A SNMP message is divided into two sections: a version identifier including a community name, and a Protocol Data Unit (PDU). Version identifier and community name are used for SNMP authentication. The authentication mechanism depends on the SNMP version.
An agent uses the Trap PDU to notify a manager that an event occurred. To compose Trap PDUs, an agent sets the PDU Type to 4 (Trap), fills the Enterprise ID, the agent address, the generic as well as the
specific Trap types, and additional fields as the Timestamp fields, and the Variable Bindings.
Here is my first question: when working in SNMP v2, how does the manager know the SNMP community for reading a Trap?
My second question is: When working with SNMP v3, how is the authentication mechanism implemented within a Trap manager?
For SNMPv2C the manager just checks that the community string extracted from incoming SNMP trap/inform matches the community name configured locally for this trap originator (source).
For SNMPv3 the manager needs to know the whole bunch of security parameters like security level, username, authentication/privacy protocols and passwords, context name etc in order to authenticate incoming packet and/or even decrypt it (CBC-DES or CFB-AES) if authPriv security level is used.
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I am new to SNMP agent implementation. A confusion regarding the usage of SNMP4J API is, which SNMP4J Api should be used to create the agent? Should it be SNMP4J or SNMP4J-Agent?
An agent is some kind of server: it mainly replies to requests (it may occasionally also send traps to managers).
A manager is a some kind of client: it mainly send requests to agents (it may occasionally also receive traps from managers).
SNMP4J is the library for managers to send requests to remote agents.
SNMP4J-Agent is the library for agents to reply to requests.
So, to write a SNMP agent, you need to use SNMP4J-Agent jar file.
I've been looking around the net for a guide or tutorial on how to start on using C#.NET to query SNMP devices but I have been unsuccessful.
I am using Sharpsnmplib because of MIT license.
I didn't understand about the flow of data that how devices will communicate with SNMP agent, is there any event for which agent will listen. How devices send traps to agent and then to manager.
What is v1, v2c and v3.? Is this device configuration.
I guess I have to create some window service and periodically (timer based) execute SendTrapV1 method and in another service(SNMP manager) I have to listen to these traps.
My requirement is to identify the antenna level trap of Impinj Reader and have many SNMP devices in the network.
I have to implement also auto-discovers facility to discover SNMP devices installed in the network.
Any project or code will be helpful in this case.
In SNMP PDU , there is a field with name "community" , how community add security to snmp ? To be more specific , how a snmp agent know that, community string is correct or wrong ?
When sending SNMP traps/requests/informs, the field called community is the security that is used for "authentication". In SNMPv2 and SNMPv2C community is the only kind of security that exists. In SNMPv3, privacy and authentication passwords are way more of a good security.
The community adds security because the PDU sent keeps the community with itself. On the other side, the receiver needs to know the community (this is often done by configuration, depending on what you're using). This way, the receiver can identify that the PDU comes from a valid source because the community is the same.
I am trying to send a trap message from my agent to net-snmp but in my agent it looks like it's fine, however net-snmp doesn't show the message.
I want to know if net-snmp knows how to handle a trap message?
Normally, you would use net-snmp as an Agent.
Agents generally send traps, and don't receive them. They need to be able to handle get-requests, set-requests and get-next-requests, but not traps.
The system which receives SNMP traps is known as a Manager. Net-snmp is not an SNMP manager, but it contains all the (C) programming libraries needed for you to create your own SNMP manager, should you want to. There is also snmptrapd, which can log incoming traps into a file, or pass them to a perl script for processing.
Perhaps you're indeed asking about snmptrapd?
If traps are not logged on the receiver, normal network troubleshooting procedures apply. Snoop the traffic using Wireshark, first on the receiving system, then if needed, on the sending side. This can verify whether the traffic is dropped by the network (firewalls etc).
If you want to study the basics of the protocol, this RFC is a good starting point: "Protocol Operations for Version 2 of the Simple Network Management Protocol" http://www.ietf.org/rfc/rfc1905.txt
I'm in a process of creating security software that will address a specific type of security problem. In order to do that I would need to gather information about all the mails that are sent using Microsoft exchange. The information needed is mail's sender, receivers and timestamp. Actually I don’t even need to hold the information on real-time just counters for each sender-receiver pair for specific time frame.
How can I do that?
Is there some Exchange's service that I can use to get this information?
Must such a component be installed on each exchange server (hub, mailbox server etc')?
Are there Exchange's logs or internal database that hold such information?