If there is a better solution that uses established modules, I would suggest that. Barring that, here is some code I was toying with a while back to do something similar-probably not the best or most efficient way to do it, however. (Address data was in __DATA__, which I did not include here for length.) Hope maybe this might give you an idea or two (if nothing else, maybe of how not to do it). 

#!/usr/bin/perl -w

use strict;

my (%addresses);
{
    # Load data into @addresslist, 
    # ensuring only unique addresses are present
    my @addresslist = ();
    {
        my (%seen);
        while (<DATA>) {
            chomp;
            my $ip = unpack( "N", pack( "C4", split ( /\D+/, $_ ) ) );
            $seen{ $ip }++;
        }
        @addresslist = keys(%seen);
    }

    # Look thru @addresslist, 
    # storing in %addresses if there is not a key
    # where $flag <= $i <= $addresses{$flag}, or
    # incrementing $addresses{$flag} if $i == $addresses{$flag}+1
    foreach my $i (@addresslist) {
        my $flag = 0;
        foreach my $k ( sort( keys(%addresses) ) ) {
            my $target = $addresses{$k} + 1;
            if ( $i == $target ) {
                $flag = $k;
                last;
            }
        }
        if ($flag) {
            $addresses{$flag}++;
        }
        else {
            $addresses{$i} = $i;
        }
        print "\n";
    }

    # Join ranges that should have been connected, 
    # but were not because data was not seen in sequence.
    my @startvalues = sort( keys(%addresses) );
    my $i = shift (@startvalues);
    while (@startvalues) {
        my $k = shift (@startvalues);
        if ( $k == $addresses{$i} ) {
            $addresses{$i} = $addresses{$k};
            delete( $addresses{$k} );
        }
        else {
            $i = $k;
        }
    }
}

# Print address ranges on one line.
foreach my $k ( sort( keys(%addresses) ) ) {
    print join ( '.', unpack( "C4", pack( "N", $k ) ) );
    if ( $k != $addresses{$k} ) {
        print '-';
        print 
          join ( '.', unpack( "C4", pack( "N", $addresses{$k} ) ) );
    }
    print "  ";
}
print "\n";

[download]

In reply to Re: Unsorted IP Addr list to sorted IP list with ranges by atcroft
in thread Unsorted IP Addr list to sorted IP list with ranges by blue_cowdawg

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