SNMP agent configuration windows/linux

i need to retrieve information via snmp and then use this information to create some sort of graphic application in Unity.

I find the SnmpSharp library http://www.snmpsharpnet.com/

i create a little program in unity using this library and then i installed the snmp on my windows machine(using windows official guide) , on localhost it works!

Now my problem is how can i connect to other agent on my lan network ? How can install agent on my other device example a linux pc ? i'm a little confused beacuse i try to install snmp on an other windows pc but i can't retrieve snmp information from it ; i try to install the snmp agent on a linux pc but i don't understand how to correctly install an agent that have to communicate across my lan

This is the code that work on localhost

using UnityEngine;
using UnityEngine.UI;
using System.Collections;
using SnmpSharpNet;
using System.Net;


public class SNMP_walk : MonoBehaviour {

[SerializeField] public InputField community_str;
[SerializeField] public InputField agent_ip_address;
[SerializeField] public Button MyButton ;
string str_community  = null;
string ip  = null;
void Start () {
    //test button

    MyButton.onClick.AddListener (() => {
        str_community = community_str.text; 
        ip = agent_ip_address.text;
        Debug.Log (str_community);
        Debug.Log(ip);
        snmp_walk (str_community, ip);
    });
}

// Update is called once per frame
void Update () {

}

void snmp_walk(string str_community, string ip){

    OctetString community = new OctetString (str_community);
    // Define agent parameters class
    AgentParameters param = new AgentParameters (community);
    // Set SNMP version to 1 (or 2)
    // settare in base alla versione usata
    param.Version = SnmpVersion.Ver1;
    // Construct the agent address object
    // IpAddress class is easy to use here because
    //  it will try to resolve constructor parameter if it doesn't *
    //  parse to an IP address
    IpAddress agent = new IpAddress (ip);

    // Construct target
    // IP, port,timeout,retry
    UdpTarget target = new UdpTarget ((IPAddress)agent, 161, 4000, 2);
    //necessario per tutte le richieste
    Pdu pdu = new Pdu (PduType.Get);

    pdu.VbList.Add ("1.3.6.1.2.1.1.1.0"); //sysDescr
    pdu.VbList.Add("1.3.6.1.2.1.1.2.0"); //sysObjectID
    pdu.VbList.Add("1.3.6.1.2.1.1.3.0"); //sysUpTime
    pdu.VbList.Add("1.3.6.1.2.1.1.4.0"); //sysContact
    pdu.VbList.Add("1.3.6.1.2.1.1.5.0"); //sysName
    pdu.VbList.Add ("1.3.6.1.2.1.25.2.2.0"); //Load for one core
    //pdu.VbList.Add ("1.3.6.1.2.1.25.6.3.1.1.11"); //Memory ? occupata
    //pdu.VbList.Add ("1.3.6.1.2.1.25.3.3.1.2.4"); //CPU ?

    SnmpV1Packet result = (SnmpV1Packet)target.Request (pdu, param);


    // If result is null then agent didn't reply or we couldn't parse the reply.
    if (result != null) {
        // ErrorStatus other then 0 is an error returned by 
        // the Agent - see SnmpConstants for error definitions
        if (result.Pdu.ErrorStatus != 0) {
            // agent reported an error with the request
            Debug.Log ("Error in SNMP reply. Error {"+result.Pdu.ErrorStatus+"} " +
                       "index {"+result.Pdu.ErrorIndex+"}");

        } else {
            // Reply variables are returned in the same order as they were added
            //  to the VbList
            Debug.Log ("sysDescr({"+result.Pdu.VbList [0].Oid.ToString ()+"}) " +
                "({"+SnmpConstants.GetTypeName (result.Pdu.VbList [0].Value.Type)+"}): " +
                "{"+result.Pdu.VbList [0].Value.ToString ()+"}"); 


            Debug.Log("sysObjectID({"+result.Pdu.VbList [1].Oid.ToString ()+"}) " +
                      "({"+SnmpConstants.GetTypeName (result.Pdu.VbList [1].Value.Type)+"}): " +
                      "{"+result.Pdu.VbList [1].Value.ToString ()+"}"); 

            Debug.Log("sysUpTime(({"+result.Pdu.VbList [2].Oid.ToString ()+"}) " +
                      "({"+SnmpConstants.GetTypeName (result.Pdu.VbList [2].Value.Type)+"}): " +
                      "{"+result.Pdu.VbList [2].Value.ToString ()+"}"); 

            Debug.Log("sysContact(({"+result.Pdu.VbList [3].Oid.ToString ()+"}) " +
                      "({"+SnmpConstants.GetTypeName (result.Pdu.VbList [3].Value.Type)+"}): " +
                      "{"+result.Pdu.VbList [3].Value.ToString ()+"}"); 

            Debug.Log("sysName(({"+result.Pdu.VbList [4].Oid.ToString ()+"}) " +
                      "({"+SnmpConstants.GetTypeName (result.Pdu.VbList [4].Value.Type)+"}): " +
                      "{"+result.Pdu.VbList [4].Value.ToString ()+"}"); 

            Debug.Log("Total Mem ({"+result.Pdu.VbList [5].Oid.ToString ()+"}) " +
                      "({"+SnmpConstants.GetTypeName (result.Pdu.VbList [5].Value.Type)+"}): " +
                      "{"+result.Pdu.VbList [5].Value.ToString ()+"}"); 

        /*  Debug.Log("CPU ? " + result.Pdu.VbList[6].Oid.ToString()+
                      SnmpConstants.GetTypeName(result.Pdu.VbList[6].Value.Type)+
                      result.Pdu.VbList[6].Value.ToString());*/

        }
    } else {
        Debug.Log ("No response received from SNMP agent.");
    }
    target.Close ();
}

}

Thanks for your help and sorry for my english !

Solution

By default, once installed, SNMP Agent on Windows only allows queries from localhost.

To allow remote SNMP queries, you need to setup the SNMP Service :

Open Windows Services Manager
Right Click on SNMP Service and edit Properties
Select Security tab

enter image description here

From here, add remote host(s) allowed to query your SNMP Agent.

Edit:

I am aware that this could just answer a part of your question : Cannot query Windows SNMP Agent from hosts other than localhost.

How to install/configure SNMP Agent on Linux would be a full other question, describing what you have tried and what is not working.

C# code review/debug shoud be posted on SF sister site : stackoverflow