[mrtg] Can not determine ifNumber for public at gw

[Steve Shipway]

> 2010-03-16 08:20:03: WARNING: Can not determine ifNumber for public at gw:
> ref: 'Descr'    key: 'ppp0'
...
> I did some googling and one recommendation was to simply remove the
> "ok" file.  I believe on Ubuntu the "ok" file is

Removing the OK file sometimes works (if the device has had its interfaces changed recently) but in this case it seems that MRTG is not getting all the SNMP data it expects.  The .ok file shows 'Dup' for ppp0 which means it is not a unique identifier and so cannot be used.

In your MRTG cfg file, you have a Target for the ppp0 interface.  Try using a different method to identify the interface?  Maybe because it is a ppp interface which comes and goes there are not many reliable constants.  Since you may have only one ppp interface, you might be able to use interface type.  Try '%23:community at hostname' instead (this identifies the first ppp interface).

Steve