Chapter 8

Safeguarding the Internet

Firewalls

Firewalls: hardware & software that are built using routers, servers and other software

A point between a corporate network and the Internet System administrator Packet filtering: a screening router examines the header

of every packet of data traveling Router could block any traffic Proxy Server: server software that runs on a host in a

firewall A request from the corporate network’s computer is sent

to the proxy server, which contacts the server on the Internet, and then sends the information from the net server to the computer

Viruses Malicious programs Cause different kinds of damages: deleting files,

removing programs Computer (PC or Macintosh) can infected by

viruses from: networks, e-mails, removable storage Viruses attach themselves to four parts:

1) Program files2) File-directory system3) Boot and system areas4) Data files

Trojan horses, Worms Anti-Virus Software (Eradication Program): System

scanning

Cookies & Tracking Work

Cookies: bits of data put on a hard disk when someone visits a web site

Easier for people to use Web sites that require a user name and password

Track how people use a Web site Users have the option of not allowing cookies to be

placed on their hard disks (browsers option) Other methods:

1. Examine Web server logs in details

2. Using “sniffers” to examine every packet

3. helpful for Webmasters to create better sites

Cookies & Tracking Work

OPS: Open Profiling Standard To allay people’s privacy concern, some

organizations such as Microsoft & Netscape agreed on an “OPS”

Give people much more control OPS is integrated into browsers

Cryptography and Privacy

Internet will never be a secure place to do business or send private information

Information needs to be encrypted & decrypted by “cryptosystems”

Keys: secret values that computers use to encrypt and decrypt messages

The idea is: if someone encrypts a message with a key, only someone else with matching key can decrypt the message

Cryptography and Privacy Encryption system’s kinds:1) Secret-key cryptography “symmetric

cryptography”: one secret key2) Public-key cryptography “asymmetric

cryptography”: two keys, public & private Data Encryption Standard (DES) is the most

common secret-key cryptography system The best known public-key system is (RSA) A public-key system is useful for business

on the Internet