If you want to protect the data on your computer and control who can access it, you should use a firewall. There are lots of different firewalls that you can use, and they are easy to implement and customize to suit your wants, needs, and expectations in terms of this kind of security measure, so I recommend that you research a few different ones on the web and see which of them is the best match for what you want in a firewall. There are a few different kinds of firewall techniques – you can use one that implements packet filtering, which inspects all the packets of info that try to come in to your computer. It can be difficult to configure packet filtering, but it is quite effective, and most users can’t even tell it is there. Be wary, though; it can be susceptible to hackers who “spoof” their IP, or forge it. If you use a firewall that implements an application gateway, it can apply security measures to specific programs like an FTP app, or Telnet. Although this kind of computer security is effective, it can degrade performance on your computer. Circuit level gateways apply security measures when a connection is made with your computer, but once the connection is established, data flows freely. If you use a proxy server style firewall, you can intercept all messages entering and leaving your network, and maintain security and privacy for your computers – using a proxy server allows you to hide the true network addresses of everything behind it! There are lots of thieves and internet vandals out there who would do harm to your networks if they could get at it, so make sure to protect your valuable equipment and data by using a good firewall program. You can find out more about different kinds of firewalls on the internet. Make sure to educate yourself about your options in terms of this kind of on line security so that you pick the one that is the best match for you and your network.