An unknown network is neither trusted nor untrusted and, by default, is treated the same as an untrusted network

You can use firewall software to enable the following security measures on all untrusted and unknown networks:

Packet filtering

Virtual private networks

IPX/IP gateways

Circuit-level gateways

Proxy services

Protection Against Virus Attacks

• Viruses are often embedded in other programs or e-mail attachments

• After a virus is activated by running the program or opening the e-mail attachment, it can copy itself to other programs or disk storage areas

• Each virus has a different signature, which is a bit pattern made by the virus when it’s embedded in a program or an e-mail attachment

• Firewalls offer security measures to help protect a network from information theft and attacks, but they are not designed to detect and prevent viruses from entering the network

• Viruses are classified based on how they infect computer systems:

• Boot sector viruses

• File viruses, also called Trojan horses

• Macro viruses

• Stealth viruses

• Polymorphic viruses

• Worms

Virus Prevention Techniques

• Virus prevention on a network involves installing a virus protection system, making regular backups, and training users on how to reduce the risk of virus attacks

• Virus protection systems scan programs on the server and user workstations and monitor program files as they are loaded to detect known virus signatures

• Refer to the list on pages 462 and 463 of the textbook for common virus infection symptoms

Virus Removal Planning

• Despite security measures and anti-virus software, with all the new viruses popping up almost daily, there’s always the possibility that one could slip by your anti-virus software and infect your network’s computers

• After a virus was detected recently on the UAS, you used the procedure shown on pages 463 and 464 of the textbook to isolate and remove the virus from all networked computers

Defense Against
Denial-of-Service Attacks

• Although denial-of-service attacks don’t usually directly damage or steal a company’s data, they can cost a company a lot of money by bogging down the organization’s Web services, causing lost customer sales and reducing user productivity

• Denial-of-service attacks are usually caused by flooding the server with packets or sending oversized packets to a service, causing it to crash

Common Denial-of-Service Attacks

Summary

• An essential part of Novell’s strategy for the future is to provide Internet services that enable clients and servers using diverse operating systems to be managed and accessed as one network

• NetWare Web Services includes Enterprise Web Server and FTP Server, which can be installed and customized to supply information and Web pages to the Internet and local intranet

• Using public key cryptography to encrypt data transmission and provide authentication with digital signatures is a vital component of securing information transmission on the Internet

• Certificate Authorities issue public key certificates for verifying that the public key belongs to the entity distributing it

• Internet security involves protecting Web and Net Services from threats such as data theft, hacking, and computer viruses