CS 111 – Oct. 11 Internet topics –Network applications and technology for business –Security Commitment: –Quiz Wednesday. –Homework #1 due Oct. 18: Discuss your favorite infamous example of a computer crime. Why is it significant, and could it happen again?

Network applications Both client and server software necessary Many are same as personal applications – –Voice mail But others are services that people expect from some establishment –Videoconferencing –Bulletin board (i.e. forum) –Electronic funds transfer, and credit card transactions !

Network architecture Within a company, may be centralized or distributed Need backups of software as well as data –E.g. NASDAQ during 9/11 Use a WAN to connect major operators (e.g. stores in a chain) Network operating system –Distinct from each machine’s OS –Handle system logins and traffic in WAN

Download speed Overhead time – prepare and assemble message Flight time – first bit to arrive at destination Bandwidth – max rate to propagate data (Cruising speed). Divide size by rate. Total time = overhead + flight time + (msg size / bandwidth) Unless message is tiny, bandwidth is crucial issue. Rules of thumb for home users: –Dial up: 10 MB per hour –DSL: 10 MB per minute

Internet backbone Telecoms maintain traditional phone lines as well as fiber optic cables. “T-carriers” range from T-1 (1.5 Mbps) to T-4 (274 Mbps) –Your business can subscribe to dedicated continuous Internet connection. Ex. Furman subscribes to 200+ Mbps level of service. Fiber optic: OC-1 (51 Mbps) to OC-192 (10 Gbps) Fiber optic generally limited to urban areas

Security Areas include security of the… –Physical site (traditional notion of security) –IT resources – such as printer, files –Network – ability to communicate –Service – whatever the firm deals with Results of breaches: –Destruction of resources, information, service –Corruption of data –Denial of service –Theft –Fraud, e.g. cheating the company or defrauding the public

Security issues Viruses, Trojan horses, etc. Firewall for firm’s network –Distinguish between intranet and Internet –Firewall is any system that specifies what traffic to allow in either direction Maintain backups of everything –Note: Accidents happen. Power goes out, people delete files… Audit Internet traffic to/from site looking for anomaly Encryption: Make transmissions secure –https and.shtml