Viruses are programs that attempt to spread from computer to computer and either cause damage by erasing or corrupting data or annoy users by printing messages or altering what is displayed on the screen.
By taking the following precautions, you may prevent intrusions by viruses.
Educate your network users. Few realize that they unwittingly can bring viruses into the network by loading a program from a source such as an online bulletin board.
Have at least one commercial virus-detection program and use it to regularly to check your file servers for viruses. If possible, you also should make virus-detection software available to your users.
Set file permissions to make all applications available on network Read and Execute only, thereby preventing them from being replaced by viruses.
Before putting a new application or file on the network, put it on a computer not attached to the network, and check it with your virus-detection software. You also may want to log on to this computer using an account with only guest access to the computer so that the program being tested will have only guest permissions and be unable to modify any files.
Regularly back up the files on your file servers so that damage is minimized if a virus attack does occur.