There are lots of ways of doing that. First take a look at: this info about CIDR blocks. 

sub range_from_net {
   my ($subnet,$mask)=@_;
   my $subbits=addr2bits($subnet);
   my $maskbits=addr2bits($mask);
   my $allones = ~ $maskbits;
   my $top = $allones - 1;
   my $bottom = ($subbits + 1) & $allones;
   return ($bottom,$top);
}
sub addr2bits {
   my $ip=shift;
   my @o=split([\.],$ip);
   return ( ($o[0] << 24 ) + ($o[1] << 16) + ($o[2]<<8) + $o[3]);
}

sub bits2addr {
   my $bits=shift;
   return sprintf("%d.%d.%d.%d",
                  (($bits & 0xff000000 ) >> 24),
                  (($bits & 0x00ff0000 ) >> 16),
                  (($bits & 0x0000ff00 ) >> 8),
                   ($bits & 0x000000ff ) );
}

[download]
There may be a few bugs in the above code as I did not test it, but there is the basic overall algorithm I have used when I have had to solve the problem.

Peter L. Berghold -- Unix Professional
Peter at Berghold dot Net
   Dog trainer, dog agility exhibitor, brewer of fine Belgian style ales. Happiness is a warm, tired, contented dog curled up at your side and a good Belgian ale in your chalice.

In reply to Re: list of ips in a given subnet by blue_cowdawg
in thread list of ips in a given subnet by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.