The SNMP class

    (PHP 5 >= 5.4.0, PHP 7, PHP 8)

    Introduction

    Represents SNMP session.

    Class synopsis

    class SNMP {
    /* Constants */
    public const int VERSION_1;
    public const int VERSION_2c;
    public const int VERSION_2C;
    public const int VERSION_3;
    public const int ERRNO_NOERROR;
    public const int ERRNO_ANY;
    public const int ERRNO_GENERIC;
    public const int ERRNO_TIMEOUT;
    public const int ERRNO_ERROR_IN_REPLY;
    public const int ERRNO_OID_NOT_INCREASING;
    public const int ERRNO_OID_PARSING_ERROR;
    public const int ERRNO_MULTIPLE_SET_QUERIES;
    /* Properties */
    public readonly array $info;
    public ?int $max_oids;
    public int $valueretrieval;
    public bool $quick_print;
    public bool $enum_print;
    public int $oid_output_format;
    public bool $oid_increasing_check;
    public int $exceptions_enabled;
    /* Methods */
    public __construct(
        int $version,
        string $hostname,
        string $community,
        int $timeout = -1,
        int $retries = -1
    )
    public close(): bool
    public get(array|string $objectId, bool $preserveKeys = false): mixed
    public getErrno(): int
    public getError(): string
    public getnext(array|string $objectId): mixed
    public set(array|string $objectId, array|string $type, array|string $value): bool
    public setSecurity(
        string $securityLevel,
        string $authProtocol = "",
        string $authPassphrase = "",
        string $privacyProtocol = "",
        string $privacyPassphrase = "",
        string $contextName = "",
        string $contextEngineId = ""
    ): bool
    public walk(
        array|string $objectId,
        bool $suffixAsKey = false,
        int $maxRepetitions = -1,
        int $nonRepeaters = -1
    ): array|false
    }

    Properties

    max_oids

    Maximum OID per GET/SET/GETBULK request

    valueretrieval

    Controls the method how the SNMP values will be returned

    SNMP_VALUE_LIBRARYThe return values will be as returned by the Net-SNMP library.
    SNMP_VALUE_PLAINThe return values will be the plain value without the SNMP type information.
    SNMP_VALUE_OBJECT The return values will be objects with the properties "value" and "type", where the latter is one of the SNMP_OCTET_STR, SNMP_COUNTER etc. constants. The way "value" is returned is based on which one of SNMP_VALUE_LIBRARY, SNMP_VALUE_PLAIN is set
    quick_print

    Value of quick_print within the NET-SNMP library

    Sets the value of quick_print within the NET-SNMP library. When this is set (1), the SNMP library will return 'quick printed' values. This means that just the value will be printed. When quick_print is not enabled (default) the NET-SNMP library prints extra information including the type of the value (i.e. IpAddress or OID). Additionally, if quick_print is not enabled, the library prints additional hex values for all strings of three characters or less.

    enum_print

    Controls the way enum values are printed

    Parameter toggles if walk/get etc. should automatically lookup enum values in the MIB and return them together with their human readable string.

    oid_output_format

    Controls OID output format

    OID .1.3.6.1.2.1.1.3.0 representation for various oid_output_format values
    SNMP_OID_OUTPUT_FULL.iso.org.dod.internet.mgmt.mib-2.system.sysUpTime.sysUpTimeInstance
    SNMP_OID_OUTPUT_NUMERIC.1.3.6.1.2.1.1.3.0
    SNMP_OID_OUTPUT_MODULEDISMAN-EVENT-MIB::sysUpTimeInstance
    SNMP_OID_OUTPUT_SUFFIXsysUpTimeInstance
    SNMP_OID_OUTPUT_UCDsystem.sysUpTime.sysUpTimeInstance
    SNMP_OID_OUTPUT_NONEUndefined
    oid_increasing_check

    Controls disabling check for increasing OID while walking OID tree

    Some SNMP agents are known for returning OIDs out of order but can complete the walk anyway. Other agents return OIDs that are out of order and can cause SNMP::walk() to loop indefinitely until memory limit will be reached. PHP SNMP library by default performs OID increasing check and stops walking on OID tree when it detects possible loop with issuing warning about non-increasing OID faced. Set oid_increasing_check to false to disable this check.

    exceptions_enabled

    Controls which failures will raise SNMPException instead of warning. Use bitwise OR'ed SNMP::ERRNO_* constants. By default all SNMP exceptions are disabled.

    info

    Read-only property with remote agent configuration: hostname, port, default timeout, default retries count

    Predefined Constants

    SNMP Error Types

    SNMP::ERRNO_NOERROR

    No SNMP-specific error occurred.

    SNMP::ERRNO_GENERIC

    A generic SNMP error occurred.

    SNMP::ERRNO_TIMEOUT

    Request to SNMP agent timed out.

    SNMP::ERRNO_ERROR_IN_REPLY

    SNMP agent returned an error in reply.

    SNMP::ERRNO_OID_NOT_INCREASING

    SNMP agent faced OID cycling reporning non-increasing OID while executing (BULK)WALK command. This indicates bogus remote SNMP agent.

    SNMP::ERRNO_OID_PARSING_ERROR

    Library failed while parsing OID (and/or type for SET command). No queries has been made.

    SNMP::ERRNO_MULTIPLE_SET_QUERIES

    Library will use multiple queries for SET operation requested. That means that operation will be performed in a non-transaction manner and second or subsequent chunks may fail if a type or value failure will be faced.

    SNMP::ERRNO_ANY

    All SNMP::ERRNO_* codes bitwise OR'ed.

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    User Contributed Notes 2 notes

    up
    0
    swannie at swannie dot net
    3 years ago
    Hopefully this helps someone else out because this was driving be bonkers for a good two hours. It looks like valueretrieval and enum_print work together in a way that I wasn't expecting, and after re-reading may be by design but I'm not sure. If you can't get enums to print, this might be why.

    <?php
    $snmp     = new SNMP(SNMP::VERSION_2C,'192.168.1.9','test');
    $snmp->oid_output_format = SNMP_OID_OUTPUT_SUFFIX;
    $snmp->valueretrieval = SNMP_VALUE_PLAIN;
    $snmp->enum_print = 0;
    echo     $snmp->get('IF-MIB::ifOperStatus.10110') . "\n";
    $snmp->enum_print = 1;
    echo     $snmp->get('IF-MIB::ifOperStatus.10110') . "\n";
    $snmp->quick_print = 1;
    echo     $snmp->get('IF-MIB::ifOperStatus.10110') . "\n";
    $snmp->valueretrieval = SNMP_VALUE_LIBRARY;
    echo     $snmp->get('IF-MIB::ifOperStatus.10110') . "\n";
    $snmp->enum_print = 0;
    echo     $snmp->get('IF-MIB::ifOperStatus.10110') . "\n";
    ?>

    Output:
    1
    1
    1
    1
    up
    up
    -1
    madjev1990 at gmail dot com
    8 years ago
    Part of my diploma thesis was to create web interface to command device via SNMP. So I create my own level of abstraction over SNMP class:

    <?php

    /**
    * Snmp library which add one level of abstraction to snmp native library.
    * It adds functionality to work with module PicoIP.With this library you can:
    * 1.Activate/deactive defined pin;
    * 2.Get status of all pins.
    *
    * When make an instance you should pass to the constructor key word which will
    * make the library create an object with necessary properetis and access permissions.
    *
    * Private properties set some of configurations:
    * Host is IP address of the divece which we will command.
    * Two passwords are set for reading and writing.
    * Version of snmp protocol that we will use is version 1.
    *
    * @author Radoslav Madjev
    * @year 2016
    * @version 1.0 beta
    *
    *
    */
    class snmp_lib {

    private     $snmpInstance;
    private     $VERSION = SNMP::VERSION_1;
    private     $HOST = '192.168.0.150';
    private     $passwordRead = '000000000000';
    private     $passwordWrite = 'private';
    private     $releys = array(1 => '1.3.6.1.4.1.19865.1.2.1.1.0',
    2 => '1.3.6.1.4.1.19865.1.2.1.2.0');
    private     $allPorts = array('3' => '1.3.6.1.4.1.19865.1.2.1.33.0',
    '5' => '1.3.6.1.4.1.19865.1.2.2.33.0');

    /**
    * Create instance of SNMP native class, based on actions that we will
    * perform.
    *
    * @param string $action
    */
    public function __construct($action) {
    if (    in_array($action, array('read', 'write'))) {
    if (    strcmp($action, 'read') === 0) {
    $this->_read();
    } else {
    $this->_write();
    }
    }
    }

    /**
    * Create instance with reading permissions.
    */
    private function _read() {
    $this->snmpInstance = new SNMP($this->VERSION, $this->HOST, $this->passwordRead);
    }

    /**
    * Create instance with writing permissions.
    */
    private function _write() {
    $this->snmpInstance = new SNMP($this->VERSION, $this->HOST, $this->passwordWrite);
    }

    /**
    * Close snmp session.
    *
    * @return boolean
    */
    public function closeSession() {
    return     $this->snmpInstance->close();
    }

    /**
    * Set integer 1 as value of defined pin.
    */
    public function activate($relay) {
    $this->snmpInstance->set($this->releys[$relay], 'i', '1');
    }

    /**
    * Set integer 0 as value of defined pin.
    */
    public function deactivate($relay) {
    $this->snmpInstance->set($this->releys[$relay], 'i', '0');
    }

    /**
    * Get pin status of all ports of the module.
    *
    * @return array
    */
    public function getAllPortsStatus() {
    $allPins = array();
    foreach (    $this->allPorts as $number => $port) {
    //get active pins as 8-bit integer of defined port
    $getbits = $this->snmpInstance->get($port);
    $bits = str_replace('INTEGER: ', '', $getbits);
    //get pins status
    $pinsStatus = $this->_getActivePins($bits);
    $allPins[$number] = $pinsStatus;
    }

    return     $allPins;
    }

    /**
    * Make bitwise operation which will determine,
    * which are active pins.
    *
    * @param int $bits
    * @return array
    */
    private function _getActivePins($bits) {

    $bitMapping = array(
    1 => 1,
    2 => 2,
    3 => 4,
    4 => 8,
    5 => 16,
    6 => 32,
    7 => 64,
    8 => 128
    );

    $pinsStatus = array();

    foreach (    $bitMapping as $int => $bit) {
    if ((    $bits & $bit) == $bit) {
    $pinsStatus[$int] = true;
    continue;
    }
    $pinsStatus[$int] = false;
    }

    return     $pinsStatus;
    }

    }

    ?>

    I have one module that receive SNMP request and send a command to relays. Also these are example scripts that use this lib:
    Turn on script:
    <?php
    require_once 'snmp_lib.php';

    $snmp = new snmp_lib('write');
    $snmp->activate($getRelayNumber);
    $snmp->closeSession();
    ?>

    Turn off script:
    <?php
    require_once 'snmp_lib.php';

    $snmp = new snmp_lib('write');
    $snmp->deactivate($getRelayNumber);
    $snmp->closeSession();
    ?>

    Script that get all ports status:
    <?php
    require_once 'snmp_lib.php';

    $snmp = new snmp_lib('read');
    $getActive = $snmp->getAllPortsStatus();
    ?>
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