How to extract IP addresses from a text file using Perl?

Question

How do I extract just the IP addresses from a text file which has an IP address per line? I would like to extract the IPs and then list the IP addresses in a separate file.

Answer 1

while(<>)
{
  print "$1\n" if /\b(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})\b/;
}

Answer 2

use Regexp::Common qw/net/;
while (<>) {
  print $1, "\n" if /($RE{net}{IPv4})/;
}