#!/usr/bin/perl -w
###
# scan a range of ports on a given machine
# see Cookbook, pg 604, chap 17
# 
# see Net::Telnet (chap 18, Cookbook), for a telnet read/write by 
# port interface.
#
# also see /etc/inet/services (or /etc/services)
#
#####

use IO::Socket;
$remote_host = "big.marlboro.edu";
$start_port=0;
$stop_port=512;

#######
# One approach is to 
# find all the ports listed in /etc/inet/protocols.
# each line is 
#     protocol port/type ...
# where type is "tcp" or "udp"
#
# I'm doing something simpler right now, namely
# just trying all ports from 0 to 512 (arbitrarily, as an example).
########
@open=();
@skipped=();
for ($remote_port=$start_port; $remote_port<$stop_port+1; $remote_port++) {

# current version gets stuck on these (Timeout doesn't seem to fix?)
my $problems = ",9,23,111,512,";
push(@skipped, $remote_port), next if $problems =~ m/,$remote_port,/;

#  9  - ?
# 23  - telnet/tcp
# 111 - sunrpc/udp
# 512 - ?

print "---",$remote_port,"---:\n";

  $socket = IO::Socket::INET->new(PeerAddr => $remote_host,
				  PeerPort => $remote_port,
				  Type     => SOCK_STREAM, 
				  Timeout  => 1,
				 );
#### don't want to report lots of errors; many will fail.
#    or die "Couldn't connect to $remote_host:$remote_port : $@\n";

  if (defined $socket) {
    print "opened port $remote_port : ";
    push @open, $remote_port;
    # ... do something with the socket
    print $socket "test foo \n\n\n";
    $answer = <$socket>;
    if (defined $answer) {
      print "returned '$answer' ; \n"; }
    else { 
      print "nothing returned \n"; }

  # and terminate the connection when we're done
    close($socket);
  }

}

print "========\n";
print "  ports that tested open from $start_port->$stop_port : @open \n";
print "  ports skipped: @skipped \n";