After a three year stint with VoIP operations we're back to focusing on netflow-based monitoring.

So, the first thing I noticed is that recent versions of Perl have affected the operation of FlowViewer. Version 5.26 in particular has eliminated the current directory (.) from the default @INC array. FlowViewer depended on this to provide access to the common modules, FlowViewer_Configuration.pm, FlowViewer_Utilities.pm and FlowViewer_UI.pm. FlowViewer installations using Perl v 5.26 or later will simply fail (e.g., see /var/log/apache2/error.log). There is a simple fix which requires moving those common files into an acceptable, secure, directory already available to @INC. Such directories can be found from the command prompt like this:

flowviewer@whiterose1:/var/www/cgi-bin/FlowViewer_4.6$ perl -V
@INC:
/etc/perl
/usr/local/lib/x86_64-linux-gnu/perl/5.26.1
/usr/local/share/perl/5.26.1
/usr/lib/x86_64-linux-gnu/perl5/5.26
/usr/share/perl5
/usr/lib/x86_64-linux-gnu/perl/5.26
/usr/share/perl/5.26
/usr/local/lib/site_perl
/usr/lib/x86_64-linux-gnu/perl-base

I have moved the common files mentioned above into /usr/share/perl5 and created softlinks in the main CGI directory to point to them like this:
lrwxrwxrwx 1 flowviewer flowviewer 44 Oct 19 17:16 FlowViewer_Configuration.pm -> /usr/share/perl5/FlowViewer_Configuration.pm*
lrwxrwxrwx 1 flowviewer flowviewer 33 Oct 19 17:17 FlowViewer_UI.pm -> /usr/share/perl5/FlowViewer_UI.pm*
lrwxrwxrwx 1 flowviewer flowviewer 40 Oct 19 17:16 FlowViewer_Utilities.pm -> /usr/share/perl5/FlowViewer_Utilities.pm*