The Dude is an awesome free monitoring tool.
Recently my Dude server crashed and I had to re install it and restore the config from backup. All went well, except all the Interfaces monitored with SNMP showed the following error: invalid oid
Follow these steps to fix the problem:
1. From the tree menu on the left, click on Mib Nodes
2. Then click on File from the top tabs
3. Click the red + button to add new MIBs
4. Browse to where you installed the dude and look for the Data\files\mibs folder (default to c:\Program Files\Dude\)
5. Add at least mikrotik.txt and SNMPv2-*.txt