What is the use of a firewall?

Here are some benefits of firewall. Because of these benefits we use Firewall. Provide VPN capabilities A Virtual Private Network (VPN) is quite simply a secure connection between remote offices or clients using the Internet. A VPN uses sophisticated encryption and encapsulation technology to allow data to be securely transmitted and received. Using broadband to create secure, low cost communications is one method in which companies can save significant sums over traditional ways of connecting remote offices and workers. A VPN can be configured between remote offices, workers, or a combination of both. Allow content filtering Content Filtering can help organizations increase productivity and reduce legal and privacy risks by automatically enforcing acceptable Internet use policies at the Internet gateway. Businesses requiring Internet use policies can implement them on a firewall with content filtering capability. Content filtering is usually based on, but not limited to: site categories, time of day and trusted and forbidden domains. Most firewall content filtering packages are subscription based, and include automatic updating of the filters, making maintenance simpler and less time consuming. Anti-Virus By default a firewall will not prevent users contracting viruses from the Internet. However some firewalls do have the ability to offer virus protection and it is usually on a subscription basis. The exact functionality, if any, of virus protection offered by a firewall may vary dramatically and we advise any customer considering using a firewall to protect against viruses to carefully check the exact details of the equipment before purchasing. DMZ Port A DMZ port normally allows one or more computers to sit between a trusted internal network and an insecure external network, such as the public Internet. Internet facing servers are normally attached to a DMZ port, which can offer protection from attacks whilst allowing the relevant services to flow freely to and from the Internet. Be aware As good as firewalls are at protecting networks from Internet attacks there are a number of instances where a firewall will not offer protection. Malicious users within the network can cause real damage as can poor network administration including lack of or simple passwords and poor access rights and policies. Compromised remote authorised VPN users are also a liability as their network privileges can be used by a hacker to gain access to the corporate network. Not all firewalls offer the functionality listed here. Please check with the manufacturer of any particular make and model you wish to deploy. Our sales team will be able to answer any questions you have regarding our entire range of Internet and associated services.

The primary method for keeping a computer secure from intruders. A firewall allows or blocks traffic into and out of a private network or the user's computer. Firewalls are widely used to give users secure access to the Internet as well as to separate a company's public Web server from its internal network. Firewalls are also used to keep internal network segments secure; for example, the accounting network might be vulnerable to snooping from within the enterprise. In the home, a personal firewall typically comes with or is installed in the user's computer (see Windows Firewall). Personal firewalls may also detect outbound traffic to guard against spyware, which could be sending your surfing habits to a Web site. They alert you when software makes an outbound request for the first time (see spyware). In the organization, a firewall can be a stand-alone machine (see firewall appliance) or software in a router or server. It can be as simple as a single router that filters out unwanted packets, or it may comprise a combination of routers and servers each performing some type of firewall processing. Source: http://www.answers.com/firewall?initiator=IE7:SearchBox

All Firewalls do not block virus. If the firewall has a anti-virus module integrated than only it will block the virus.