Using the SNMP plugin

In OpenAF there are two main SNMP plugins: SNMP and SNMP server. In this article we are going to focus on the SNMP plugin that provide SNMP client functionality.

SNMP has different versions (e.g. 1, 2, 3) that require different settings. Starting with version 1 and 2 all you need is the SNMP connection details and, optinionally, a community:

plugin("SNMP");
var snmp = new SNMP("udp:snmpsim.try.thola.io/161", "public");  // version 1/2

Checking an OID value

To get the value associated with an OID:

snmp.get("1.3.6.1.2.1.1.3.0");
// {
//  "1.3.6.1.2.1.1.3.0": "36 days, 12:34:56.51"
//}

Sending a trap/inform

To send a trap simply:

snmp.trap("1.3.6.1.4.1.20408.4.1.1.2", [
    { OID: "1.2.3.4.5.6.7.8", type: "s", value: "My error message." }
])

You just need to provide the trap OID and an array of OID based values. Each value can have a different type. The supported types are:

Type	Description
i	Integer
u	Unsigned
c	Counter32
s	String
x	Hex String
d	Decimal String
n	A null object
o	An object id
t	Timeticks
a	An ip address

To inform it’s exactly the same but it will return you a Java response object:

var response = snmp.inform("1.3.6.1.4.1.20408.4.1.1.2", [
    { OID: "1.2.3.4.5.6.7.8", type: "s", value: "My error message." }
])

In contrast sending a trap will return immediately and there won’t be any acknowledgement.

Note: Do keep in mind that the value map entry is expected to correspond to the type provided on the same map entry. For example, adding a integer value in contrast with the string value:

snmp.trap("1.3.6.1.4.1.20408.4.1.1.2", [
    { OID: "1.2.3.4.5.6.7.8", type: "s", value: "My error message." },
    { OID: "1.2.3.4.5.6.7.9", type: "i", value: 123 }
])

Version 3

On version 3 you need to provide a little more information:

plugin("SNMP");
var aTimeout = 3000, aNumberOfRetries = 3;
var snmp = new SNMP("udp:snmpsim.try.thola.io/161", "public", aTimeout, aNumberOfRetries, 3, {
    engineId      : "8000002a000000000001020304",
    authPassphrase: "authkey1",
    privPassphrase: "privkey1",
    authProtocol  : "MD5",
    privProtocol  : "DES",
    securityName  : "usr-md5-des"
})

But all the rest is same as shown previously.

The following tables list the possible authProtocol and privProtocol values.

authProtocol values

Possible values:

authProtocol
HMAC128SHA224
HMAC192SHA256
HMAC256SHA384
HMAC384SHA512
MD5
SHA

privProtocol values

Possible values:

privProtocol
3DES
AES128
AES192
AES256
DES