Nagios
Nagios is a powerful monitoring system that enables organizations to identify and resolve IT infrastructure problems before they affect critical business processes.
Check command
/usr/local/nagios/libexec/check_nrpe -H 192.168.1.1 -c check_metric
Sample /etc/nagios/nrpe config file on CentOS 6.3 64 bit, host checked by Nagios
log_facility=daemon pid_file=/var/run/nrpe/nrpe.pid server_port=5666 nrpe_user=nrpe nrpe_group=nrpe #nagios server 192.168.1.2 allowed_hosts=196.168.1.2,127.0.0.1 dont_blame_nrpe=0 debug=1 command_timeout=60 connection_timeout=300 include_dir=/etc/nrpe.d/ command[check_users]=/usr/lib64/nagios/plugins/check_users -w 5 -c 10 command[check_load]=/usr/lib64/nagios/plugins/check_load -w 15,10,5 -c 30,25,20 command[check_hda1]=/usr/lib64/nagios/plugins/check_disk -w 20% -c 10% -p /dev/hda1 command[check_zombie_procs]=/usr/lib64/nagios/plugins/check_procs -w 5 -c 10 -s Z command[check_total_procs]=/usr/lib64/nagios/plugins/check_procs -w 150 -c 200