LAN is Local Area Network for short. It mainly refers to a small working group network composed of server/servers and multiple computers. A LAN can be regarded as a branch of Internet. Each computer in a LAN is connected through server/servers; therefore information transmission rate is relatively high in LAN. However, it also provides an effective channel to the spread of viruses. Usually a virus in the LAN can spread through several channels below:

 

 

1 As part of the greatest LAN use is resource sharing. The openness of resources sharing leads to the direct infection of viruses.

 

 

2 Some servers in LAN are low-end servers or general PCs. These servers are not very powerful in performance and security features. So when a computer in the LAN transmits data through the server and if the server has been infected with viruses, all the data transmission through the server will be infected, thereby causing the infection of the whole network.

 

 

3 The greatest feature of LAN is data transmission is easy and fast. However, if one computer is infected with viruses, any other computers have data transmission with the virus infected computer are extremely easy to be infected.

 

 

4 If a virus infected computer in the LAN transmits data through a server, this server will be easily infected and then any computers transmitting information through this sever will be easily infected.

 

 

5 LAN users do not have a solid knowledge of computer viruses protection, thus giving the chance of recurrent infection.

 

 

These unique features of the LAN cause rapid transmission of viruses and mutual infection and the viruses are hard to clean thoroughly.