I use Nagios to monitor almost all of our hosts and services (almost, because it's like a model railway an ever ongoing expansion passtime).
And I find that it far better suits my admin needs than so called professional suites like Tivoli (which we I regret to admit have also wasted money on).
You can indeed get prebuilt binaries for many platforms from nagiosexchange, as someone suggested.
However, these are seldomly very much up to date.
Nevertheless, the most fundamental Nagios plug-ins do compile quite easily.
If you don't have any requirement to check swap on your HP-UX hosts by the check_swap plug-in simply skip it.
It's also very easy to write your own plug-in for HP-UX swap state queries, which even would be better suited I would guess.
Either comment the target entry for check_swap in the Makefile and continue.
Or make the remaining plug-ins individually.
There is no special make install required for Nagios plug-ins.
Most of the post-compile commands involves merely things like creating symlinks to check_tcp and check_icmp (which are the two most important plug-ins, as far as the Nagios server is concerned).
If your make aborted due to the swap dificulties, I would suggest to check that check_icmp is owned by root and has the suid bit set (because only root may emit ICMP packets).
Also check that check_host is a sym or hard link to check_icmp, and define check_host as the default check command for your host checks (but *don't* define a check_interval for host checks, as it would subvert Nagios'es own scheduling of host checks and severly degrade performance!).
The check_host guise is special because it is faster than check_icmp as it would only wait for the 1st ICMP packet to return to verify an host OK state and don't linger for any other packets to return.
Is your Nagios server an HP-UX box,
or only your monitored hosts?
In the latter case you would also require some "agent" like the NRPE (also available from nagiosexchange) that would perform the check_swap on behalf of the Nagios server.
Madness, thy name is system administration
