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