readme

开发snmp的开发包有两个开放的SNMP开发库

                               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:
       \&subname
       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 package variables and functions:

    $SNMP::VERSION       - the current version specifier (e.g., 3.1.0)

    $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 Net-SNMP env. variables
   			(see man mib_api)

    $SNMP::verbose       - 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)

    $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::use_numeric   - default '0', set to non-zero to return tags as numeric
                           OID's, instead of translating them.  Also setting
                           $SNMP::use_long_names to non-zero is highly recommended.

    $SNMP::best_guess    - 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)

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

    $SNMP::debugging     - default '0', controls 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)

    $SNMP::dump_packet   - default '0', set [non-]zero to independently set
                           snmp_set_dump_packet()

    %SNMP::MIB           - 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:

           objectID      - dotted decimal fully qualified OID
           label         - leaf textual identifier (e.g., 'sysDescr')
           subID         - leaf numeric OID component of objectID (e.g., '1')
           moduleID      - textual identifier for module (e.g., 'RFC1213-MIB')
           parent        - parent node
           children      - array reference of children nodes
           nextNode      - next lexico node (BUG!does not return in lexico order)
           type          - returns application type (see getType for values)
           access        - returns ACCESS (ReadOnly, ReadWrite, WriteOnly,
                           NoAccess, Notify, Create)
           status        - returns STATUS (Mandatory, Optional, Obsolete,
                           Deprecated, Current)
           syntax        - returns 'textualConvention' if defined else 'type'
           textualConvention - returns TEXTUAL-CONVENTION
           units         - returns UNITS
           hint          - returns HINT
           enums         - returns hash ref {tag => num, ...}
           ranges        - returns array ref of hash ref [{low=>num, high=>num}]
           defaultValue  - returns default value
           description   - returns DESCRIPTION ($SNMP::save_descriptions must
                           be set prior to MIB initialization/parsing)


    &SNMP::setMib(<file>) - allows dynamic parsing of the mib and explicit
                            specification of mib file independent of environment
                            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).

    &SNMP::initMib()     - calls library netsnmp_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.)

    &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>[,arg,[arg]]) - 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 
                          failure.

    &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 enumeration 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);

    &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 supplied this function enters an infinite loop
                        so program must be exited in a callback or externally
                        interrupted. If <timeout

    &SNMP::finish()
   		   - 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.

   Exported SNMP utility functions
   &snmp_get() - takes args of SNMP::Session::new followed by those of
                 SNMP::Session::get

   &snmp_getnext() - takes args of SNMP::Session::new followed by those of
                     SNMP::Session::getnext

   &snmp_set() - takes args of SNMP::Session::new followed by those of
                 SNMP::Session::set

   &snmp_trap() - takes args of SNMP::TrapSession::new followed by those of
                  SNMP::TrapSession::trap

   Note: utility functions do not support async operation yet.

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 environment variables are set
   appropriately (see man mib_api)

   Be sure to ensure headers and libraries from old CMU installations are
   not being used by mistake (see -NET-SNMP-PATH).

   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 email [e-mail].

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

Acknowledgments:

   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.

Copyright:

     [See the COPYING file for the copyright license of Net-SNMP]

     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
     itself.

     Copyright (c) 2003-2006 SPARTA, Inc.  All Rights Reserved.  This
     program is free software; you can redistribute it and/or modify
     it under the same terms as Perl itself.