabled is
       required (HPUX specifically).

       If you cannot resolve the problem you can post to comp.lang.perl.modules or

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


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

        Joe Marzot (the original author)
        Wes Hardaker and the net-snmp-coders
        Dave Perkins
        Marcel Wiget
        David Blackburn
        John Stofell
        Gary Hayward
        Claire Harrison
        Achim Bohnet
        Doug Kingston
        Jacques Vidrine
        Carl Jacobsen
        Wayne Marquette
        Scott Schumate
        Michael Slifcak
        Srivathsan Srinivasagopalan
        Bill Fenner
        Jef Peeraer
        Daniel Hagerty
        Karl "Rat" Schilke and Electric Lightwave, Inc.
        Perl5 Porters
        Alex Burger

       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


            Copyright (c) 1995-2000 G. S. Marzot. All rights reserved.
            This program is free software; you can redistribute it and/or
            modify it under the same terms as Perl itself.

            Copyright (c) 2001-2002 Networks Associates Technology, Inc.  All
            Rights Reserved.  This program is free software; you can
            redistribute it and/or modify it under the same terms as Perl