use warnings;
use strict;

my %ip_store = (
    "11.0.0.1"  => "UEH1_system_ip",
    "11.0.0.11" => "UEH11_system_ip",
    "11.0.0.3"  => "UEH25_system_ip",
    "11.0.0.25" => "UEH111_system_ip"
);

my @ip_data =
  map  { $_->[0] }
  sort { $a->[1] <=> $b->[1] }
  map  { /\.([0-9]+)$/; [ $_, $1 ] } keys %ip_store;

print $ip_store{$_}, $/, $_, $/ for @ip_data;