Open & Free Reverse Proxy Server

--redirect.sh
#!/bin/bash
#$1 = "internal" port
#$2 = IP
#$3 = port

fifoname = "revprox" + $1 #unique backpipe
nc -l $1 0<$fifoname | nc $2 $3 1>$fifoname #redirect doublepipe

--newredir.sh
#!/bin/bash
#$1 "internal" port
#$2 IP
#$3 port
#$4 lifetime (seconds)

./redirect.sh $1 $2 $3 & #run in background
pid=$! #process ID in $!

sleep $4

kill -9 $pid #kill it (-9 = extra hard)

--form.php
<form action="newredirect.php" method="POST">
The IP to forward to: <input type="text" name="IP" /><br/>
The port to forward to: <input type="text" name="port" /><br/>
<input type="submit" name="Forward" />
</form>

--newredirect.php
if( ! preg_match( '/[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}/', $_POST['IP'] ) )
    die( "Invalid IP" );

if( ! preg_match( '/[0-9]*/', $_POST['port'] ) )
    die( "Invalid port" );

if( $_POST['IP'] == "MY OWN IP" )
    die( "Not forwarding to myself" ); //dont know why, but I guess this could end "bad"

mysql_connect( ... );
mysql_select_db( "reverse_proxy" );
$res = mysql_query( "SELECT * FROM ports WHERE expires <= NOW() LIMIT 1" );
$port = mysql_fetch_object( $res );

if ( $port == null )
    die( "Sorry, no free ports. Please try again later." );

exec( "./newredir.sh " . $port->port . " " . $_POST['IP'] . " " . $_POST['port'] . "1800 &" );
mysql_query( "UPDATE ports SET expires=DATE_ADD(NOW(), INTERVAL 30 MINUTE) WHERE port = " . $port->port );

echo( "Hooray, you are now reachable at " . $_SERVER['HTTP_HOST'] . ":" . $port->port . "!" );

--ports_table.sql
CREATE TABLE IF NOT EXISTS `ports` (
  `port` int(11) NOT NULL,
  `expires` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`port`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;