Perl5 SNMP Extension Module v1.8 for the UCD SNMP Library G.S. Marzot (gmarzot@baynetworks.com) Contents: Introduction: Availability: Supported Platforms: Release Notes: Installation: Operational Description: Trouble Shooting: Acknowledments: History: Introduction: This is a Perl5 extension module which provides a full featured SNMP client side API. The SNMP module internals rely on the UCD SNMP client library toolkit. The UCD SNMP library was originally based on version 2.1.2.1 of the CMU SNMP library but has incorporated many bugfixes and enhancements. For information on the UCD SNMP library see the documentation provided with the UCD SNMP distribution or the ucd-snmp project web page: http://www.ece.ucdavis.edu/ucd-snmp (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 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.wellfleet.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 Release Notes: version 1.8 is intended to compile w/ ucd-snmp-3.5 (1.8a1 was targetted at ucd-snmp-3.4). Compatibility with later versions of ucd-snmp is not guaranteed due to the dynamic nature of free software development :). As of 1.8a2, 'make test' will fail session test 9 when tested with the ucd-snmp agent due to a bug in the agent in which 'set's to read-only attributes appear to succeed. This 'make test' failure can be safely ignored. Installation: build and install ucd-snmp-3.5 note: you should ensure that any previous ucd-snmp or cmu snmp installation is located so that the wrong libsnmp or headers are not used by mistake). perl Makefile.PL make make test make install note: 'make test' requires that an agent is running to which you have read/write access. For the ucd-snmp snmpd this may involve setting up the snmpd.conf file with read-write access for 'private' Operational Description: The basic operations offered by the SNMP module are provided 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). 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 '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) VarFormats - default 'undef', used by 'fget[next]', holds an hash reference of output value formatters, (e.g., { => , ... }, must match the and format used in the get operation. A special , '*', may be used to apply all 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., { => , ... }, the supplied sub is called to translate the value to a new format, unless a VarFormat mathces first (e.g., $session->{TypeFormats}{INTEGER} = \&mapEnum(); although this can be done more efficiently by enabling $SNMP::use_enums or session creation param 'UseEnums') UseLongNames - defaults to the value of SNMP::use_long_names at time of session creation. set to non-zero to have 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 of value formats in 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() - 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()- Updates the SNMP::Session object with the values fields passed in as a hash list (similar to new()) (WARNING! not fully implemented) get([,]) - do SNMP GET, multiple formats accepted, for syncronous operation will be updated with value(s) and type(s) and will return retrieved value(s). If supplied method will operate asyncronously fget([,]) - do SNMP GET like 'get' and format the values according the handlers specified in $sess->{VarFormats} and $sess->{TypeFormats} getnext([,]) - do SNMP GETNEXT, multiple formats accepted, returns retrieved value(s), passed as arguments are updated to indicate next lexicographical ,,, and NOTE: simple string ,(e.g., 'sysDescr.0') form is not updated. If supplied method will operate asyncronously fgetnext([,]) - do SNMP GETNEXT like getnext and format the values according the handlers specified in $sess->{VarFormats} and $sess->{TypeFormats} set([,]) - do SNMP SET, multiple formats accepted, the value field in all 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 description section), returns snmp_errno. If supplied method will operate asyncronously getbulk(, , ) - * Not Implemented * SNMP::TrapSession - supports all aplicable fields from SNMP::Session (see above) methods: new() - Constructs a new SNMP::TrapSession object. The fields are passed to the contructor as a hash list (e.g., $trapsess = new SNMP::Session(DestHost => 'foo', Community => 'private');), returns an object reference or undef in case of error. trap(enterprise, agent, generic, specific, uptime, ) $sess->trap(enterprise=>'.1.3.6.1.4.1.2021', # or 'ucdavis' [default] agent => '127.0.0.1', # 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 or v2 format trap(srcParty, dstParty, oid, uptime, ) - * Not Implemented * $sess->trap(srcParty => party1, dstParty => party2, oid => 'snmpRisingAlarm', uptime => 1234, [[ifIndex, 1, 1],[sysLocation, 0, "here"]]); # optional vars # always last Acceptable variable formats: 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., [, , ...]) SNMP::Varbind: - represents a single MIB object to get or set, implemented as a blessed reference to a 4 element array; [, , , ]. - 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') - 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 may have a variety of formats as determined by session and package settings. However for set operations the 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, - 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 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 fileds must be supplied simple string - light weight form of used to 'set' or 'get' a single attribute without constructing an SNMP::Varbind. stored in a perl scalar, has the form '.', (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: 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 the SNMP::VarList. SNMP package variables and functions: $SNMP::VERSION - the current version specifier (e.g., 1.8) $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', 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 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::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', 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) $SNMP::dump_packet - default '0', set [non-]zero to independently set snmp_set_dump_packet() %SNMP::MIB - a tied hash to access parsed MIB information. After the MIB has been loaded this hash allows access to to the parsed in MIB meta-data. The hash returns references to SNMP::MIB::NODE objects which represent a single MIB attribute. The nodes can be fetched with multiple 'key' formats - the leaf name (e.g.,sysDescr) or fully/partially qualified name (e.g., system.sysDescr) or fully qualified numeric OID. The returned node object supports the following fields: objectID - dotted decimal fully qualified OID label - leaf textual identifier (e.g., 'sysDescr') subID - leaf numeric OID component of objectID (e.g., '1') moduleID - textual identifier for module (e.g., 'RFC1213-MIB') parent - parent node children - array reference of children nodes nextNode - next lexico node (BUG!does not return in lexico order) type - returns simple type (see getType for values) access - returns ACCESS (ReadOnly, ReadWrite, WriteOnly, NoAccess, Notify, Create) status - returns STATUS (Mandatory, Optional, Obsolete, Deprecated) syntax - returns 'textualConvention' if defined else 'type' textualConvention - returns TEXTUAL-CONVENTION units - returns UNITS hint - returns HINT enums - returns hash ref {tag => num, ...} description - returns DESCRIPTION ($SNMP::save_descriptions must be set prior to MIB initialization/parsing) &SNMP::setMib() - 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 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(,...) - 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(,...) - 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(,...) - 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 , 'ALL', will cause all known modules to be loaded. &SNMP::unloadModules(,...) - *Not Implemented* &SNMP::translateObj([,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 indentifier only (e.g.,'sysDescr') but when $SNMP::use_long_names is non-zero or a non-zero second arg is supplied will return longer textual identifier. 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() - return SNMP data type for given textual identifier OBJECTID, OCTETSTR, INTEGER, NETADDR, IPADDR, COUNTER GAUGE, TIMETICKS, OPAQUE, or undef &SNMP::mapEnum() - 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); &SNMP::MainLoop() - 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. This function enters an infinite loop so program must be exited in a callback or externally interupted. 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 UCD installation independently from the Perl5/SNMP interface. Try running the apps from the UCD distribution. Make sure your agent 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 ucd-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 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 (HPUX specifically). if you cannot resolve the problem you can email me at gmarzot@baynetworks.com and/or ucd-snmp-coders@ece.ucdavis.edu. 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 Carl Jacobsen Wayne Marquette Scott Schumate 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 gmarzot@baynetworks.com ------ History: Bugs fixed and changes in 1.8 1) added async API (async api should be considered late alpha - potential changes are most likely in the event loop integration area - would like to integrate with Event.pm - also mechanism for indicating timeout to callback is required) 2) added trap generation API (implemented v1 traps only for now) 3) added and exported non-OO utility API (snmp_get, snmp_set, etc.) 4) added $SNMP::debugging to dynmically control libsnmp debugging output 5) added $SNMP::save_descriptions to control libsnmp parsing/saving of MIB descriptions 6) added $SNMP::dump_packet to control libsnmp packet dumping 7) implemented the SNMP::mapEnum function (thanks to Wayne Marquette) 8) officially added(documented) tied %SNMP::MIB hash to allow access to parsed MIB meta-data (new support for textualConvention and syntax) 9) fixed bug related to AUTOLOAD recursion 10) fixed bug with SNMP::use_enums so 'set' (and trap) should now accept enums as input values 11) fixed bug with fget[next] - formatted values are supplied as return values as well as within args passed 12) fixed Makefile to link with -kstat on solaris 13) fixed bug when handling noSuchName returns for getnext calls with varbinds w/ no iid supplied (__get_label_iid should not use the FAIL_ON_NULL_IID flag) 14) fixed bug with uninitialized sprintval_flag 15) fixed bug when no val is passed to SNMP::Session::set - now will not core or complain about uninitialized data 16) fixed bug with __translate_appl_type in case of NULL or empty string 17) eliminated the use of strtoul for portability - use sscanf(,"%lu",) 18) getType() supports all tag formats now 19) fixed bug when setting values of type OBJID (thanks Scott Schumate) 20) *WARNING* RetryNoSuch in session creation had a bug which prevented it from being disbaled. It now defaults to being disabled - this may break code *WARNING* 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 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 jfs@fluent.com) 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