4. Merits and Pitfalls

Global access
Obtain the most updated information,says the The poll of US 96 election
Information can spread out many sites within a very short period of time.
Your messages can be read by many users world-wide via different electronic channels.
The cost of information updating can be minimum.

Validity of information on internet
As everyone can put their information on the net, how do you know that their information is true or valid? Hence, getting good reputation on the Internet is important for your audiences to trust your information.
Authentication of service providers and customers
When a customer fill out an order or request form on the net, how does he sure that this order form is from the real service providers? Other the other hand, when a service provider receives an order or request form on the net, how do they know that the information stated on the form is real?
Privacy
When we send our personal information(such as credit card no., tel no or home address) on the net for ordering or membership registration, how do we sure that this information will not be intercepted by others or not be used for other purpose?
Copyright
As information can pass freely on the internet, how can we prohibit the others from copying our materials and violating our copyright?
Censorship
How can we protect our children from illegal material on the internet such as cypberporn, Terrorists handbook or bomb making menu and at the same time preserve our freedom of speech and information access?

What can hackers do when they break into your system

can destroy your data including your log files
can steal your confidential information such as personal e-mail or password file
can change the data of your servers such as the contents of your web pages, database records or entries in log files
can use your system as a stepping stone to break into other sites
can use your system to distribute illegal materials such as pornographic pictures
can use your accounts to send fake mail or post fake news
can install some Trojan Horse programs for back door purpose

How to prevent break-in

Set up good security policies such as rules of user password, remote access or system audit.
Understand the sub-culture of hackers and their usual techniques to break in systems.
Cover all well-known security holes. Make sure that your system does not have any security holes which have been mentioned in some common hackers' literature.
Build firewall to control the internet access to your system.
Refer the Orange Book (The Trusted Computer Standards Evaluation Criteria by the United States Department of Defense) to determine your system security levels .

What can you do when your network is attacked by hackers

Stop any future damage, says temporary disconnecting your network from outside, cleaning any suspicious files or programs in your systems. In the worst case, you may need re-install your network in order to remove Trojan Horse programs.
Trace the originality of the hackers from all log files and network activities.
Seek technical help from CERT
Report the attack to the police if needed. There is a telecommunication ordinance in HK to charge computer outlaws.
Clean up your network and resume your service as soon as possible.
Review your security measures.

References:

Hacker Attack by Stephen James