Just another way of iterating on a deeply nested hash which does not need to go back to the original hash each time (a made up example)

use strict;
use warnings;
use Data::Dumper;


my %hash;
my $count = 0;

# populating a deeply nested hash
for my $ip (qw <ip1 ip2 ip3>) {
    for my $port ( qw <port1 port2 port3>) {
        for my $status (qw <stat1 stat2>) {
            for my $user (qw <user1 user2 user3>) {
                $hash{$ip}{$port}{$status}{$user} = $count++;  # (just
+ a dummy value for testing)
            }
        }
    }
}

# print Dumper \%hash;

# iterating through the nested hash
for my $nest0 (values %hash) {
    while (my ($port, $nest1) = each %$nest0) {        
        while (my ($status, $nest2) = each %$nest1) {
            for my $freq (values %$nest2) {
                print "$port\t$status\t$freq\n";
            }
        }
    }
}
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Note: I use each when I need both the key and the sub-hash ref (because I need to print the key) and values when I only need to dive one step further into the nested structure. But, for some reason, a for loop with each seems to behave inconsistently (incomplete results) on my Perl version, so I used a while loop for the cases with each. I think to remember from the past there was a bug at some point on each, maybe my version of Perl is one of them. Well, anyway, replacing the for loop by a while loop solves the issue.

This prints in part:

port2   stat2   9
port2   stat2   11
port2   stat2   10
port2   stat1   6
port2   stat1   8
port2   stat1   7
port3   stat2   15
port3   stat2   17
port3   stat2   16
port3   stat1   12
port3   stat1   14
port3   stat1   13
port1   stat2   3
port1   stat2   5
port1   stat2   4
port1   stat1   0
port1   stat1   2
.....
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