JavaScript implementation of the Simple Network Management Protocol (SNMP)
npm install net-snmpThis module implements versions 1, 2c and 3 of the [Simple Network Management
Protocol (SNMP)][SNMP].
Read this in other languages: English, 简体中文.
This module is installed using [node package manager (npm)][npm]:
``bash`
npm install net-snmp
It is loaded using the require() function:
`js`
var snmp = require ("net-snmp");
Sessions to remote hosts can then be created and used to perform SNMP requests
and send SNMP traps or informs:
`js
var session = snmp.createSession ("127.0.0.1", "public");
var oids = ["1.3.6.1.2.1.1.5.0", "1.3.6.1.2.1.1.6.0"];
session.get (oids, function (error, varbinds) {
if (error) {
console.error (error);
} else {
for (var i = 0; i < varbinds.length; i++) {
if (snmp.isVarbindError (varbinds[i])) {
console.error (snmp.varbindError (varbinds[i]));
} else {
console.log (varbinds[i].oid + " = " + varbinds[i].value);
}
}
}
session.close ();
});
session.trap (snmp.TrapType.LinkDown, function (error) {
if (error) {
console.error (error);
}
});
`
[SNMP]: http://en.wikipedia.org/wiki/Simple_Network_Management_Protocol "SNMP"
[npm]: https://npmjs.org/ "npm"
RFC 3413 describes five types of SNMP applications:
1. Command Generator Applications — which initiate read or write requests
2. Command Responder Applications — which respond to received read or write requests
3. Notification Originator Applications — which generate notifications (traps or informs)
4. Notification Receiver Applications — which receive notifications (traps or informs)
5. Proxy Forwarder Applications — which forward SNMP messages
This library provides support for all of the above applications, with the documentation
for each shown in this table:
| Application | Common Use | Documentation |
| ----------- | ---------- | ------------- |
| Command Generator | NMS / SNMP tools | Application: Command & Notification Generator |
| Command Responder | SNMP agents | Application: SNMP Agent |
| Notification Originator | SNMP agents / NMS-to-NMS notifications | Application: Command & Notification Generator |
| Notification Receiver | NMS | Application: Notification Receiver |
| Proxy Forwarder | SNMP agents | Agent Forwarder Module |
* Support for all SNMP versions: SNMPv1, SNMPv2c and SNMPv3
* SNMPv3 message authentication using MD5 or SHA, and privacy using DES or AES encryption
* Community-based and user-based authorization
* SNMP initiator for all relevant protocol operations: Get, GetNext, GetBulk, Set, Trap, Inform
* Convenience methods for MIB "walking", subtree collection, table and table column collection
* SNMPv3 context support
* Notification receiver for traps and informs
* MIB parsing and MIB module store
* Translation between numeric and named OIDs
* SNMP agent with MIB management for both scalar and tabular data
* Agent table index support for non-integer keys, foreign keys, composite keys and table augmentation
* Agent support for "RowStatus" protocol-based creation and deletion of table rows
* Agent support for these MIB constraints: MAX-ACCESS, integer ranges, string sizes, integer enumerations
* SNMP proxy forwarder for agent
* AgentX subagent
* IPv4 and IPv6
This module aims to be fully compliant with the following RFCs:
* [1098][1098] - A Simple Network Management Protocol (version 1)
* [1155][1155] - Structure and Identification of Management Information
* [2571][2571] - Agent Extensibility (AgentX) Protocol Version 1
* [2578][2578] - Structure of Management Information Version 2 (SMIv2)
* [3413][3413] - Simple Network Management Protocol (SNMP) Applications
* [3414][3414] - User-based Security Model (USM) for version 3 of the
Simple Network Management Protocol (SNMPv3)
* [3416][3416] - Version 2 of the Protocol Operations for the Simple
Network Management Protocol (SNMP)
* [3417][3417] - Transport Mappings for the Simple Network Management
Protocol (SNMP)
* [3826][3826] - The Advanced Encryption Standard (AES) Cipher Algorithm
in the SNMP User-based Security Model
[1155]: https://tools.ietf.org/rfc/rfc1155.txt "RFC 1155"
[1098]: https://tools.ietf.org/rfc/rfc1098.txt "RFC 1098"
[2571]: https://tools.ietf.org/rfc/rfc2578.txt "RFC 2571"
[2578]: https://tools.ietf.org/rfc/rfc2578.txt "RFC 2578"
[3413]: https://tools.ietf.org/rfc/rfc3413.txt "RFC 3413"
[3414]: https://tools.ietf.org/rfc/rfc3414.txt "RFC 3414"
[3416]: https://tools.ietf.org/rfc/rfc3416.txt "RFC 3416"
[3417]: https://tools.ietf.org/rfc/rfc3417.txt "RFC 3417"
[3826]: https://tools.ietf.org/rfc/rfc3826.txt "RFC 3826"
The following sections describe constants exported and used by this module.
These constants are used to specify which of version supported by this module
should be used.
This object contains constants for all valid values the error-status field in
response PDUs can hold. If when parsing a PDU the error-index field contains
a value not defined in this object the constant snmp.ErrorStatus.GeneralError
will be used instead of the value in the error-status field. The following
constants are defined in this object:
* NoError
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
This object contains constants used to specify syntax for varbind objects,
e.g.:
`js`
var varbind = {
oid: "1.3.6.1.2.1.1.4.0",
type: snmp.ObjectType.OctetString,
value: "user.name@domain.name"
};
The following constants are defined in this object:
* Boolean
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
This object contains constants used to specify a type of SNMP trap. These
constants are passed to the trap() and inform() methods exposed by theSession class. The following constants are defined in this object:
* ColdStart
*
*
*
*
*
*
This object contains constants used to identify the SNMP PDU types specified
in RFC 3416. The values, along with their numeric codes, are:
* 160 - GetRequest
*
*
*
*
*
*
*
*
This object contains constants to specify the security of an SNMPv3 message as per
RFC 3414:
* noAuthNoPriv - for no message authentication or encryptionauthNoPriv
* - for message authentication and no encryptionauthPriv
* - for message authentication and encryption
This object contains constants to select a supported digest algorithm for SNMPv3
messages that require authentication:
* md5 - for HMAC-MD5 message authenticationsha
* - for HMAC-SHA-1 message authenticationsha224
* - for HMAC-SHA-224 message authenticationsha256
* - for HMAC-SHA-256 message authenticationsha384
* - for HMAC-SHA-384 message authenticationsha512
* - for HMAC-SHA-512 message authentication
MD5 and SHA (actually SHA-1) are the hash algorithms specified in the original
SNMPv3 User-Based Security Model RFC (RFC 3414); the other four were added later
in RFC 7860.
This object contains constants to select a supported encryption algorithm for
SNMPv3 messages that require privacy:
* des - for DES encryption (CBC-DES)aes
* - for 128-bit AES encryption (CFB-AES-128)aes256b
* - for 256-bit AES encryption (CFB-AES-256) with "Blumenthal" key localizationaes256r
* - for 256-bit AES encryption (CFB-AES-256) with "Reeder" key localization
DES is the sole encryption algorithm specified in the original SNMPv3 User-Based
Security Model RFC (RFC 3414); 128-bit AES for SNMPv3 was added later in RFC 3826.
256-bit AES has not been standardized, and as such comes with two varieties of key
localization. Cisco and a number of other vendors commonly use the "Reeder" key
localization variant. Other encryption algorithms are not supported.
When using SNMPv3 with DES as the privacy protocol (snmp.PrivProtocols.des) on Node.js v17 or later, you may encounter the following error:
`
"error": {
"library": "digital envelope routines",
"reason": "unsupported",
"code": "ERR_OSSL_EVP_UNSUPPORTED",
"message": "error:0308010C:digital envelope routines::unsupported",
"stack": ["Error: error:0308010C:digital envelope routines::unsupported",
"at Cipheriv.createCipherBase (node:internal/crypto/cipher:121:19)",
...
}
This occurs because newer versions of Node.js have deprecated support for the DES algorithm in OpenSSL for security reasons.
Workaround:
If you need to communicate with legacy devices that only support DES for SNMPv3, you can run Node.js with the --openssl-legacy-provider flag:
`bash`
node --openssl-legacy-provider your-app.js
Whenever possible, it's recommended to use more secure encryption methods like AES (snmp.PrivProtocols.aes) instead of DES.
The Agent Extensibility (AgentX) Protocol specifies these PDUs in RFC 2741:
* 1 - Open
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
* None - no access control for defined communities and usersSimple
* - simple access control of levels "read-only" or "read-write" for defined communites and users
- None - no access granted to the community or userReadOnly
- - read-only access granted to the community or userReadWrite
- - read-write access granted to the community or user
-
-
-
- snmp.RowStatus
Status values
-
-
- Actions
-
-
- snmp.ResponseInvalidCode
-
-
-
-
-
-
-
-
-
-
-
-
- snmp.OidFormat
-
-
- OID Strings & Varbinds
Some parts of this module accept simple OID strings, e.g.:
js
var oid = "1.3.6.1.2.1.1.5.0";
`Other parts take an OID string, it's type and value. This is collectively
referred to as a varbind, and is specified as an object, e.g.:
js
var varbind = {
oid: "1.3.6.1.2.1.1.5.0",
type: snmp.ObjectType.OctetString,
value: new Buffer ("host1")
};
`The
parameter is one of the constants defined in the snmp.ObjectType
object.The JavaScript
and false keywords are used for the values of varbinds
with type Boolean.All integer based types are specified as expected (this includes
Integer,
Counter, Gauge, TimeTicks, Integer32, Counter32, Gauge32, and
Unsigned32), e.g. -128 or 100.Since JavaScript does not offer full 64 bit integer support objects with type
Counter64 cannot be supported in the same way as other integer types,
instead [Node.js][nodejs] Buffer objects are used. Users are responsible for
producing (i.e. for set() requests) and consuming (i.e. the varbinds passed
to callback functions) Buffer objects. That is, this module does not work
with 64 bit integers, it simply treats them as opaque Buffer objects.Dotted decimal strings are used for the values of varbinds with type
OID,
e.g. 1.3.6.1.2.1.1.5.0.Dotted quad formatted strings are used for the values of varbinds with type
IpAddress, e.g. 192.168.1.1.[Node.js][nodejs]
Buffer objects are used for the values of varbinds with
type Opaque and OctetString. For varbinds with type OctetString this
module will accept JavaScript strings, but will always give back Buffer
objects.The
, NoSuchInstance and EndOfMibView types are used to
indicate an error condition. Currently there is no reason for users of this
module to to build varbinds using these types.[nodejs]: http://nodejs.org "Node.js"
Callback Functions & Error Handling
Most of the request methods exposed by this module require a mandatory
callback function. This function is called once a request has been processed.
This could be because an error occurred when processing the request, a trap
has been dispatched or a successful response was received.
The first parameter to every callback is an error object. In the case no
error occurred this parameter will be "null" indicating no error, e.g.:
`js
function responseCb (error, varbinds) {
if (error) {
console.error (error);
} else {
// no error, do something with varbinds
}
}
`When defined, the
parameter is always an instance of the Error class,
or a sub-class described in one of the sub-sections contained in this section.The semantics of error handling is slightly different between SNMP version
1 and subsequent versions 2c and 3. In SNMP version 1 if an error occurs when
calculating the value for one OID the request as a whole will fail, i.e. no
OIDs will have a value.
This failure manifests itself within the error-status and error-index fields
of the response. When the error-status field in the response is non-zero,
i.e. not
snmp.ErrorStatus.NoError the callback will be called with error
defined detailing the error.Requests made with SNMP version 1 can simply assume all OIDs have a value when
no error object is passed to the
, i.e.:`js
var oids = ["1.3.6.1.2.1.1.5.0", "1.3.6.1.2.1.1.6.0"];session.get (oids, function (error, varbinds) {
if (error) {
console.error (error.toString ());
} else {
var sysName = varbinds[0].value; // this WILL have a value
}
});
`In SNMP versions 2c and 3, instead of using the error-status and error-index
fields of the response to signal an error, the value for the varbind placed in the
response for an OID will have an object syntax describing an error. The
error-status and error-index fields of the response will indicate the request
was successul, i.e.
.This changes the way in which error checking is performed in the
callback.
When using SNMP version 2c each varbind must be checked to see if its value
was computed and returned successfully:`js
var oids = ["1.3.6.1.2.1.1.5.0", "1.3.6.1.2.1.1.6.0"];session.get (oids, function (error, varbinds) {
if (error) {
console.error (error.toString ());
} else {
if (varbinds[0].type != snmp.ErrorStatus.NoSuchObject
&& varbinds[0].type != snmp.ErrorStatus.NoSuchInstance
&& varbinds[0].type != snmp.ErrorStatus.EndOfMibView) {
var sysName = varbinds[0].value;
} else {
console.error (snmp.ObjectType[varbinds[0].type] + ": "
+ varbinds[0].oid);
}
}
});
`This module exports two functions and promotes a specifc pattern to make error
checking a little simpler. Firstly, regardless of version in use varbinds can
always be checked. This results in a generic
that can be used for
both versions.The
isVarbindError() function can be used to determine if a varbind has an
error condition. This function takes a single varbind parameter and returns
true if the varbind has an error condition, otherwise false. The exported
varbindError() function can then be used to obtain the error string
describing the error, which will include the OID for the varbind:`js
session.get (oids, function (error, varbinds) {
if (error) {
console.error (error.toString ());
} else {
if (snmp.isVarbindError (varbinds[0])) {
console.error (snmp.varbindError (varbinds[0]));
} else {
var sysName = varbinds[0].value;
}
}
});
`If the
function is called with a varbind for which
isVarbindError would return false, the string NotAnError will be returned
appended with the related OID.The sections following defines the error classes used by this module.
snmp.RequestFailedError
This error indicates a remote host failed to process a request. The exposed
message attribute will contain a detailed error message. This error also
exposes a status attribute which contains the error-index value from a
response. This will be one of the constants defined in the
snmp.ErrorStatus object.snmp.RequestInvalidError
This error indicates a failure to render a request message before it could be
sent. The error can also indicate that a parameter provided was invalid.
The exposed
message attribute will contain a detailed error message.snmp.RequestTimedOutError
This error states that no response was received for a particular request. The
exposed
message attribute will contain the value Request timed out.snmp.ResponseInvalidError
This error indicates a failure to parse a response message. The
exposed
message attribute will contain a detailed error message, and
as a sub-class of Error, its toString() method will yield that
message attribute.An error of this class will always additionally include a
code
attribute (one of the values in ); and in some
cases, also have an info attribute which provides code-specific
supplemental information. An authentication error, for example -- code
ResponseInvalidCode.EAuthFailure -- will contain a map in info
with the attempted authentication data which failed to authenticate.snmp.ProcessingError
If a receiver or an agent receives a packet it is unable to decode,
then it will produce a
containing:
* rinfo information on the origin of the packet,
* a buffer containing the packet contents, and
* an error containing the original error encountered during processing.Application: Command & Notification Generator
This library provides a
Session class to provide support for building
"Command Generator" and "Notification Originator" SNMP applications.All SNMP requests are made using an instance of the
Session class. This
module exports two functions that are used to create instances of the
Session class: *
createSession() - for v1 and v2c sessions
* createV3Session() - for v3 sessionssnmp.createSession ([target], [community], [options])
The
createSession() function instantiates and returns an instance of the
Session class for SNMPv1 or SNMPv2c:`js
// Default options
var options = {
port: 161,
retries: 1,
timeout: 5000,
backoff: 1.0,
transport: "udp4",
trapPort: 162,
version: snmp.Version1,
backwardsGetNexts: true,
reportOidMismatchErrors: false,
idBitsSize: 32,
dgramModule: dgram,
strictIntRangeChecks: false
};var session = snmp.createSession ("127.0.0.1", "public", options);
`The optional
parameter defaults to 127.0.0.1. The optional
community parameter defaults to public. The optional options parameter
is an object, and can contain the following items: *
port - UDP port to send requests too, defaults to 161
* - Number of times to re-send a request, defaults to 1
* - IP address from which SNMP requests should originate,
there is no default for this option, the operating system will select an
appropriate source address when the SNMP request is sent
* sourcePort - UDP port from which SNMP requests should originate, defaults
to an ephemeral port selected by the operation system
* timeout - Number of milliseconds to wait for a response before re-trying
or failing, defaults to 5000
* - The factor by which to increase the timeout for every retry, defaults to 1 for
no increase
* transport - Specify the transport to use, can be either udp4 or udp6,
defaults to udp4
* - UDP port to send traps and informs too, defaults to 162
* - Either snmp.Version1 or snmp.Version2c, defaults to
snmp.Version1
* - boolean to allow GetNext operations to retrieve lexicographically
preceding OIDs, defaults to true
* - boolean to allow error reporting of OID mismatches between
requests and responses, defaults to false
* - Either 16 or 32, defaults to 32. Used to reduce the size
of the generated id for compatibility with some older devices.
* dgramModule – A module that is interface-compatible with the Node.js dgram module.
This can be used to extend or override the default UDP socket behavior by supplying
a custom or wrapped implementation of dgram.
* strictIntRangeChecks - boolean to enable min/max range checks in readInt32 and readUint32.
When set to true, out-of-range values will throw, otherwise they will be logged via debug if debug is enabled.
Note that the option is toggled at module level when a session is created. If you create multiple sessions
with conflicting settings, the most recently created session’s setting will apply process-wide.
When a session has been finished with it should be closed:
`js
session.close ();
`snmp.createV3Session (target, user, [options])
The
function instantiates and returns an instance of the
same Session class as createSession(), only instead initialized for SNMPv3:`js
// Default options for v3
var options = {
port: 161,
retries: 1,
timeout: 5000,
transport: "udp4",
trapPort: 162,
version: snmp.Version3,
engineID: "8000B98380XXXXXXXXXXXXXXXXXXXXXXXX", // where the X's are random hex digits
backwardsGetNexts: true,
reportOidMismatchErrors: false,
idBitsSize: 32,
context: "",
strictIntRangeChecks: false
};// Example user
var user = {
name: "blinkybill",
level: snmp.SecurityLevel.authPriv,
authProtocol: snmp.AuthProtocols.sha,
authKey: "madeahash",
privProtocol: snmp.PrivProtocols.des,
privKey: "privycouncil"
};
var session = snmp.createV3Session ("127.0.0.1", user, options);
`The
and user parameters are mandatory. The optional options parameter
has the same meaning as for the createSession() call. The one additional field
in the options parameter is the context field, which adds an SNMPv3 context to
the session.The
user object must contain a name and level field. The level field can
take these values from the snmp.SecurityLevel object:
* snmp.SecurityLevel.noAuthNoPriv - for no message authentication or encryption
* snmp.SecurityLevel.authNoPriv - for message authentication and no encryption
* snmp.SecurityLevel.authPriv - for message authentication and encryptionThe meaning of these are as per RFC3414. If the
level supplied is authNoPriv or
authPriv, then the authProtocol and authKey fields must also be present. The
authProtocol field can take values from the snmp.AuthProtocols object:
* snmp.AuthProtocols.md5 - for MD5 message authentication
* snmp.AuthProtocols.sha - for SHA message authenticationIf the
level supplied is authPriv, then the privProtocol and privKey fields
must also be present. The privProtocol field can take values from the
snmp.PrivProtocols object:
* snmp.PrivProtocols.des - for DES encryption
* snmp.PrivProtocols.aes - for AES encryptionOnce a v3 session is created, the same set of
session methods are available as
for v1 and v2c.session.on ("close", callback)
The
close event is emitted by the session when the session's underlying UDP
socket is closed.No arguments are passed to the callback.
Before this event is emitted all outstanding requests are cancelled, resulting
in the failure of each outstanding request. The error passed back through to
each request will be an instance of the
Error class with the errors
message attribute set to Socket forcibly closed.The following example prints a message to the console when a session's
underlying UDP socket is closed:
`js
session.on ("close", function () {
console.log ("socket closed");
});
`session.on ("error", callback)
The
event is emitted by the session when the session's underlying UDP
socket emits an error.The following arguments will be passed to the
callback function: *
error - An instance of the Error class, the exposed message attribute
will contain a detailed error message.The following example prints a message to the console when an error occurs
with a session's underlying UDP socket, the session is then closed:
`js
session.on ("error", function (error) {
console.log (error.toString ());
session.close ();
});
`session.close ()
The
method closes the sessions underlying UDP socket. This will
result in the close event being emitted by the sessions underlying UDP
socket which is passed through to the session, resulting in the session also
emitting a close event.The following example closes a sessions underlying UDP socket:
`js
session.close ();
`session.get (oids, callback)
The
method fetches the value for one or more OIDs.The
oids parameter is an array of OID strings. The callback function is
called once the request is complete. The following arguments will be passed
to the callback function: *
error - Instance of the Error class or a sub-class, or null if no
error occurred
* varbinds - Array of varbinds, will not be provided if an error occurredThe varbind in position N in the
varbinds array will correspond to the OID
in position N in the oids array in the request.Each varbind must be checked for an error condition using the
snmp.isVarbindError() function when using SNMP version 2c.The following example fetches values for the sysName (
1.3.6.1.2.1.1.5.0) and
sysLocation (1.3.6.1.2.1.1.6.0) OIDs:`js
var oids = ["1.3.6.1.2.1.1.5.0", "1.3.6.1.2.1.1.6.0"];session.get (oids, function (error, varbinds) {
if (error) {
console.error (error.toString ());
} else {
for (var i = 0; i < varbinds.length; i++) {
// for version 1 we can assume all OIDs were successful
console.log (varbinds[i].oid + "|" + varbinds[i].value);
// for version 2c we must check each OID for an error condition
if (snmp.isVarbindError (varbinds[i]))
console.error (snmp.varbindError (varbinds[i]));
else
console.log (varbinds[i].oid + "|" + varbinds[i].value);
}
}
});
`session.getBulk (oids, [nonRepeaters], [maxRepetitions], callback)
The
method fetches the value for the OIDs lexicographically
following one or more OIDs in the MIB tree.The
oids parameter is an array of OID strings. The optional nonRepeaters
parameter specifies the number of OIDs in the parameter for which only
1 varbind should be returned, and defaults to 0. For each remaining OID
in the oids parameter the optional maxRepetitions parameter specifies how
many OIDs lexicographically following an OID for which varbinds should be
fetched, and defaults to 20.The
callback function is called once the request is complete. The following
arguments will be passed to the callback function: *
error - Instance of the Error class or a sub-class, or null if no
error occurred
* varbinds - Array of varbinds, will not be provided if an error occurredThe varbind in position N in the
varbinds array will correspond to the OID
in position N in the oids array in the request.For for the first
nonRepeaters items in varbinds each item will be a
single varbind. For all remaining items in varbinds each item will be an
array of varbinds - this makes it easy to tie response varbinds with requested
OIDs since response varbinds are grouped and placed in the same position in
varbinds.Each varbind must be checked for an error condition using the
snmp.isVarbindError() function when using SNMP version 2c.The following example fetches values for the OIDs following the sysContact
(
1.3.6.1.2.1.1.4.0) and sysName (1.3.6.1.2.1.1.5.0) OIDs, and up to the
first 20 OIDs in the ifDescr (1.3.6.1.2.1.2.2.1.2) and ifType
(1.3.6.1.2.1.2.2.1.3) columns from the ifTable (1.3.6.1.2.1.2.2) table:`js
var oids = [
"1.3.6.1.2.1.1.4.0",
"1.3.6.1.2.1.1.5.0",
"1.3.6.1.2.1.2.2.1.2",
"1.3.6.1.2.1.2.2.1.3"
];var nonRepeaters = 2;
session.getBulk (oids, nonRepeaters, function (error, varbinds) {
if (error) {
console.error (error.toString ());
} else {
// step through the non-repeaters which are single varbinds
for (var i = 0; i < nonRepeaters; i++) {
if (i >= varbinds.length)
break;
if (snmp.isVarbindError (varbinds[i]))
console.error (snmp.varbindError (varbinds[i]));
else
console.log (varbinds[i].oid + "|" + varbinds[i].value);
}
// then step through the repeaters which are varbind arrays
for (var i = nonRepeaters; i < varbinds.length; i++) {
for (var j = 0; j < varbinds[i].length; j++) {
if (snmp.isVarbindError (varbinds[i][j]))
console.error (snmp.varbindError (varbinds[i][j]));
else
console.log (varbinds[i][j].oid + "|"
+ varbinds[i][j].value);
}
}
}
});
`session.getNext (oids, callback)
The
method fetches the value for the OIDs lexicographically
following one or more OIDs in the MIB tree.The
oids parameter is an array of OID strings. The callback function is
called once the request is complete. The following arguments will be passed
to the callback function: *
error - Instance of the Error class or a sub-class, or null if no
error occurred
* varbinds - Array of varbinds, will not be provided if an error occurredThe varbind in position N in the
varbinds array will correspond to the OID
in position N in the oids array in the request.Each varbind must be checked for an error condition using the
snmp.isVarbindError() function when using SNMP version 2c.The following example fetches values for the next OIDs following the
sysObjectID (
1.3.6.1.2.1.1.1.0) and sysName (1.3.6.1.2.1.1.4.0) OIDs:`js
var oids = [
"1.3.6.1.2.1.1.1.0",
"1.3.6.1.2.1.1.4.0"
];session.getNext (oids, function (error, varbinds) {
if (error) {
console.error (error.toString ());
} else {
for (var i = 0; i < varbinds.length; i++) {
// for version 1 we can assume all OIDs were successful
console.log (varbinds[i].oid + "|" + varbinds[i].value);
// for version 2c we must check each OID for an error condition
if (snmp.isVarbindError (varbinds[i]))
console.error (snmp.varbindError (varbinds[i]));
else
console.log (varbinds[i].oid + "|" + varbinds[i].value);
}
}
});
`session.inform (typeOrOid, [varbinds], [options], callback)
The
method sends a SNMP inform.The
typeOrOid parameter can be one of two types; one of the constants
defined in the snmp.TrapType object (excluding the
snmp.TrapType.EnterpriseSpecific constant), or an OID string.The first varbind to be placed in the request message will be for the
sysUptime.0 OID (1.3.6.1.2.1.1.3.0). The value for this varbind will
be the value returned by the process.uptime () function multiplied by 100
(this can be overridden by providing upTime in the optional options
parameter, as documented below).This will be followed by a second varbind for the
OID
(1.3.6.1.6.3.1.1.4.1.0). The value for this will depend on the typeOrOid
parameter. If a constant is specified the trap OID for the constant will be
used as supplied for the varbinds value, otherwise the OID string specified
will be used as is for the value of the varbind.The optional
parameter is an array of varbinds to include in the
inform request, and defaults to the empty array [].The optional
options parameter is an object, and can contain the following
items: *
upTime - Value of the sysUptime.0 OID (1.3.6.1.2.1.1.3.0) in the
inform, defaults to the value returned by the process.uptime () function
multiplied by 100The
callback function is called once a response to the inform request has
been received, or an error occurred. The following arguments will be passed
to the callback function: *
error - Instance of the Error class or a sub-class, or null if no
error occurred
* varbinds - Array of varbinds, will not be provided if an error occurredThe varbind in position N in the
varbinds array will correspond to the
varbind in position N in the varbinds array in the request. The remote host
should echo back varbinds and their values as specified in the request, and
the varbinds array will contain each varbind as sent back by the remote host.Normally there is no reason to use the contents of the
varbinds parameter
since the varbinds are as they were sent in the request.The following example sends a generic cold-start inform to a remote host,
it does not include any varbinds:
`js
session.inform (snmp.TrapType.ColdStart, function (error) {
if (error)
console.error (error);
});
`The following example sends an enterprise specific inform to a remote host,
and includes two enterprise specific varbinds:
js
var informOid = "1.3.6.1.4.1.2000.1";var varbinds = [
{
oid: "1.3.6.1.4.1.2000.2",
type: snmp.ObjectType.OctetString,
value: "Periodic hardware self-check"
},
{
oid: "1.3.6.1.4.1.2000.3",
type: snmp.ObjectType.OctetString,
value: "hardware-ok"
}
];
// Override sysUpTime, specfiying it as 10 seconds...
var options = {upTime: 1000};
session.inform (informOid, varbinds, options, function (error) {
if (error)
console.error (error);
});
`session.set (varbinds, callback)
The
method sets the value of one or more OIDs.The
varbinds parameter is an array of varbind objects. The callback
function is called once the request is complete. The following arguments will
be passed to the function: *
error - Instance of the Error class or a sub-class, or null if no
error occurred
* varbinds - Array of varbinds, will not be provided if an error occurredThe varbind in position N in the
varbinds array will correspond to the
varbind in position N in the varbinds array in the request. The remote host
should echo back varbinds and their values as specified in the request unless
an error occurred. The varbinds array will contain each varbind as sent
back by the remote host.Each varbind must be checked for an error condition using the
snmp.isVarbindError() function when using SNMP version 2c.The following example sets the value of the sysName (
1.3.6.1.2.1.1.4.0) and
sysLocation (1.3.6.1.2.1.1.6.0) OIDs:`js
var varbinds = [
{
oid: "1.3.6.1.2.1.1.5.0",
type: snmp.ObjectType.OctetString,
value: "host1"
}, {
oid: "1.3.6.1.2.1.1.6.0",
type: snmp.ObjectType.OctetString,
value: "somewhere"
}
];session.set (varbinds, function (error, varbinds) {
if (error) {
console.error (error.toString ());
} else {
for (var i = 0; i < varbinds.length; i++) {
// for version 1 we can assume all OIDs were successful
console.log (varbinds[i].oid + "|" + varbinds[i].value);
// for version 2c we must check each OID for an error condition
if (snmp.isVarbindError (varbinds[i]))
console.error (snmp.varbindError (varbinds[i]));
else
console.log (varbinds[i].oid + "|" + varbinds[i].value);
}
}
});
`session.subtree (oid, [maxRepetitions], feedCallback, doneCallback)
The
method fetches the value for all OIDs lexicographically
following a specified OID in the MIB tree which have the specified OID as
their base. For example, the OIDs sysName (1.3.6.1.2.1.1.5.0) and
sysLocation (1.3.6.1.2.1.1.6.0) both have the same base system
(1.3.6.1.2.1.1) OID.For SNMP version 1 repeated
get() calls are made until the one of the
returned OIDs does not use the specified OID as its base. For SNMP version
2c repeated getBulk() calls are made until the one of the returned OIDs
does no used the specified OID as its base.The
oid parameter is an OID string. The optional maxRepetitions parameter
is passed to getBulk() requests when SNMP version 2c is being used.This method will not call a single callback once all OID values are fetched.
Instead the
feedCallback function will be called each time a response is
received from the remote host. The following arguments will be passed to the
feedCallback function: *
varbinds - Array of varbinds, and will contain at least one varbindEach varbind must be checked for an error condition using the
snmp.isVarbindError() function when using SNMP version 2c.Once at least one of the returned OIDs does not use the specified OID as its
base, or an error has occurred, the
doneCallback function will be called.
The following arguments will be passed to the doneCallback function: *
error - Instance of the Error class or a sub-class, or null if no
error occurredOnce the
doneCallback function has been called the request is complete and
the feedCallback function will no longer be called.If the
feedCallback function returns a true value when called no more
get() or getBulk() method calls will be made and the doneCallback will
be called.The following example fetches all OIDS under the system (
1.3.6.1.2.1.1) OID:`js
var oid = "1.3.6.1.2.1.1";function doneCb (error) {
if (error)
console.error (error.toString ());
}
function feedCb (varbinds) {
for (var i = 0; i < varbinds.length; i++) {
if (snmp.isVarbindError (varbinds[i]))
console.error (snmp.varbindError (varbinds[i]));
else
console.log (varbinds[i].oid + "|" + varbinds[i].value);
}
}
var maxRepetitions = 20;
// The maxRepetitions argument is optional, and will be ignored unless using
// SNMP verison 2c
session.subtree (oid, maxRepetitions, feedCb, doneCb);
`session.table (oid, [maxRepetitions], callback)
The
method fetches the value for all OIDs lexicographically
following a specified OID in the MIB tree which have the specified OID as
their base, much like the subtree() method.This method is designed to fetch conceptual tables, for example the ifTable
(
1.3.6.1.2.1.2.2) table. The values for returned varbinds will be structured
into objects to represent conceptual rows. Each row is then placed into an
object with the rows index being the key, e.g.:`js
var table = {
// Rows keyed by ifIndex (1 and 2 are shown)
1: {
// ifDescr (column 2) and ifType (columnd 3) are shown
2: "interface-1",
3: 6,
...
},
2: {
2: "interface-2",
3: 6,
...
},
...
}
`Internally this method calls the
method to obtain the subtree of
the specified table.The
oid parameter is an OID string. If an OID string is passed which does
not represent a table the resulting object produced to hold table data will be
empty, i.e. it will contain no indexes and rows. The optional
maxRepetitions parameter is passed to the subtree() request.The
callback function will be called once the entire table has been fetched.
The following arguments will be passed to the callback function: *
error - Instance of the Error class or a sub-class, or null if no
error occurred
* table - Object containing object references representing conceptual
rows keyed by index (e.g. for the ifTable table rows are keyed by ifIndex),
each row object will contain values keyed by column number, will not be
provided if an error occurredIf an error occurs with any varbind returned by
subtree() no table will be
passed to the callback function. The reason for failure, and the related
OID string (as returned from a call to the snmp.varbindError() function),
will be passed to the callback function in the error argument as an
instance of the RequestFailedError class.The following example fetches the ifTable (
1.3.6.1.2.1.2.2) table:`js
var oid = "1.3.6.1.2.1.2.2";function sortInt (a, b) {
if (a > b)
return 1;
else if (b > a)
return -1;
else
return 0;
}
function responseCb (error, table) {
if (error) {
console.error (error.toString ());
} else {
// This code is purely used to print rows out in index order,
// ifIndex's are integers so we'll sort them numerically using
// the sortInt() function above
var indexes = [];
for (index in table)
indexes.push (parseInt (index));
indexes.sort (sortInt);
// Use the sorted indexes we've calculated to walk through each
// row in order
for (var i = 0; i < indexes.length; i++) {
// Like indexes we sort by column, so use the same trick here,
// some rows may not have the same columns as other rows, so
// we calculate this per row
var columns = [];
for (column in table[indexes[i]])
columns.push (parseInt (column));
columns.sort (sortInt);
// Print index, then each column indented under the index
console.log ("row for index = " + indexes[i]);
for (var j = 0; j < columns.length; j++) {
console.log (" column " + columns[j] + " = "
+ table[indexes[i]][columns[j]]);
}
}
}
}
var maxRepetitions = 20;
// The maxRepetitions argument is optional, and will be ignored unless using
// SNMP verison 2c
session.table (oid, maxRepetitions, responseCb);
`session.tableColumns (oid, columns, [maxRepetitions], callback)
The
method implements the same interface as the table()
method. However, only the columns specified in the parameter will
be in the resulting table.This method should be used when only selected columns are required, and
will be many times faster than the
table() method since a much smaller
amount of data will be fetched.The following example fetches the ifTable (
1.3.6.1.2.1.2.2) table, and
specifies that only the ifDescr (1.3.6.1.2.1.2.2.1.2) and ifPhysAddress
(1.3.6.1.2.1.2.2.1.6) columns should actually be fetched:`js
var oid = "1.3.6.1.2.1.2.2";
var columns = [2, 6];function sortInt (a, b) {
if (a > b)
return 1;
else if (b > a)
return -1;
else
return 0;
}
function responseCb (error, table) {
if (error) {
console.error (error.toString ());
} else {
// This code is purely used to print rows out in index order,
// ifIndex's are integers so we'll sort them numerically using
// the sortInt() function above
var indexes = [];
for (index in table)
indexes.push (parseInt (index));
indexes.sort (sortInt);
// Use the sorted indexes we've calculated to walk through each
// row in order
for (var i = 0; i < indexes.length; i++) {
// Like indexes we sort by column, so use the same trick here,
// some rows may not have the same columns as other rows, so
// we calculate this per row
var columns = [];
for (column in table[indexes[i]])
columns.push (parseInt (column));
columns.sort (sortInt);
// Print index, then each column indented under the index
console.log ("row for index = " + indexes[i]);
for (var j = 0; j < columns.length; j++) {
console.log (" column " + columns[j] + " = "
+ table[indexes[i]][columns[j]]);
}
}
}
}
var maxRepetitions = 20;
// The maxRepetitions argument is optional, and will be ignored unless using
// SNMP verison 2c
session.tableColumns (oid, columns, maxRepetitions, responseCb);
`session.trap (typeOrOid, [varbinds], [agentAddrOrOptions], callback)
The
method sends a SNMP trap.The
typeOrOid parameter can be one of two types; one of the constants
defined in the snmp.TrapType object (excluding the
snmp.TrapType.EnterpriseSpecific constant), or an OID string.For SNMP version 1 when a constant is specified the following fields are set in
the trap:
* The enterprise field is set to the OID
1.3.6.1.4.1
* The generic-trap field is set to the constant specified
* The specific-trap field is set to 0When an OID string is specified the following fields are set in the trap:
* The final decimal is stripped from the OID string and set in the
specific-trap field
* The remaining OID string is set in the enterprise field
* The generic-trap field is set to the constant
In both cases the time-stamp field in the trap PDU is set to the value
returned by the
function multiplied by 100.SNMP version 2c messages are quite different in comparison with version 1.
The version 2c trap has a much simpler format, simply a sequence of varbinds.
The first varbind to be placed in the trap message will be for the
sysUptime.0 OID (1.3.6.1.2.1.1.3.0). The value for this varbind will
be the value returned by the process.uptime () function multiplied by 100
(this can be overridden by providing upTime in the optional options
parameter, as documented below).This will be followed by a second varbind for the
OID
(1.3.6.1.6.3.1.1.4.1.0). The value for this will depend on the typeOrOid
parameter. If a constant is specified the trap OID for the constant
will be used as supplied for the varbinds value, otherwise the OID string
specified will be used as is for the value of the varbind.The optional
parameter is an array of varbinds to include in the
trap, and defaults to the empty array [].The optional
agentAddrOrOptions parameter can be one of two types; one is
the IP address used to populate the agent-addr field for SNMP version 1 type
traps, and defaults to 127.0.0.1, or an object, and can contain the
following items: *
agentAddr - IP address used to populate the agent-addr field for SNMP
version 1 type traps, and defaults to 127.0.0.1
* - Value of the sysUptime.0 OID (1.3.6.1.2.1.1.3.0) in the
trap, defaults to the value returned by the process.uptime () function
multiplied by 100NOTE When using SNMP version 2c the
agentAddr parameter is ignored if
specified since version 2c trap messages do not have an agent-addr field.The
callback function is called once the trap has been sent, or an error
occurred. The following arguments will be passed to the callback function: *
error - Instance of the Error class or a sub-class, or null if no
error occurredThe following example sends an enterprise specific trap to a remote host using
a SNMP version 1 trap, and includes the sysName (
1.3.6.1.2.1.1.5.0) varbind
in the trap. Before the trap is sent the agentAddr field is calculated using
DNS to resolve the hostname of the local host:`js
var enterpriseOid = "1.3.6.1.4.1.2000.1"; // made up, but it may be validvar varbinds = [
{
oid: "1.3.6.1.2.1.1.5.0",
type: snmp.ObjectType.OctetString,
value: "host1"
}
];
dns.lookup (os.hostname (), function (error, agentAddress) {
if (error) {
console.error (error);
} else {
// Override sysUpTime, specfiying it as 10 seconds...
var options = {agentAddr: agentAddress, upTime: 1000};
session.trap (enterpriseOid, varbinds, agentAddress,
function (error) {
if (error)
console.error (error);
});
}
});
`The following example sends a generic link-down trap to a remote host using a
SNMP version 1 trap, it does not include any varbinds or specify the
parameter:`js
session.trap (snmp.TrapType.LinkDown, function (error) {
if (error)
console.error (error);
});
`The following example sends an enterprise specific trap to a remote host using
a SNMP version 2c trap, and includes two enterprise specific varbinds:
js
var trapOid = "1.3.6.1.4.1.2000.1";var varbinds = [
{
oid: "1.3.6.1.4.1.2000.2",
type: snmp.ObjectType.OctetString,
value: "Hardware health status changed"
},
{
oid: "1.3.6.1.4.1.2000.3",
type: snmp.ObjectType.OctetString,
value: "status-error"
}
];
// version 2c should have been specified when creating the session
session.trap (trapOid, varbinds, function (error) {
if (error)
console.error (error);
});
`session.walk (oid, [maxRepetitions], feedCallback, doneCallback)
The
method fetches the value for all OIDs lexicographically following
a specified OID in the MIB tree.For SNMP version 1 repeated
get() calls are made until the end of the MIB
tree is reached. For SNMP version 2c repeated getBulk() calls are made
until the end of the MIB tree is reached.The
oid parameter is an OID string. The optional maxRepetitions parameter
is passed to getBulk() requests when SNMP version 2c is being used.This method will not call a single callback once all OID values are fetched.
Instead the
feedCallback function will be called each time a response is
received from the remote host. The following arguments will be passed to the
feedCallback function: *
varbinds - Array of varbinds, and will contain at least one varbindEach varbind must be checked for an error condition using the
snmp.isVarbindError() function when using SNMP version 2c.Once the end of the MIB tree has been reached, or an error has occurred, the
doneCallback function will be called. The following arguments will be
passed to the doneCallback function: *
error - Instance of the Error class or a sub-class, or null if no
error occurredOnce the
doneCallback function has been called the request is complete and
the feedCallback function will no longer be called.If the
feedCallback function returns a true value when called no more
get() or getBulk() method calls will be made and the doneCallback will
be called.The following example walks to the end of the MIB tree starting from the
ifTable (
1.3.6.1.2.1.2.2) OID:`js
var oid = "1.3.6.1.2.1.2.2";function doneCb (error) {
if (error)
console.error (error.toString ());
}
function feedCb (varbinds) {
for (var i = 0; i < varbinds.length; i++) {
if (snmp.isVarbindError (varbinds[i]))
console.error (snmp.varbindError (varbinds[i]));
else
console.log (varbinds[i].oid + "|" + varbinds[i].value);
}
}
var maxRepetitions = 20;
// The maxRepetitions argument is optional, and will be ignored unless using
// SNMP verison 2c
session.walk (oid, maxRepetitions, feedCb, doneCb);
`Application: Notification Receiver
RFC 3413 classifies a "Notification Receiver" SNMP application that receives
"Notification-Class" PDUs. Notifications include both SNMP traps and informs.
This library is able to receive all types of notification PDU:
*
(original v1 trap PDUs, which are now considered obselete)
* Trapv2-PDU (unacknowledged notifications)
* InformRequest-PDU (same format as Trapv2-PDU but with message acknowledgement)The library provides a
Receiver class for receiving SNMP notifications. This
module exports the createReceiver() function, which creates a new Receiver
instance.The receiver creates an
instance to control incoming access. More
detail on this is found below in the Authorizer Module section
below.snmp.createReceiver (options, callback)
The
createReceiver() function instantiates and returns an instance of the Receiver
class:js
// Default options
var options = {
port: 162,
disableAuthorization: false,
includeAuthentication: false,
accessControlModelType: snmp.AccessControlModelType.None,
engineID: "8000B98380XXXXXXXXXXXXXXXXXXXXXXXX", // where the X's are random hex digits
address: null,
transport: "udp4"
};var callback = function (error, notification) {
if ( error ) {
console.error (error);
} else {
console.log (JSON.stringify(notification, null, 2));
}
};
receiver = snmp.createReceiver (options, callback);
`The
and callback parameters are mandatory. The options parameter is
an object, possibly empty, and can contain the following fields: *
port - the port to listen for notifications on - defaults to 162. Note that binding to
port 162 on some systems requires the receiver process to be run with administrative
privilege. If this is not possible then choose a port greater than 1024.
* disableAuthorization - disables local authorization for all community-based
notifications received and for those user-based notifications received with no
message authentication or privacy (noAuthNoPriv) - defaults to false
* engineID - the engineID used for SNMPv3 communications, given as a hex string -
defaults to a system-generated engineID containing elements of random
* transport - the transport family to use - defaults to udp4
* - the IP address to bind to - default to null, which means bind to all IP
addresses
* includeAuthentication - adds the community (v1/2c) or user name (v3) information
to the notification callback - defaults to false
* - an array of objects containing triples of transport, address and port that
can be used to specify multiple socket listeners. This option overrides any individual
transport, address and port options.The
callback parameter is a callback function of the form
function (error, notification). On an error condition, the notification
parameter is set to . On successful reception of a notification, the error
parameter is set to null, and the notification parameter is set as an object
with the notification PDU details in the pdu field and the sender socket details
in the rinfo field. For example:`json
{
"pdu": {
"type": 166,
"id": 45385686,
"varbinds": [
{
"oid": "1.3.6.1.2.1.1.3.0",
"type": 67,
"value": 5
},
{
"oid": "1.3.6.1.6.3.1.1.4.1.0",
"type": 6,
"value": "1.3.6.1.6.3.1.1.5.2"
}
],
"scoped": false
},
"rinfo": {
"address": "127.0.0.1",
"family": "IPv4",
"port": 43162,
"size": 72
}
}
`receiver.getAuthorizer ()
Returns the receiver's
instance, used to control access
to the receiver. See the Authorizer section for further details.receiver.close (callback)
Closes the receiver's listening socket(s), ending the operation of the receiver. The optionnal
callback parameter is a callback function of the form function (socket), which will be
called once for each socket that the receiver is listening on, after the socket is closed.
The socket argument will be given as an object triple of address, family and port.Application: SNMP Agent
The SNMP agent responds to all four "request class" PDUs relevant to a Command Responder
application:
* GetRequest - request exactly matched OID instances
* GetNextRequest - request lexicographically "next" OID instances in the MIB tree
* GetBulkRequest - request a series of "next" OID instances in the MIB tree
* SetRequest - set values for specified OIDs
The agent sends a GetResponse PDU to all four request PDU types, in conformance with RFC 3416.
The agent - like the notification receiver - maintains an
Authorizer instance
to control access to the agent, details of which are in the Authorizer Module
section below.The central data structure that the agent maintains is a
Mib instance, the API of which is
detailed in the Mib Module section below. The agent allows the MIB to be queried
and manipulated through the API, as well as queried and manipulated through the SNMP interface with
the above four request-class PDUs.The agent also supports SNMP proxy forwarder applications with its singleton
Forwarder instance,
which is documented in the Forwarder Module section below.snmp.createAgent (options, callback, mib)
The
createAgent() function instantiates and returns an instance of the Agent
class:js
// Default options
var options = {
port: 161,
disableAuthorization: false,
accessControlModelType: snmp.AccessControlModelType.None,
engineID: "8000B98380XXXXXXXXXXXXXXXXXXXXXXXX", // where the X's are random hex digits
address: null,
transport: "udp4",
mibOptions: {}
};var callback = function (error, data) {
if ( error ) {
console.error (error);
} else {
console.log (JSON.stringify(data, null, 2));
}
};
agent = snmp.createAgent (options, callback);
`The
and callback parameters are mandatory. The options parameter is
an object, possibly empty, and can contain the following fields: *
port - the port for the agent to listen on - defaults to 161. Note that
binding to port 161 on some systems requires the receiver process to be run with
administrative privilege. If this is not possible, then choose a port greater
than 1024.
* disableAuthorization - disables local authorization for all community-based
notifications received and for those user-based notifications received with no
message authentication or privacy (noAuthNoPriv) - defaults to false
* accessControlModelType - specifies which access control model to use. Defaults
to snmp.AccessControlModelType.None, but can be set to snmp.AccessControlModelType.Simple
for further access control capabilities. See the class description
for more information.
* engineID - the engineID used for SNMPv3 communications, given as a hex string -
defaults to a system-generated engineID containing elements of random
* transport - the transport family to use - defaults to udp4
* - the IP address to bind to - default to null, which means bind to all IP
addresses
* sockets - an array of objects containing triples of transport, address and port that
can be used to specify multiple socket listeners. This option overrides any individual
transport, address and port options.
* mibOptions - a MIB options object that is passed to the Mib instance - see the MIB section
for further details on this - defaults to the empty object.The
mib parameter is optional, and sets the agent's singleton Mib instance.
If not supplied, the agent creates itself a new empty Mib singleton. If supplied,
the Mib instance needs to be created and populated as per the Mib Module
section below.agent.getAuthorizer ()
Returns the agent's singleton
Authorizer instance, used to control access
to the agent. See the Authorizer section for further details.agent.getMib ()
Returns the agent's singleton
Mib instance, which holds all of the management data
for the agent.agent.setMib (mib)
Sets the agent's singleton
Mib instance to the supplied one. The agent discards
its existing Mib instance.agent.getForwarder ()
Returns the agent's singleton
Forwarder instance, which holds a list of registered
proxies that specify context-based forwarding to remote hosts.agent.close (callback)
Closes the agent's listening socket(s), ending the operation of the agent. The optionnal
callback parameter is a callback function of the form function (socket), which will be
called once for each socket that the agent is listening on, after the socket is closed.
The socket argument will be given as an object triple of address, family and port.Authorizer Module
Both the receiver and agent maintain an singleton
Authorizer instance, which is
responsible for maintaining an authorization list of SNMP communities (for v1 and
v2c notifications) and also an authorization list of SNMP users (for v3 notifications).
These lists are used to authorize notification access to the receiver, and to store
security protocol and key settings. RFC 3414 terms the user list as the the
"usmUserTable" stored in the receiver's "Local Configuration Database".If a v1 or v2c notification is received with a community that is not in the
receiver's community authorization list, the receiver will not accept the notification,
instead returning a error of class
RequestFailedError to the supplied callback
function. Similarly, if a v3 notification is received with a user whose name is
not in the receiver's user authorization list, the receiver will return a
RequestFailedError. If the disableAuthorization option is supplied for the
receiver on start-up, then these local authorization list checks are disabled for
community notifications and noAuthNoPriv user notifications. Note that even with
this setting, the user list is still checked for authNoPriv and authPriv notifications,
as the library still requires access to the correct keys for the message authentication
and encryption operations, and these keys are stored against a user in the user
authorization list.The API allows the receiver's / agent's community authorization and user authorization lists
to be managed with adds, queries and deletes.
For an agent, there is a further optional access control check, that can limit the
access for a given community or user according to the
AccessControlModelType supplied
as an option to the agent. The default model type is snmp.AccessControlModelType.None,
which means that - after the authorization list checks described in the preceding paragraphs -
there is no further access control restrictions i.e. all requests are granted access by
the agent. A second access control model type snmp.AccessControlModelType.Simple can
be selected, which creates a SimpleAccessControlModel object that can be manipulated
to specify that a community or user has one of three levels of access to agent information:
* none
* read-only
* read-writeMore information on how to configure access with the
SimpleAccessControlModel class is
provided below under the description of that class.The authorizer instance can be obtained by using the
getAuthorizer()
call, for both the receiver and the agent. For example:js
receiver.getAuthorizer ().getCommunities ();
`authorizer.addCommunity (community)
Adds a community string to the receiver's community authorization list. Does
nothing if the community is already in the list, ensuring there is only one
occurence of any given community string in the list.
authorizer.getCommunity (community)
Returns a community string if it is stored in the receiver's community authorization
list, otherwise returns
Returns the receiver's community authorization list.
Deletes a community string from the receiver's community authorization list. Does
nothing if the community is not in the list.
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