use strict;
use Data::Dumper;

my %hosts;
while (<DATA>) {
  next if /^\s*(?:#|$)/;  # ignore comments and empty lines
  /^([^\s#]+)\s+(.*)/;    # capture ip address and names
  $hosts{$_} = $1 foreach split /\s+/, $2;
}

print Dumper(\%hosts);

__DATA__
# IP Masq gateway:
192.168.0.80    pedestrian

# Primary desktop:
192.168.0.82    raptor1

# Family PC upstairs:
192.168.0.84    trex tyrannosaur family

# Domain servers:
205.212.123.10  dns1 brutus
208.140.2.15    dns2
156.63.130.100  dns3 cherokee