#install lm-sensors
apt-get install lm-sensors

sensors-detect
# follow questions
/etc/init.d/module-init-tools restart
#check
sensors

#install munin on server
apt-get install munin

#install munin on client(s)
apt-get install munin-node

ln -s /usr/share/munin/plugins/sensors_ /etc/munin/plugins/sensors_fan
ln -s /usr/share/munin/plugins/sensors_ /etc/munin/plugins/sensors_temp
ln -s /usr/share/munin/plugins/sensors_ /etc/munin/plugins/sensors_volt

echo "allow ^ip\.address\.of\.server$" >> /etc/munin/munin-node.conf

/etc/init.d/munin-node restart

#if this errors shows in the logfile
#Can't locate Net/SNMP.pm in @INC (@INC contains: [blah]
#then you are quit possibly missing some necessary perl stuff, 
#I'm sure this will fix that:
apt-get install libnet-snmp-perl

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http://waste.mandragor.org/munin_tutorial/munin.html