example.js

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  example.js asn1ber.js snmp.js

- # example.js

- ¶

  ## Example code for node-snmp-native.

- ¶

  This file contains examples of how to use the library.

  ## Basic setup

- ¶

  The snmp object is the main entry point to the library.

      var snmp = require('snmp-native');

      var util = require('util');

      var host = 'localhost';
      var community = 'public';

- ¶

  A session is required to communicate with an agent.

      var session = new snmp.Session({ host: host, community: community });

- ¶

  All OIDs are represented as integer arrays. There is no interpretation of string or MIB names. This here is the OID for sysDescr.0.

      var oid = [1, 3, 6, 1, 2, 1, 1, 1, 0];

- ¶

  ## Getting a single value

- ¶

  This is how you issue a simple get request.

      session.get({ oid: oid }, function (err, varbinds) {
          var vb;

          if (err) {

- ¶

  If there is an error, such as an SNMP timeout, we'll end up here.

              console.log(err);
          } else {
              vb = varbinds[0];
              console.log('The system description is "' + vb.value + '"');
          }

- ¶

  The session must be closed when you're done with it.

          session.close();
      });

- ¶

  ## Parsing an OID string and getting an entire tree

- ¶

  Here we convert an OID from string representation to array. This is the base OID for the ifName tree.

      var oidStr = '.1.3.6.1.2.1.31.1.1.1.1';
      oid = oidStr
          .split('.')
          .filter(function (s) { return s.length > 0; })
          .map(function (s) { return parseInt(s, 10); });

- ¶

  You can also get an entire subtree (an SNMP walk).

      var session2 = new snmp.Session({ host: host, community: community });
      session2.getSubtree({ oid: oid }, function (err, varbinds) {
          if (err) {

- ¶

  If there is an error, such as an SNMP timeout, we'll end up here.

              console.log(err);
          } else {

- ¶

  This is the list of varbinds.

              varbinds.forEach(function (vb) {
                  console.log('Name of interface ' + vb.oid[vb.oid.length - 1]  + ' is "' + vb.value + '"');
              });
          }

          session2.close();
      });

- ¶

  You can get all of a collection of OIDs in one go. The semantics is similar to getSubtree.

      var session3 = new snmp.Session({ host: host, community: community });
      var oids = [[1, 3, 6, 1, 2, 1, 1, 1, 0], [1, 3, 6, 1, 2, 1, 1, 2, 0]];
      session3.getAll({ oids: oids }, function (err, varbinds) {
          varbinds.forEach(function (vb) {
              console.log(vb.oid + ' = ' + vb.value);
          });
          session3.close();
      });

- ¶

  You can also create a destination-less "session" to use on multiple hosts. This is useful for conserving file descriptors when talking to a large number of hosts. This example scans the 192.168.1.0/24 network for SNMP responders.

      var session4 = new snmp.Session({ community: community }); // New session without host parameter. We set community to avoid repeating it later.
      var oid = [1, 3, 6, 1, 2, 1, 1, 1, 0]; // sysDescr.0
      var cnt = 254; // Expected number of callbacks.
      for (var i = 1; i < 255; i++) {
          /*jshint loopfunc:true */

- ¶

  We need a function to get a closure over i.

          (function (host) {
              session4.get({ oid: oid, host: host }, function (err, vbs) {
                  if (err) {

- ¶

  Probably a Timeout.

                      console.log('Error for ' + host + ': ' + err);
                  } else {

- ¶

  Print the returned value (sysDescr).

                      var vb = vbs[0];
                      console.log(host + ': ' + vb.oid + ' = ' + vb.value);
                  }

                  if (--cnt === 0) {

- ¶

  All requests have returned, time to close the session and exit.

                      session4.close();
                  }
              });
          }('192.168.1.' + i));
      }

- ¶

  ## Example output

- ¶

  The expected output is something along these lines. Note that the asynchronicity results in the responses being printed in a different order that what you might guess from the above code.

      /*
      1,3,6,1,2,1,1,1,0 = Solaris anto.nym.se 11.0 physical
      1,3,6,1,2,1,1,2,0 = 1,3,6,1,4,1,8072,3,2,3
      The system description is "Solaris anto.nym.se 11.0 physical"
      Name of interface 1 is "lo0"
      Name of interface 2 is "e1000g0"
      Name of interface 3 is "vboxnet0"
      Name of interface 4 is "e1000g1"
      Name of interface 5 is "he0"
      Name of interface 6 is "nym0"
      <... lots of timeouts for the scan stuff ...>
      */