[mrtg] Can not determine ifNumber for public at gw

[Steve Shipway]

> This was all working hunky-dory at one time, not too long ago.
> > I assume the interface actually exists at the moment?
> Yes, most definitely:
> # ifconfig ppp0
> ppp0      Link encap:Point-to-Point Protocol
>           inet addr:66.11.173.224  P-t-P:192.168.200.1 Mask:255.255.255.255
>           UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1452  Metric:1
... 
> Any other ideas?  Any other info I can gather/debug given that you know
> it's a Linux box now?

Just in case something in the kernel has gone screwy, I'd suggest rebooting to re-init the whole SNMP and network stack, and test it again.

If it's still not working, then use snmpwalk on the interface tree and see what's there - is the interface completely absent, or are some items visible?  It may be that e.g. using the IP address as identifier will work, though this may not be constant depending on your configuration.  Do this with
snmpwalk -c community hostname 1.3.6.1.2.1.2

Make sure you're on the latest MRTG (2.16.2 I think) and you've patched the OS up to date (though it could have been a recent patch that has affected the ppp handling of course).

If all this fails, and you absolutely HAVE to graph this, then you could do a workaround by getting the data via another method - eg, NRPE agent and mrtg-nrpe, or a plugin script to the SNMP daemon and check_ucd, though this is a bit messy.

Steve