A firewall is a security device that resides between the internet and your computer. Many hardware firewall products such as SDProxy.
Firewalls can also keep a log of traffic for auditing purposes.
Types of firewalls Several types of firewalls exist and range in size from personal one-user versions to complete interprise systems designed to protect tens of thousands of computers. Most common however are as follows Personal windows based software. Each type of firewall has its' own pros and cons. Personal firewalls are useful for single users, but become hard to manage in a multi-user network. Larger systems typically cost more and require more skill to manage.