By: Colby Shifflett Dr. Grossman Computer Science /01/2009

 Before the use of firewalls, networks were extremely vulnerable to intrusions and data leaking. ◦ Extremely weak security ◦ No virus security  The first firewall was introduced in 1985 by the IOS software division - Cisco  The first published papers on firewalls was not until 3 years after its first deployment by Digital Equipment Company

 A firewall is a system or set of systems that are used to control access ◦ Designed to block all unauthorized communication and accept all authorized.  According to Cheswick and Bellovin, AT&T Bell Labs firewall engineers, a firewall should be used as a network chokepoint. (Late 1980’s)

 First Generation Firewalls are also known as packet filtering firewalls  Packet filtering routers were key in making the first firewalls  Very simple filtering device ◦ Have a set of rules for the firewall  Ip, port, or protocol based ◦ Based on set of rules, accept or reject communication request  Uses packet header

 Network packet filtering offered more security than ever before for networks  Was very straight forward to understand, implement, and manage ◦ Greatly helped popularity in commerce business  Evolved extremely quickly after first working model demonstrated its capabilities

 Second Generation Firewalls are also known as Circuit Level Firewalls  Validates connections prior to allowing data exchange  After validation, a session is open and only data from source is permitted access ◦ Every exchange of information is validated and monitored  Source/Destination Ip or port, time of day, user, password, or protocol are validation methods  No data is accepted unless a session is open

 Third Generation Firewalls are also known as Application Layer Firewalls or Proxy Firewalls  Operate at the 7 th or Application layer of the OSI model ◦ Monitors the protocol that is being used  Have the ability to run as a piece of software or a standalone device ◦ Software firewalls are still very commonly used today  McAfee  Norton  DEC’s first release was named SEAL and grew quickly in popularity

 Fourth Generation Firewalls are also known as stateful firewalls  Most important upgrade from First Generation Firewalls is the ability to keep track of the TCP connection state ◦ Greatly prevents hackers access ◦ Firewalls are able to determine if packets are a part of a new connection or existing connection  Relies on a three way handshake with TCP

Thanks for listening!