1. Operating Systems Proj.

2. Background A firewall is an information technology (IT) security device which is configured to permit, deny or proxy data connections set and configured by the organization's security policy. Firewalls can either be hardware and/or software based.

3. Why Firewall? A personal computer connected to the Internet without a firewall can be hijacked in just a few minutes. The only way to make it 100% secure is to turn it off or disconnect it from the Internet. The real issue is how to make your computer 99.9% secure when it is connected. Basically, a firewall is a program that protects one computer from other computers. It examines information that tries to enter a computer from the outside (i.e. the internet), and determines if the information is safe or harmful.

4. Context Firewall Most of the firewalls are designed to block a port or set of IP's without checking their context. However, our product is designed to consider this context and allows the user to define rules between protocols and ports.

5. Rules Examples For port 25 allow only SMTP protocol. For port 80 allow HTTP and HTTPS protocols. For port 1024 allow all For port 1025 allow none.

6. Client Stories The system is a Firewall, buffering between the user and the other stations. The system was designed to sit above the IP layer. The system is capable of permitting, denying or limiting net services. The system can recognize the protocol according to the pattern of regular expression and react accordingly by blocking or ignoring the session.

7. Client Stories cont. The system has an interface allowing the user to define rules. All the rules passed to the system through the iptables. http://www.netfilter.org/projects/iptables/index.html http://www.netfilter.org/projects/iptables/index.html The system allows logging. There is log file which records all the events which happened in the system.

8.  The system allows checking the correspondence between arriving protocol's message and the port from where it arrived.  Will be explained in the design.  The system is efficient.  Uses minimum possible resources.  Most of its parts running in the kernel mode. Client Stories cont.

9. General Design

12. Measurements - CPU Before After

13. Measurements – man hours