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mrtg-logfile - description of the mrtg-2 logfile format


This document provides a description of the contents of the mrtg-2 logfile.


The logfile consists of two main sections.

It stores the traffic counters from the most recent run of mrtg.
Stores past traffic rate averages and maximum at increasing intervals.

The first number on each line is a unix time stamp. It represents the number of seconds since 1970.


The first Line

The first line has 3 numbers which are:

A timestamp of when MRTG last ran for this interface. The timestamp is the number of non-skip seconds passed since the standard UNIX "epoch" of midnight on 1st of January 1970 GMT.
The "incoming bytes counter" value.
The "outgoing bytes counter" value.

The rest of the File

The second and remaining lines of the file contains 5 numbers which are:

The Unix timestamp for the point in time the data on this line is relevant. Note that the interval between timestamps increases as you progress through the file. At first it is 5 minutes and at the end it is one day between two lines.

This timestamp may be converted in OpenOffice Calc or MS Excel by using the following formula


(instead of ";" it may be that you have to use "," this depends on the context and your locale settings)

you can also ask perl to help by typing

 perl -e 'print scalar localtime(x),"\n"'

x is the unix timestamp and y is the offset in seconds from UTC. (Perl knows y).

The average incoming transfer rate in bytes per second. This is valid for the time between the A value of the current line and the A value of the previous line.
The average outgoing transfer rate in bytes per second since the previous measurement.
The maximum incoming transfer rate in bytes per second for the current interval. This is calculated from all the updates which have occurred in the current interval. If the current interval is 1 hour, and updates have occurred every 5 minutes, it will be the biggest 5 minute transfer rate seen during the hour.
The maximum outgoing transfer rate in bytes per second for the current interval.


Butch Kemper <> and Tobias Oetiker <>

2022-01-19 2.17.10