You are talking about a hash of arrays in your original question, but it looks like you really want an array of arrays... Is this correct?

In your code you have the following:

push (@{%newhash->{$rows[0]}}, @newrows);
push (@{%newhash->{$rows[0]}}, @newrows);
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We can simplify this to the following since $rows[0] = 'IP' and does not change (Do you maybe want a real IP address here?):

push @{$newhash{IP}}, @newrows);
push @{$newhash{IP}}, @newrows);
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Which is essentially saying that you want to treat the value at $newhash{IP} as an array reference, and you want to push the values in @newrows onto the end that array.

If you want this to be a two dimensional array, then you need to take Paladin's advice and push a reference to the array instead of pushing the values of the array.

push @{$newhash{IP}}, [@newrows]);
push @{$newhash{IP}}, [@newrows]);
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That will make copies of the array, and push a reference to the new array (you could also use \@newrows). Using Data::Dumper, the above will show up as:

$VAR1 = {
          'IP' => [
                    [
                      'value1',
                      'value2'
                    ],
                    [
                      'value1',
                      'value2'
                    ]
                  ]
        };
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Is this what you are after?

Now the loop at the end where you are trying to read the values will require some changes as well:

@printrows = $newhash{$key}; # wrong -> the hash will contain a refere
+nce to an array
@printrows = @{$newhash{$key}}; # right -> de-reference the array firs
+t
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- Cees