Security

Firewalls

Firewall is a generic term to describe a hardware and software package that defines, controls and limits access to internal or secure networks from external or unsecured networks such as the Internet. (Phew!)

Some examples of popular Firewall implementations are :

Packet Filter

A router that filters packets flowing through it based on IP address. It can prevent for example a range of IP addresses from reaching your intranet. It can not differentiate between applications such as TELNET or HTTP.

Proxy Server

A 'stand-in' machine that hides internal IP addresses from the outside world. It uses its own IP address in place of the internal systems'.

Socks Server

Similar to a Proxy Server but with less overhead. Requires 'SOCKSified' clients such as OS/2's WebBrowser.

Let's use the OSI 7 layer model to distinguish between Packet Filter and Firewall Gateway:

Agenda

SEC060