Create SNMP Client in JAVA Using SNMP4j

There are lots of open source library for SNMP is available, even java have library for the same,  But in this article I will explain a simple example of using SNMP4j in JAVA to create a simple client which will display the hardware information.

Note : To run this program, SNMP service must be installed. Check this article to know that how to install SNMP in Windows XP.

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Create Simple NMS (Network management station / Client) in JAVA using SNMP4j:

package com.G2.SNMP.client;


import org.snmp4j.CommunityTarget;
import org.snmp4j.PDU;
import org.snmp4j.Snmp;
import org.snmp4j.Target;
import org.snmp4j.TransportMapping;
import org.snmp4j.event.ResponseEvent;
import org.snmp4j.smi.Address;
import org.snmp4j.smi.GenericAddress;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.OctetString;
import org.snmp4j.smi.VariableBinding;
import org.snmp4j.transport.DefaultUdpTransportMapping;

public class SNMPManager {

Snmp snmp = null;
String address = null;

* Constructor
* @param add
public SNMPManager(String add)
address = add;

public static void main(String[] args) throws IOException {
* Port 161 is used for Read and Other operations
* Port 162 is used for the trap generation
SNMPManager client = new SNMPManager("udp:");
* OID - . => SysDec
* OID - . => SysName
* => MIB explorer will be usefull here, as discussed in previous article
String sysDescr = client.getAsString(new OID("."));

* Start the Snmp session. If you forget the listen() method you will not
* get any answers because the communication is asynchronous
* and the listen() method listens for answers.
* @throws IOException
private void start() throws IOException {
TransportMapping transport = new DefaultUdpTransportMapping();
snmp = new Snmp(transport);
// Do not forget this line!

* Method which takes a single OID and returns the response from the agent as a String.
* @param oid
* @return
* @throws IOException
public String getAsString(OID oid) throws IOException {
ResponseEvent event = get(new OID[] { oid });
return event.getResponse().get(0).getVariable().toString();

* This method is capable of handling multiple OIDs
* @param oids
* @return
* @throws IOException
public ResponseEvent get(OID oids[]) throws IOException {
PDU pdu = new PDU();
for (OID oid : oids) {
pdu.add(new VariableBinding(oid));
ResponseEvent event = snmp.send(pdu, getTarget(), null);
if(event != null) {
return event;
throw new RuntimeException("GET timed out");

* This method returns a Target, which contains information about
* where the data should be fetched and how.
* @return
private Target getTarget() {
Address targetAddress = GenericAddress.parse(address);
CommunityTarget target = new CommunityTarget();
target.setCommunity(new OctetString("public"));
return target;



Hardware: x86 Family 6 Model 23 Stepping 10 AT/AT COMPATIBLE – Software: Windows 2000 Version 5.1 (Build 2600 Multiprocessor Free)

Explanation of every method is documented in above program. In Next article, we will write a Java Program to create SNMP Agent.


  1. hi,
    how can i can add the above snmp library to eclipse-IDE.
    I am newbie so please explain it step by step.

    1. @ aslary, select your current project, from the menu choose “Project” and opt for properties in the drop down menu. This opens a Project properties window, select the Libraries tab and click “Add external JARs” button.

      1. hi,

        Above code i have to run in my machine (ubuntuOS).following exception is comming any one help me plz iam new from this. Permission denied
        at Method)
        at org.snmp4j.transport.DefaultUdpTransportMapping.(
        at com.aurus.SnmpClient.start(
        at com.aurus.SnmpClient.(
        at com.aurus.SnmpClient.main(

        1. sorry ,above is another example code below code is this code pls help me any one..

          Exception in thread “main” org.snmp4j.MessageException: Operation not permitted
          at org.snmp4j.MessageDispatcherImpl.sendPdu(
          at org.snmp4j.Snmp.sendMessage(
          at org.snmp4j.Snmp.send(
          at org.snmp4j.Snmp.send(
          at SNMPManager.get(
          at SNMPManager.getAsString(
          at SNMPManager.main(
          Caused by: Operation not permitted
          at Method)
          at org.snmp4j.transport.DefaultUdpTransportMapping.sendMessage(
          at org.snmp4j.transport.DefaultUdpTransportMapping.sendMessage(
          at org.snmp4j.MessageDispatcherImpl.sendMessage(
          at org.snmp4j.MessageDispatcherImpl.sendPdu(
          … 6 more

  2. hi,
    i know now how to get add an external jar file
    but i get an error ->

    Exception in thread “main” java.lang.NullPointerException
    at SNMPManager.getAsString(
    at SNMPManager.main(

    69: return event.getResponse().get(0).getVariable().toString();


    1. Hi,this is kavya i have the snmp4j jars imported already still i get the error.

      Exception in thread “main” java.lang.NullPointerException
      at SNMPManager.getAsString(
      at SNMPManager.main(

  3. I am trying to iterate through a variable list of items but am not sure how to implement this, like a get next. I can iterate through my ManagedObjects that I have created with a specific OID but I want to query a group of items (slot numbers) where the base OID is the same and I want to have the query return baseOID.1, baseOID.2,…,baseOID.n

    How can I implement this in SNMP4j – any suggestions?

    1. Hi Cliff,
      You can write your own logic. Create a string which have fixed OID and then every time concatenate number and use line no 45,46 and 47 in loop. Its totally depend on your environment. Please elaborate your need if it does not fulfill answer to your query.

      Jitendra Zaa

  4. Thanks for the wonderful article. Could you please let us know the things that are required for running this program successfully…like setting params,installing variables,mibs etc.

  5. hi aslary,

    i too had a similar error , i solved it like this:

    in the line:


    actually while setting community i had given the community name as demopublic. but here it was public. so i modified the line as follows:

    target.setCommunity(new OctetString(“demopublic”));

  6. Hi RajShekhar,
    Currently i dont have the program for “snmpwalk”, if i will work or get time then definetly post here. If you will be able to resolve then please share with eceryone so that they can also get benefit.

    Jitendra Zaa

  7. great !! This api is hard to learn, do you have any idea to how change this example for snmp v3 ?

     I’m trying to make a simple GET example using test agent but it always return the same OID ( maybe its a default mib at original test package example )

    What is more strange is that no matter which ones parameters for usm i choose on client… the agent always return the same OID with an incrementing value.

  8. Hi. I have a question for you. If I would like to make a java program that will bind every 1 second a variable to a MIB oid that I’ve created (ex: form interfaces i’ve created ifATR and ifOWD) how can I do it. I would like this program just to bind the variable and every time i send a snmp request(using NETSNMP) to respond with that variable.

  9. Thanks!!

    When I tried run this code, I had the same problem that had “aslary”, but when I change the IP address from to a different one (a server IP address) it works.

    Thank you for the example.

  10. when i try to run this code its giving null pointer exception …I guess it may be due to timeout ..any help

  11. I want to run this code on a remote client I changed to when I run the program it gives me :

    Exception in thread “main” java.lang.NullPointerException
        at SNMPManager.getAsString(
        at SNMPManager.main(

    1. Hi folks, I had the same issue, and I have solved it checking that smtp service is enabled (seems that the error message cause is related with an exception that is not evaluated when the service is not enabled). Then just check that your service is enabled and well configured.

  12. After sending Get/GetNext request to devices, I closed snmp connection using “snmp.close();”. But when i used TCPView tool to check connections, I found that snmp connection still exist. How to really close snmp connection.?
    Thanks and sorry for my English!

  13. When i run this code it shows an error message:

    Exception in thread “main” java.lang.NullPointerException

    at SNMPManager.getAsString(

    at SNMPManager.main(

    can you help me please

  14. hello, I hope you can give me your opinion….
    This example could be used for a Network Monitoring System, i hope your answer, and thank you very much…

  15. Hello, i m working on a project of NMS using SNMP protocol. I will develop a android(java based) application, by which i will manage networks devices like routers,switches etc. So can you help me to this coding part of java. I will very thankful to you.

  16. HI Jitendra,
    Could you plz guide how we can load/read/compile our own mibs. i mean how to proceed with our own mibs

  17. HI Jitendra,

    The above program work well, thanks for this.
    Now I want to list all the devices details which are connected in my network, How can I do this??

  18. Hello Jitendra,
    Thanks for the example and it has been very helpful in understanding the snmp4j framework. But i wanted to ask you if this would work for an ipv6 address? if so,then what is the format for the ipv6 address scheme.?
    i tried “udp:[xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx]/161” but that doesn’t seem to be working. Can you shed some light on this?. Thanks in advance.

  19. Hi Jitendra,
    I am currently working on SNMP monitoring and for now i’m working with localhost

    I’m trying to get CPU and memory usage with SNMP. I have a Java code which takes the oid and runs the “get” command. I can reach the values with MIB-II. However when i import HOST-RESOURCES-MIB in the code i can’t get CPU information it returns Null. But some oids work properly in HOST-RESOURCES-MIB.

    For example:

    hrSystemUpTime(. gives me the value 3:51:15.07
    hrProcessorLoad(. gives me the value Null

    What is the problem?

    1. You need to change “SNMPManager” as your class name.
      For e.g
      Public class abc{}
      abc client = new abc(” “);

  20. EXCELENT my friend! thank you so much for your time writing this entry.
    I’m coding this in a spring server

  21. Windows 10
    Eclipse Helios Service Release 1
    SNMP4J 2.5.11

    Worked like a charm since first run. All I did was changing the ip to my ethernet connected DSE 892 gateway.

    SNMPManager client = new SNMPManager(“udp:”);
    SNMPManager client = new SNMPManager(“udp:”);

    Thanks for this great piece of code. Way better than a hundred tutorials.

  22. Hello
    can you help me please
    My project is about Design of an SNMP interface for remote UPS supervision with java

  23. It’s working now…can someone guide me here that how can I get a list of active interfaces from a cisco switch using this program, Is there any oid for retrieving this data from switch..Please help if someone can.. 🙂

  24. I did a loop for with 38 to 46 lineswith the idea to scan an ip range. If the UDP got a snmp device work well but if the ip is empty or without snmp device the program down with the Exception java.lang.NullPointerException. How I can capture the exception correctly and to continue the program?

  25. hi , I am facing problem to fetch the table item from snmp table(iftable ) OID (. of RFC1213.mib from TableUtils.getTable snmp4j API can you please help me regarding that and suggest how to retrieve data from snmp table??

  26. Hi , I am trying to fetch table oid data from snmp4j (TableUtils.getTable ) api but not able to get rows /Table events from it.Can you please help me???

  27. Hello sir this java Snmp version3 getbulk agent and server example.sir problem is server send the request for agent and agent accept the request.but agent can’t respond the server.please help…

  28. Getting this error on executing this code. Please help at the earliest

    Exception in thread “main” java.lang.NullPointerException: Cannot invoke “org.snmp4j.PDU.get(int)” because the return value of “org.snmp4j.event.ResponseEvent.getResponse()” is null
    at com.mycompany.happy.happymain.getAsString(
    at com.mycompany.happy.happymain.main(
    Command execution failed.

  29. Exception in thread “main” java.lang.NullPointerException: Cannot invoke “org.snmp4j.PDU.get(int)” because the return value of “org.snmp4j.event.ResponseEvent.getResponse()” is null
    at SNMPManager.getAsString(
    at SNMPManager.main(

    is this problem solved???

    Although the linux computer and the windows computer are communicating, it gives this error…

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