print friendly version

Questions and answers

What is a Firewall?

A Firewall is a machine installed on a network, or a suite of software installed on a computer, to limit possible damage to computers and information inside the firewall from computers/people on the outside of the firewall. It can also limit inappropriate access to external systems outside the firewall from computers/people inside the firewall.

A firewall can be configured to deny specific network services (e.g. WWW, telnet, ftp, Internet Relay Chat), from specific network sources (machines, sites, etc).

Firewalls are often deployed to protect corporate networks from intruders, with everything on the wrong side (the outside) of the firewall taken to be untrustworthy and dangerous, and everything on the inside being safe.

Corporate firewalls tend to be expensive, complex and tightly configured, with very few services being permitted, and even then not transparently (i.e. with lots of extra passwords and stages involved in getting to information on the Internet).

In a University environment, this kind of configuration is not compatible with open environments for learning and research, even if the University could afford the cost and effort of maintaining such a configuration. As a consequence, IT Services at Sussex has configured our firewall to have as low an impact on users of the network as possible without compromising its purpose.

Help us to improve this answer

Please suggest an improvement
(login needed, link opens in new window)

Your views are welcome and will help other readers of this page.


This is question number 639, which appears in the following categories:

Created by Jason Bailey on 27 July 2001 and last updated by Richard Byrom-Colburn on 31 October 2016