Legitimate email messages that are mistaken as spam.
farming
See pharming .
file infector virus
A type of computer virus that attaches itself to a program file. It executes when the file is run.
filename extension
A three-character suffix that is part of a computer file name (for example, .jpg and .doc ). Common to files on a PC.
firewall
A device or program that blocks outsiders from accessing a computer connected to the Internet. Some firewalls also monitor data traffic outbound from a computer or network.
firmware
Programming stored on a chip inside a device (such as a network router) that controls it.
