http_proxy()
  HTTP proxy service (experimental).
  
  !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
  !!!  WARNING! This service is experimental! Use at your risk!  !!!
  !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
  
  This service can be used as filtering HTTP proxy.
  
  Usage: http_proxy(scanners, host, port, prefork=2)
  
  Where: scanners is an array of scanners (see README.scanners for more info)
         host is a an ip address to bind
         port is a port to bind
         prefork is a number, which defines preforked process count
  
  Example: http_proxy(SCANNERS, '127.0.0.1', 3128)
  
  Warning! Do not forget to block access to this port for non-local users.