Nagios for Debian
Nagios is a robust and scalable host/service/network monitoring system. It is capabable of remotely monitoring large numbers of devices/hosts simultaneously, has an extensible plugin-based architecture, a notification framework, a web-based interface, and more.
Nagios is currently used to be maintained by the Debian Nagios Maintainer Group.
Nagios3 is currently maintained in git:
git clone git+ssh://git.debian.org/git/pkg-nagios/pkg-nagios3.git
The repository uses a debian/-only layout which is not supported well by git-buildpackage. Therefore, Alexander has built a wrapper to build the package which is available at http://git.snow-crash.org/?p=git-bp.git;a=summary
Please note that due to Alioth limitations, the SCM web page on the Alioth Project points to an empty repository. The svn repository is still active, but not used any more. Any commits done there will be ignored.
Once installed, you should use the command 'htpasswd' to create file '/etc/nagios3/htpasswd.users' and set a password on the user 'nagiosadmin' (or edit /etc/nagios3/cgi.cfg to add some users and set passwords on those, then do 'service nagios3 reload'). Once that is done you may review 'http://localhost/nagios3/' to see what is up in Nagios and view the docs.