There are lots of tools to help in this regard. One thing that needs to be understood up front is that this howto does not touch on monitoring, so as to receive notification if something is exceeding a threshold. You will want to look toward Nagios for things like that.

We will use the following tools to accomplish this task:

Much of this howto was derived from the drwindows tutorial on the Gentoo Forums. REFERENCE

root# emerge -a net-snmp

com2sec local     127.0.0.1/32  public
com2sec local     10.0.2.0/24   public

group MyROGroup v1              local
group MyROGroup v2c             local
group MyROGroup usm             local

view all    included  .1        80

access MyROGroup ""     any     noauth    exact  all    none   none

syslocation Cincinnati
syscontact John McFarlane
		

There are a few steps left to complete this step:

1. Start the Net-snmp publisher:

   root# /etc/init.d/snmpd start

2. Set Net-snmp to start on bootup:

   root# rc-update add snmpd default

3. Test to see what data is being exposed by Net-snmp:

   root# snmpwalk -v 1 -c public HOSTNAME

root# emerge -a mrtg
root# mkdir -p /etc/mrtg/devices
root# mkdir -p /etc/mrtg/graphs
		

1. Make the main MRTG configuration /etc/mrtg/mrtg.cfg look like this:

   
   WorkDir: /var/lib/mrtg
   Logdir: /var/log
   LogFormat: rrdtool
   RunAsDaemon: No
   
   LoadMIBs: /usr/share/snmp/mibs/UCD-SNMP-MIB.txt, /usr/share/snmp/mibs/TCP-MIB.txt, /usr/share/snmp/mibs/HOST-RESOURCES-MIB.txt
   				

2. Here are some tips on how to gather details you will need in the next step.

   
   root# snmptable -v 1 -c public `hostname` ifTable | cut -b-33
   				

3. Create the first device configuration /etc/mrtg/devices/HOSTNAME.inc:

   
   Target[HOSTNAME.usrsys]: ssCpuRawUser.0&ssCpuRawSystem.0:public@HOSTNAME
   MaxBytes[HOSTNAME.usrsys]: 100
   Title[HOSTNAME.usrsys]: CPU usr sys
   
   Target[HOSTNAME.idlenice]: ssCpuRawIdle.0&ssCpuRawNice.0:public@HOSTNAME
   MaxBytes[HOSTNAME.idlenice]: 100
   Title[HOSTNAME.idlenice]: CPU idle nice
   
   Target[HOSTNAME.tcpopen]: tcpCurrEstab.0&tcpCurrEstab.0:public@HOSTNAME
   MaxBytes[HOSTNAME.tcpopen]: 1000000
   Title[HOSTNAME.tcpopen]: Open TCP connections
   Options[HOSTNAME.tcpopen]: gauge
   
   Target[HOSTNAME.proc]: hrSystemProcesses.0&hrSystemProcesses.0:public@HOSTNAME
   MaxBytes[HOSTNAME.proc]: 1000
   Title[HOSTNAME.proc]: Number of running processes
   Options[HOSTNAME.proc]: gauge
   
   Target[HOSTNAME.freemem]: memTotalFree.0&memTotalFree.0:public@HOSTNAME
   MaxBytes[HOSTNAME.freemem]: 1000000
   Title[HOSTNAME.freemem]: Free Memory Total
   Options[HOSTNAME.freemem]: gauge
   
   Target[HOSTNAME.ram.swap]: memAvailReal.0&memAvailSwap.0:public@HOSTNAME
   MaxBytes[HOSTNAME.ram.swap]: 456488
   Title[HOSTNAME.ram.swap]: RAM vs swap Free Memory
   Options[HOSTNAME.ram.swap]: gauge
   
   Target[HOSTNAME.diskspercent]: .1.3.6.1.4.1.2021.9.1.9.1&.1.3.6.1.4.1.2021.9.1.9.2:public@HOSTNAME
   MaxBytes[HOSTNAME.diskspercent]: 100
   Title[HOSTNAME.diskspercent]: disk usage percent
   Options[HOSTNAME.diskspercent]: gauge,nopercent
   
   Target[HOSTNAME.disks.usage]: .1.3.6.1.4.1.2021.9.1.7.1&.1.3.6.1.4.1.2021.9.1.7.2:public@HOSTNAME
   MaxBytes1[HOSTNAME.disks.usage]: 24691824
   MaxBytes2[HOSTNAME.disks.usage]: 14048404
   Title[HOSTNAME.disks.usage]: disk available totals
   Options[HOSTNAME.disks.usage]: gauge,nopercent
   
   Target[elk.traffic]: \eth0:public@elk:
   MaxBytes[elk.traffic]: 12500000
   Title[elk.traffic]: 10.0.1.5 -- elk
   				

   Rinse and repeat for other devices you want to monitor.
   Tip

   You can monitor almost anything. You'll want to use snmpwalk to get the syntax for the Target portion of the config as it relates to the device in question.
   Here's an example of what you might use to monitor a router:

   
   Target[HOSTNAME.traffic]: 2:public@IP-ADDRESS
   MaxBytes1[HOSTNAME.traffic]: 250000
   MaxBytes2[HOSTNAME.traffic]: 125000
   Title[HOSTNAME.traffic]: Cable Modem Traffic Analysis
   				

4. Include you device config(s) into the main MRTG configuration by appending to the end of /etc/mrtg/mrtg.cfg:

   
   Include: devices/HOSTNAME.inc
   #Include: devices/foobar.inc
   				

root# echo net-analyzer/rrdtool perl > /etc/portage.package.use
		

root# emerge -a rrdtool

root# rrdtool create /var/lib/mrtg/`hostname`.disks.usage.rrd \
--start `date +"%s"` \
DS:ds0:GAUGE:600:0:24691824 \
DS:ds1:GAUGE:600:0:14048404 \
--step 300 \
RRA:AVERAGE:0.5:1:800 \
RRA:AVERAGE:0.5:6:800 \
RRA:AVERAGE:0.5:24:800 \
RRA:AVERAGE:0.5:288:800 \
RRA:MIN:0.5:1:800 \
RRA:MIN:0.5:6:800 \
RRA:MIN:0.5:24:800 \
RRA:MIN:0.5:288:800 \
RRA:MAX:0.5:1:800 \
RRA:MAX:0.5:6:800 \
RRA:MAX:0.5:24:800 \
RRA:MAX:0.5:288:800

root# rrdtool create /var/lib/mrtg/`hostname`.ram.swap.rrd \
--start `date +"%s"` \
DS:ds0:GAUGE:600:0:1034728 \
DS:ds1:GAUGE:600:0:506036 \
--step 300 \
RRA:AVERAGE:0.5:1:800 \
RRA:AVERAGE:0.5:6:800 \
RRA:AVERAGE:0.5:24:800 \
RRA:AVERAGE:0.5:288:800 \
RRA:MIN:0.5:1:800 \
RRA:MIN:0.5:6:800 \
RRA:MIN:0.5:24:800 \
RRA:MIN:0.5:288:800 \
RRA:MAX:0.5:1:800 \
RRA:MAX:0.5:6:800 \
RRA:MAX:0.5:24:800 \
RRA:MAX:0.5:288:800

root# rrdtool create /var/lib/mrtg/`hostname`.freemem.rrd \
--start `date +"%s"` \
DS:ds0:GAUGE:600:0:1034728 \
DS:ds1:GAUGE:600:0:506036 \
--step 300 \
RRA:AVERAGE:0.5:1:800 \
RRA:AVERAGE:0.5:6:800 \
RRA:AVERAGE:0.5:24:800 \
RRA:AVERAGE:0.5:288:800 \
RRA:MIN:0.5:1:800 \
RRA:MIN:0.5:6:800 \
RRA:MIN:0.5:24:800 \
RRA:MIN:0.5:288:800 \
RRA:MAX:0.5:1:800 \
RRA:MAX:0.5:6:800 \
RRA:MAX:0.5:24:800 \
RRA:MAX:0.5:288:800

root# rrdtool create /var/lib/mrtg/`hostname`.traffic.rrd \
--start `date +"%s"` \
DS:ds0:COUNTER:600:0:50000 \
DS:ds1:COUNTER:600:0:25000 \
--step 300 \
RRA:AVERAGE:0.5:1:800 \
RRA:AVERAGE:0.5:6:800 \
RRA:AVERAGE:0.5:24:800 \
RRA:AVERAGE:0.5:288:800 \
RRA:MIN:0.5:1:800 \
RRA:MIN:0.5:6:800 \
RRA:MIN:0.5:24:800 \
RRA:MIN:0.5:288:800 \
RRA:MAX:0.5:1:800 \
RRA:MAX:0.5:6:800 \
RRA:MAX:0.5:24:800 \
RRA:MAX:0.5:288:800 
		

root# mrtg /etc/mrtg/mrtg.cfg

1. CPU /etc/mrtg/graphs/HOSTNAME-cpu.bash:

   
   #!/bin/bash
   #Generates a CPU info graph
   ###########################
   
   HOST=elk
   
   case $1 in
      day)
         INTERVAL=86400;;
      week)
         INTERVAL=604800;;
      month)
         INTERVAL=2678400;;
      year)
         INTERVAL=31622400;;
      *)
         INTERVAL=86400;;
   esac
   
   if [ $INTERVAL == 86400 ]; then
      INTERVALSTR="day"
   else
      INTERVALSTR="$1"
   fi
   
   echo Generating cpu.percent.${HOST}.$INTERVALSTR.png
   echo Using $INTERVAL interval
   
   rrdtool graph /rf/blobs/rockfloat/rrdtool/cpu.percent.${HOST}.$INTERVALSTR.png \
   -s -$INTERVAL \
   -a PNG \
   -z \
   DEF:user=/var/lib/mrtg/${HOST}.usrsys.rrd:ds0:AVERAGE \
   DEF:system=/var/lib/mrtg/${HOST}.usrsys.rrd:ds1:AVERAGE \
   DEF:idle=/var/lib/mrtg/${HOST}.idlenice.rrd:ds0:AVERAGE \
   DEF:nice=/var/lib/mrtg/${HOST}.idlenice.rrd:ds1:AVERAGE \
   "CDEF:total=100,idle,-" \
   COMMENT:"                 Max        Avg     Current\n" \
   AREA:system#FF4000:"System  " \
   GPRINT:system:MAX:'%7.2lf %%' \
   GPRINT:system:AVERAGE:"%7.2lf %%" \
   GPRINT:system:LAST:"%7.2lf %%\n" \
   STACK:user#0080FF:"User    " \
   GPRINT:user:MAX:'%7.2lf %%' \
   GPRINT:user:AVERAGE:"%7.2lf %%" \
   GPRINT:user:LAST:"%7.2lf %%\n" \
   STACK:nice#00FFFF:"Nice    " \
   GPRINT:nice:MAX:'%7.2lf %%' \
   GPRINT:nice:AVERAGE:"%7.2lf %%" \
   GPRINT:nice:LAST:"%7.2lf %%\n" \
   LINE1:total#008080:"CPU     " \
   GPRINT:total:MAX:'%7.2lf %%' \
   GPRINT:total:AVERAGE:"%7.2lf %%" \
   GPRINT:total:LAST:"%7.2lf %%\n" \
   -v "%" -t "CPU usage - $INTERVALSTR" -l 0
   				

   root# chmod 755 /etc/mrtg/graphs/`hostname`.bash

#!/bin/bash

echo "The graphs are likely running now too.. give them a sec to finish"
sleep 30

cd /etc/mrtg/graphs
for file in *.bash; do
	echo 'Running ${file}...'
	./$file
	echo ''
done
		

root# chmod 755 /etc/mrtg/gen-graphs.bash
root# /etc/mrtg/gen-graphs.bash