snmpwalk

(PHP 4, PHP 5, PHP 7, PHP 8)

snmpwalk — Scarica tutti gli oggetti SNMP da un agente

Descrizione

snmpwalk(
    string $hostname,
    string $community,
    string $object_id,
    int $timeout = ?,
    int $retries = ?
): array

La funzione restituisce un array con i valori degli oggetti SNMP utilizzando object_id come punto di partenza, oppure false se si verifica un errore.

La funzione snmpwalk() viene utilizzata per leggere tutti i valori dall'agente SNMP specificato nel parametro hostname. Il parametro Community specifica la comunità per l'agente. Con l'impostazione a null del parametro object_id si indica la radice dell'albero degli oggetti SNMP, pertanto saranno restituiti nell'array tutti gli oggetti dell'albero. Viceversa se si indica un valore per object_id, sarranno restituiti tutti gli oggetti sottostanti object_id.

<?php
$a = snmpwalk("127.0.0.1", "public", "");
?>

L'esempio precedente mostra come recuperare tutti gli oggetti SNMP dall'agente attivo sulla macchina locale. Tramite un loop (illustrato di seguito) si può accedere a tutti i valori.

<?php
for ($i=0; $i < count($a); $i++) {
    echo $a[$i];
}
?>

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User Contributed Notes 10 notes

down

steve at ourabode dot org ¶

22 years ago

Timeout is in MICRO seconds.
1,000,000 &micros = 1 s

down

Lars Troen ¶

21 years ago

Note that there's different behaviuor in php snmpwalk and ucd snmpwalk. If you try to walk an oid that has one value not under a subkey of the walked oid, ucd snmpwalk will return the value while php's snmpwalk will not.

down

anders at ei dot nu ¶

21 years ago

It would be nice to be able to specify what snmp version to use ( 1,2c,3 )

For now, I'ts hardcoded in ext/snmp/snmp.c

change session.version from 1 to 2c or 3 if you need for now..

i.e 

session.version = SNMP_VERSION_1;

to:
session.version = SNMP_VERSION_2c;

down

smcbride at msn dot com ¶

2 months ago

snmpwalk and other snmp functions really need to support an optional port.

In the corporate world it is very common to change the port for SNMP from 161 to some other port for security.  It is a simple security obfuscation, but a lot of bots will scan well known ports for attack vectors.  For example, we used to change ours to something like 1161 just to prevent making it easy.

down

layer2 at www dot com ¶

23 years ago

Something to care about in dealing with snmpwalk:<BR>





While walking the MIB, snmpwalk puts info that gets into an array, and that is correct.<BR>





The trouble happened when snmpwalk needs to collect information from instances that contains subinstances (i.e. walking .1.2.3.4.5 and having instances like 1.1, 1.2, 1.3): in this case it gets info and passes into an array, but when walking the array, each value is preceeded by 'Counter32: '.<BR>





I've tested this in many ways and it always happened the same way.

down

john at antefacto dot com ¶

23 years ago

Ah. That's why all of our SNMP stuff was timing out anytime there was any load on the system. Sigh. A waste of two weeks trying to debug snmp....



 Even the snmpcmd manpage doesn't give a

unit for timeout.

down

billf at freebsd dot org ¶

23 years ago

for the poster wondering what the

timeout field was measured in:



from the ucd-snmp header file snmp_api.h:



    long    timeout; 

    /* Number of uS until first timeout

    then exponential backoff */

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jmartinson(AT_nospam)info234.com ¶

23 years ago

A quick router device view:



<?

include "header.html";



$host = "auscr1";

$community = "tellme";

                     

$sysDescr = snmpget("$host","$community","system.sysDescr.0");

$ifDescr = snmpwalk("$host","$community","interfaces.ifTable.ifEntry.ifDescr");

$ifIndex = snmpwalk("$host","$community","interfaces.ifTable.ifEntry.ifIndex");

$ifAdminStatus = snmpwalk("$host","$community","interfaces.ifTable.ifEntry.ifAdminStatus");

$ifOperStatus = snmpwalk("$host","$community","interfaces.ifTable.ifEntry.ifOperStatus");

$ifLastChange = snmpwalk("$host","$community","interfaces.ifTable.ifEntry.ifLastChange");

                                          

print "<table border=1 bgcolor=#ffffff><tr><td>$host</td></tr></table><br>";

print "<table border=1 bgcolor=#ffffff><tr><td>$sysDescr</td></tr></table><br>";

print "<table border=1 bgcolor=#ffffff>";

print "<tr> 

        <td>ifIndex</td>

        <td>ifDescr</td>

        <td>ifAdminStatus</td>

        <td>ifOperStatus</td>

        <td>ifLastChange</td>

        </tr>";

             

for ($i=0; $i<count($ifIndex); $i++) {

        print "<tr>";

        print "<td>$ifIndex[$i]</td>";

        print "<td>$ifDescr[$i]</td>";

        print "<td>$ifAdminStatus[$i]</td>";

        print "<td>$ifOperStatus[$i]</td>";

        print "<td>$ifLastChange[$i]</td>";

        print "</tr>";

}            

print "</table>";



?>

down

-3

http://mike.eire.ca ¶

19 years ago

I found on Windows (PHP 5) an empty string did not return anything, it just timed out.  I had to use null instead:

<?php
$a = snmpwalk("127.0.0.1", "public", null);
?>

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-4

bobby [dot] clark [at] eku [dot] edu ¶

21 years ago

I had to use an object_id like these.
'SNMPv2-MIB::system.sysDescr.0'
'IF-MIB::interfaces.ifTable.ifEntry.ifAdminStatus'

<?php
$host = '192.168.1.1';
$community = 'public';
$object_id = 'IF-MIB::interfaces.ifTables.ifEntry.ifAdminStatus';

$sysdesc = snmpwalk($host, $community', $object_id);
print_r($sysdesc);
?>

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