COSC513 Final Project Firewall in Internet Security Student Name: Jinqi Zhang Student ID: Instructor Name: Dr.Anvari

Outline  Internet Security  Concept of Firewall  Types of Firewall  How Firewall works  Building Firewall  Limitations of Firewall

Internet Security  Internet and security  Internet conveniences  Easy communication  Convenient tool for obtaining information  Doing business  Trade-off between convenience and security  No access, no attack  More access, more vulnerable

Internet Security  Purpose of Security  Keeping anyone from doing things you do not want them to do to, with, on, or from your computers or an peripheral devices  Protecting corporate network from illegal Internet access  Strategies for a secure Network  Strategy: building firewall

Concept of Firewall  Firewall  Hardware and software combinations to protect inside network that are built using routers, servers, and a variety of software  Role  A firewall shields the Internal corporate network from the Internet  The Internal network works normally Inside Outside gateways filter

Types of Firewall  Common types of firewall  packet filtering  proxy server Internet Corporate Computer Proxy Server Outside Internet...….. Router (a) (b) Inside Computer

Types of Firewall  Packet filtering  Central component  A screening router -- which examines the header of every packet of data traveling between the Internet and corporate network  Information in the head of a packet  IP addresses of the sender and receiver  The protocol being used to send the packet  Other similar information

How Firewall Works  Packet filtering  Working process  Router figures out what kind of services, such as FTP or rlogin  Router figures out which packets to allow to pass, which packets to block  Warning  Some commands such as rlogin, telnet allows users to bypass passwards, potential security compromise

Types of Firewall  Proxy server  A server software that runs on a host in a firewall, such as bastion host  Often a single proxy server (instead of the many individual computers on the network) interacts with Internet  Limited access to Internet, more security

How Firewall Works  Proxy Server (an example)  step 1: A request from a corporate network  step 2: That request being Sent to proxy server  step 3: A proxy server sends the request to the targeted Internet server  step 4: The internet server fulfilled the request and sends the answer back to proxy server  step 5: The proxy server sends the answer back to the corporate network Internet Corporate Computer Proxy Server

Building Firewall  Positioning Firewalls Internet Net 5 Net 4 Net 6 Net 3 Net 2 Net 1

Limitations of Firewall  No protection against problems with higher level protocols  The degree of protection against threads depends on how carefully the gateway code is written  Any information that passes inside can trigger problems  At best, a firewall provides only a convenient single place to apply a corrective filter.

 Any question  Good luck on your presentation ! Thanks for being with me!