I do
this by using the NRPE agent on the UNIX hosts. Then you can use standard
plugins, and if NRPE is kicked off by xinetd you can also tie it down to the IP
address of your Nagios server, for extra security.
Other
possibilities include using SNMP (depends on the quality of your agent, but
NET_SNMP could do it) and using ssh checks (which would require a login shell
and ssh keys, a nuisance to maintain).
Steve
