SNMP (Simple Network Management Protocol) was developed so the manager could reach out across the network to manage not only servers, but also the physical devices such as routers, bridges, Ethernet hubs, Token Ring MAUs and etc.. There are two main pieces to SNMP, the SNMP Managers and the SNMP Agents. SNMP is a very simple protocol. It uses UDP packets (on port 161) to send and receive the information sent back and forth between the Management software and the SNMP Agent.
SNMP Managers are stations that have SNMP management software installed. The management software handles querying the devices that it manages and also looks for alert conditions on the network.
SNMP Agents is the part of the protocol that sits in the devices and responds to the requests of the Management software. The Agent is also responsible for sending alerts to the Managers on the network.
There are four commands in the SNMP protocol:
The data structure used by SNMP protocol is the MIB. This enables a SNMP Agent to return values to a Manager or to set values that it receives from the Manager. MIBs are broken down very similar to DNS. There is a root to the MIBs, and then you go down a level and there are a few branches, until you get to the MIBs that deal with the Internet (see p 481, figure 17.1 ).
NT supports four MIBs.
Communities set the security of SNMP protocol. The SNMP Agent will only respond to another system within its own community. A community name identifies a group of systems managed as one unit. The Management stations and the Agents must share the same community name before they can communicate.
Another method of security with this protocol is to set a filter on UDP port 161 at the router. To be able to manage the network across the Internet, you would need to use PPTP (Point-to-Point-Tunneling-Protocol). As you will recall, PPTP uses tunneling to enable packets for one protocol to be carried over networks running another protocol. (A PPTP tunnel between 2 nodes establishes a secure communication channel between them). Microsoft refers to PPTP tunneling as a VPN (Virtual Private Networks).
To enable PPTP filtering:
And lastly, you can to Agent software to which Management systems it can respond. This keeps internal hackers from taking over workstation management.
To install SNMP Service go into services tab, choose SNMP Agent, restart (see page 484 for configuring SNMP Agent)
There are 3 tabs on SNMP properties
Agent tab includes the following services:
Traps tab
Sets the destination of where the Traps are to be sent to. (because a single host might be a member of more than one community, Trap destinations can be set for each community.
Security tab
Here you establish the community name or names that this system will be a part of. It also enables you to set authentication Traps and the Managers that you should respond to.
the SNMPUTIL (NT 4 Resource Kit) is used to test SNMP. (see page 487, figure 17.7) One SNMP Maganer is HP's Openview.
syntax is snmputil command IP_address community_name object_ID
three commands are:
The SNMP Agent must be installed for the TCP/IP counters in PefMon to be installed. The various Counters added to PerfMon when SNMP Agent is installed.
Performance Monitor is a tool for checking the performance of you system.
There are four views to PerfMon.
The chart view enables you to monitor real-time activity on the computer. Very good for watching current data. You can add counters by Edit-->Add to chart.
The Log view is used to view the activity over a longer period of time. You need to create a log file that contains the counters for all instances of the objects that you select. Once this is collected you can view this information in either Chart view or the Report view.