Nagvis has some issues installing with:
apt-get install nagvis

Here are the extra steps to get it running.

1). Fix the permissions outlined in the file /usr/share/doc/nagios3/README.Debian ( cat /usr/share/doc/nagios3/README.Debian will print out the contents in to the terminal).

2). Edit the backend config, in the web GUI go to Options -> Manage Backends. Then under “Edit backend” select live_1 and change the socket to: unix:/var/lib/nagios3/rw/livestatus
set a timeout to 30 (not sure if this is correct, sounded fun at the time).

3). Edit WuiViewEditMainCfg.php with the changes found here: http://sourceforge.net/p/nagvis/nagvis/ci/c7eb03fe37130546adfe298408606213f2d2fd9a/

nano /usr/share/nagvis/share/server/core/classes/WuiViewEditMainCfg.php
(instead of removing lines, I just added // as a comment).

Resources:
http://serverfault.com/questions/517362/php-error-mk-livestatus-in-nagvis
http://www.monitoring-portal.org/wbb/index.php?page=Thread&threadID=25901
https://www.mail-archive.com/[email protected]/msg1086669.html