In order to communicate with an SNMP agent such as ModSnmp, an SNMP manager will normally need to know what SNMP objects are supported by the agent. This information is usually provided to the manager as an MIB (Management Information Base) file, which lists the OID of each object, its type, and a textual name that can be used instead of the OID for referring to the object.

When you have configured ModSnmp with the devices in your system, you can generate an MIB file using the File → Generate MIB file menu item. This displays a dialog that enables you to enter or select the name of the file to which the MIB should be written.

The generated MIB file should be loaded into your SNMP manager, together with the Wingpath-MIB file, which can be downloaded from http://wingpath.co.uk/modbus/resource.php?product=modsnmp. Most SNMP managers can directly load MIB files, but some (e.g. PRTG). require the use of a separate compiler or conversion program.

MIB files are text files that can viewed using a text editor. Their format is specified in RFC 2578, and RFC 4181 contains guidelines for their contents.

The OIDs generated by ModSnmp are provided as comments in the MIB file, so you can easily copy them if you have to manually enter them into an SNMP manager.