use Modern::Perl;
use Text::CSV_XS;
use Data::Dump qw/dump/;

my $csv = Text::CSV_XS->new( { sep_char => ';' } );

my %data;
while (<DATA>) {
    $csv->parse($_) or die 'Error in parsing';
    my @columns = $csv->fields();
    push @{ $data{ $columns[0] }{'members'} },
      {
        'name'  => $columns[1],
        'email' => $columns[3],
        'ip'    => $columns[4],
      };
    $data{ $columns[0] }{'alias'} = $columns[2];
}

say dump(%data);

__DATA__
"GSBDTD1831";"nbSm3Bh";"App.-Server MAIN";"user@example.com";"10.100.0.2"
"GSBTD1832";"nbSm3haz";"Appl.-Server Aux";"user1@example.com";"10.100.0.3"
"GSTD1822";"denJdkep64";"Printserver";"user3@example.com";"192.168.91.1"
"GSTD1822";"denJdw0a22";"Printserver";"user4@example.com";"192.168.91.2"
"GSTD1822";"nbSwgP14a";"Printserver";"user5@example.com";"192.168.91.5"
"GSTD1983";"nbgwgxOrO";"Server2";"user5@example.com";"10.1.1.22"