mrtg suddenly broken

[David Bandel]

On 10/16/06, Net Llama! <netllama at linux-sxs.org> wrote:
> I've got mrtg setup on one system at home just to monitor the amount of
> traffic going over eth0 (the only NIC/interface on the system).  I set
> this up over a year ago, and its been working fine ever since.  Until
> today, when I happened to take a look at the graphs and noticed that
> they've basically flatlined.
>
> For example, I've had 25KB/s or more coming down eth0 for the past hour,
> yet the graph for the past 24hours is a huge flat line at 0KB/s except for
> a strange spike up to 4.8KB/s yesterday afternoon.
>
> The cronjob (which runs every 5 minutes) is:
> */5 * * * * root LANG=C LC_ALL=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg --lock-file /var/lock/mrtg/mrtg_l --confcache-file /var/lib/mrtg/mrtg.ok
>
> Running it manually returns no errors, but the graphs are still not
> accurate.
>
> /etc/mrtg/mrtf.cfg looks like this:
> ##############################
> WorkDir: /var/www/mrtg
> ThreshDir: /var/www/mrtg
>
> Target[r1]: 1:public at hal:
> SetEnv[r1]: MRTG_INT_IP="10.0.0.1" MRTG_INT_DESCR="eth0"
> MaxBytes[r1]: 1250000
> Title[r1]: Traffic Analysis for eth0
> PageTop[r1]: <H1>Stats for eth0</H1>
> ##############################
>
> eth0 is 10.0.0.1 on my box.
>
> I've changed nothing in the mrtg configuration, so I'm completely stumped
> on why its failing to record much of anything.  Anyone have any
> suggestions how or where to start troubleshooting this?

1.  make sure snmpd is still running on the target system

2. look in your /etc/mrtg.cfg file and note which number the interface
has.  Then do:
snmpwalk -c public -v 2c <ip_of_target> ifDesc

This will give you the descriptions of the various interfaces on your syste.

A reboot, or even loading and unloading drivers can cause a mismatch
between what mrtg is looking at and what snmp has in its table.


>
> thanks.
>

Ciao,

David A. Bandel
-- 
Focus on the dream, not the competition.
            - Nemesis Air Racing Team motto