Synonyms: Personal Firewall
This term is taken from the world of fire fighting, where a firewall is a barrier created to block the spread of a fire.
In computing, a firewall forms a barrier between a computer system (either a corporate system or a single user) and the outside world: the aim is to prevent outsiders from gaining unauthorized access to the protected network. The firewall monitors incoming and outgoing network traffic and decides whether to forward it or block it depending on the security policy that has been set.
Typically, a firewall is installed on a router at the Internet gateway, although it may also be used to guard the boundaries between networks and user groups.
Today, most enterprises use ‘stateful’ firewalls: they monitor the state of network connections over a period of time (rather than simply examining packet headers). The system administrator creates lists of legitimate data packets for each connection and the firewall passes only packets which match known connections and reject all others.
Personal firewalls are software-based. They protect single users from hacker attacks and potentially damaging data packets sent via the Internet and also limit the scope of applications on the protected computer. Such protection, as a supplement to anti-virus protection, has become a ‘must’ for those with always-on broadband connections.
Synonyms: False positive
A false positive is another way of saying ‘mistake’. As applied to the field of anti-virus programs, a false positive occurs when the program mistakenly flags an innocent file as being infected. This may seem harmless enough, but false positives can be a real nuisance.
In short, false positives can be costly nuisances.
The term is not confined just to the anti-virus world. It also applies, for example, to anti-spam protection, where it refers to the misidentification of a legitimate e-mail message as spam. This too could be very costly, since the undelivered e-mail may be a business critical message.
A false negative is simply another name for missing something. Applied to anti-virus programs, it refers to a failure to detect malware that is present on a system.
The term FAT is used to describe the file system used by Microsoft® MS-DOS, Windows® 9x and Windows® ME operating systems. Specifically, the file allocation table is the index used by the operating system to keep track of the clusters (a group of disk sectors) belonging to each file stored on a disk. Clusters are the basic unit of logical storage used by the operating system: and the FAT is required because the clusters belonging to a file may not be stored contiguously. When a file is written to the disk, the operating system creates a FAT entry for the file: this notes the location of the file’s start cluster and its overall size. When access to the file is later required, the operating system can then piece together each cluster belonging to the file and load the file into memory for processing.
Alternative file systems are NTFS, used by Windows® NT, Windows® 2000 and Windows® XP, and HPPS [High Performance File System] used by OS/2.
FTP is a protocol for exchanging files between computers on the Internet and is often used to download files. FTP can be accessed from the command prompt, or through a web browser.
Viruses are often classified according to the objects they infect. File viruses, as the name suggests, are designed to add their code to files (generally program files).
Formatting is the process by which a new disk is prepared for use by the operating system.