Moreover, the webpage displays the location of this object under the MIB tree. Soon we get the answer: The OID is 1.3.6.1.2.1.1.4, and we can read other information also. Let’s try it: Locate the “Enter OID or object name field,” enter sysContact, and then click on Translate.
But where do we know the OID from? Cisco has a useful webpage called SNMP Object Navigator, which can be found here:
Another method: If we already know the OID, we can click on Add, enter the OID value, and then query it. The program displays the OID select it and click the Query button. Find the desired value in the MIB tree on the right (for example, the sysName), right-click, on it and select Query. We can query values nearly the same way as we did with the MIB Browser. By right-clicking on a message and choosing Info, we can read the details of the message. The program automatically watches for traps, so if we generate some events again (turn Loopback1 up, for example), this immediately appears in the bottom, under the Traps tab.
After the software finds our router, select and add it to the list of the SNMP agents: Now enter the address of the R1 router into the Address field and click on Find. Click on Properties, fill in the Community, and choose version 2. Say “yes,” and the Discover SNMP Agents window appears. The first time it runs, the software asks if we want to discover available agents.
Stop the TrapViewer, close the MIB browser, and start PowerSNMP Free Manager. Let’s use another program that can be useful to experiment with. The window that appears gives us more information, the most important one in the Message field: We can read that Loopback1 went down administratively. This output is not very useful, though, so select, for example, the last row and then click on the Show Details button. We can see the usual syslog messages on the console, and the debug messages also state that the SNMP messages are queued to send:Īfter some time, we can see the trap messages appearing in the TrapViewer window: One of the simplest ways to achieve this to enable an interface, so let’s create a loopback interface (for example Loopback1) and, after it comes up, shut it down. It’s time to generate some events that trigger trap messages. This can be important if we use a firewall and don’t want to block the trap messages): Enter the community string “testing” into the Community field, then click on the Start button (notice the port number also: SNMP trap service uses UDP port 162. In the Edit/Settings menu, choose v2c version, then go to the View menu and start Trap Viewer (or press ALT-P). Now on the NMS (the XP machine in the lab), launch the ManageEngine MIB Browser.
Moreover, we can use the debug service to check if the router really sends those messages. Then we need to tell which host will receive the traps, what version we will use, and how we can authenticate ourselves to that host (now we use the community string for this purpose). On the router, we need to enable the sending of traps, as it is disabled by default.
Click here to download GNS3 files for this lab