phpSNMP

phpSNMP is an SNMP implementation based on libsnmp, which is written in Python. It has been ported to 100% pure PHP.

Why not just use the SNMP extension?

The data return from the SNMP extension is not uniform accross platforms with different MIBs installed.
The SNMP extension does not support traps.
The SNMP extension does not support parallel gets.
The SNMP extension does not support bulk gets.
The SNMP extension results in semi-frequent core dumps on FreeBSD (I think it has something to do with threads).
The SNMP extension requires building yet another extension into PHP.

Dependencies

phpSNMP requires PHP 4.3.0 or better with sockets enabled. Mcrypt is required for privacy in SNMP v3.

phpSNMP is known to work on FreeBSD, Linux and Windows.

NOTE: users of previous versions should modify their code to use the version constants rather than hardcoded numbers. $snmp->version = 2; will not have the desired effect. Use $snmp->version = SNMP_VERSION_2;

Download

TODO

v3 needs to support more than USM.
More, better documentation.
Optimize code for speed.

FAQ

What are parallel gets?
Parallel gets is a technique used to poll several devices at the same time. Basically, it sends out get requests sequentially and does not wait for the response. As responses are returned, they are recorded.
What are bulk gets?
Bulk gets are a SNMP v2 construct that allows the retrieval of several objects from a single host. Watch out! Bulk gets are not exatly the same as a series of gets. They behave more like a get next request (what walks are built from), so you may have to specify the OID just before the one you want.

Is phpSNMP faster than the PHP SNMP extension?
Generally, no. It does, however, shine when used in ways the PHP SNMP extension does not support. Parallel gets and bulk gets are faster when sufficiently large requests are made. Below are some benchmark results of 1363 cable modems.

Benchmarks:	1363 GETs	1363 WALKs
PHP SNMP extension:	522.7428	1076.4026
NetSNMP shell call:	713.8399	1250.5760
phpSNMP:	1770.8982	3752.9192
phpSNMP parallel:	31.5648	256.4561

Why doesn't phpSNMP behave like the PHP SNMP extension?
Generally, if phpSNMP behaves differently, you found a bug. I say this because NET SNMP has been around for quite a while, and phpSNMP has not. If you find a bug, I want to hear about it.
How does [insert feature] work?
I would be glad to answer any questions you might have. If you have questions, it probably means I need to document that area better.
How do I force phpSNMP to generate length encodings compatible with some (broken) Cisco software?
Some Cisco software always encodes the length field as a short integer. While this is always read correctly by devices, it neglects the shorter more standard encoding. If the cisco software merely wrote it this way, nobody would care; but it cannot read other correctly encoded length fields. As a work-around, simply define('SNMP_SHORT_INT_LENGTH', 1);. That will tell phpSNMP to always encode lengths as short integers.
What is the MIB compiler?
The MIB compiler allows you to customize the oid_format function. The oid_format function allows translation between numeric and textual OIDs.
How can I probe a single device in parallel?
In general, you can't. SNMP was not designed to work that way. Try using bulk probes.

Usage


<?php
  error_reporting(E_ALL);
  ini_set('memory_limit', '256M');

  require('snmp.php');

  $snmp = new snmp();

  $oid = '.1.3.6.1.2.1.69.1.1.3';
  $oid = $argv[1];

  // test the oid_format function
  $z = oid_format($oid, OID_TEXT);
  $zz = oid_format($z, OID_NUMERIC);
  echo "$oid => $z => $zz\n";
exit;

  $ip = '172.16.0.116';         // ip address or hostname
  $ips = array($ip, '172.16.0.64');    // array of ip addresses or hostnames
  $community = 'public';        // community string
  $oid = '.1.3.6.1.2.1.1';        // only numerical oids are supported
  $oids = array('.1.3.6.1.2.1.1.1', '.1.3.6.1.2.1.1.3');

  $snmp = new snmp();

  $snmp->version = SNMP_VERSION_3;
  print_r($snmp->get('localhost', '.1.3.6.1.2.1.1.3.0', array('v3_flags'=>SNMP_AUTH_PRIV, 'v3_user'=>'v3user',
                                                              'v3_auth'=>'authpassword', 'v3_priv'=>'privpassword')));

  $snmp->version = SNMP_VERSION_2;

  print_r($snmp->walk($ip, $oid, $community));
  print_r($snmp->multi_walk($ips, $oid, $community));

  // get system uptime
  print_r($snmp->get($ip, '.1.3.6.1.2.1.1.3.0', $community));
  print_r($snmp->multi_get($ips, '.1.3.6.1.2.1.1.3.0', $community));

  // bulk get
  print_r($snmp->bulk_get($ip, $oids));

  // reset cable modem(s)
  $oid = '.1.3.6.1.3.83.1.1.4.0.1.1.3.0';
  $snmp->set($ip, $oid, 1, 'i', 'private');
  $snmp->multi_set($ips, $oid, 1, 'i', 'private');

  // send a trap
  $ip = '123.45.12.3';
  $community = 'public';
  $varbind = $snmp->build_varbind('.1.3.6.1.3.83.1.1.4.1', 17, 'i');
  $enterprise = '.1.3.6.1.3.83.1.1.4.0.1.1.3.0';
  $agent = '127.0.0.1';
  $trap_type = TRAP_LINKUP;
  $specific_trap_type = 2;
  $uptime = 123;

  $snmp->trap($ip, $community, $varbind, $enterprise, $agent, $trap_type, $specific_trap_type, $uptime);
?>