ELSA Cable manual Accessing tables and parameters using Snmp, Access protection in Snmp

Configuration modes 25

SNMP V.1 has only a very limited set of commands at its disposal, as the table below shows:

Command	Target/Source	Function
GetRequest	Manager – Agent	retrieves information from the agent
GetNextRequest	Manager – Agent	retrieves the information contained in
		the following MIB from the agent
SetRequest	Manager – Agent	modifies a setting in the agent
GetResponse	Agent – Manager	returns the queried value to the man-
		ager
Trap	Agent – Manager	reports on an error or special status

These commands can be used for central monitoring and configuration of SNMP-capable devices on a network. The SNMP capabilities of the agents are specified in so-called MIBs = Management Information Bases.

The firmware of ELSA routers includes an implementation for an SNMP V.1 agent (in accordance with RFC 1157). A part of MIB-2 and a private MIB, included in the product as a separate file, are supported. This MIB must be loaded and translated by an SNMP manager (HP OpenView, for example) to allow you to manage a device completely using SNMP. All menus and parameters of the remote configuration will then be available to you on a single branch of the SNMP management tree:

Accessing tables and parameters using SNMP

Any of the tables and parameters can be read and modified as necessary via the SNMP interface. This also involves specifying in the MIB the variables which should have 'read- only' or 'read-write' status. Commercially available SNMP managers indicate 'read-only' and 'read-write' status using color coding.

Access protection in SNMP V.1

Access to SNMP objects is controlled using so-called communities. A community is basically a password used to govern access to particular classes of information. The router permits read-only access to all parameters and tables through the 'public' community. Bear in mind that this community cannot execute any write accesses.

You must use the device's password if you wish to write data using SNMP. Write access using SNMP will not be granted as a matter of principle if the device's password is not entered.

If the trapping mechanism is enabled and a failed access attempt is detected, an 'Authentication Failed' trap is triggered and sent to the manager(s) in the SNMP trap table.

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