System administrators lack a tool to help them spot potential attacks and stop them before it is too late and the intruder has penetrated our system. This work studies the development of an extra layer --a wrapper-- between the client and the server, which becomes a natural extension to a firewall, checking syntax and validity on each line sent to the server. Here, we do not stop at checking source and destination, but we have a system acting as an intermediary between the remote host and the server, checking each line for syntax and validity - as well as some other rules we might want to add to a specific service.