Network Security Glossary
A list of frequently used terms
This glossary contains a list of terms, abbreviations, and acronyms frequently used when discussing networks, security, firewalls, and WatchGuard products.
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N
- name resolution
- The successful look-up of an IP address to discover the name of the networked computer it indicates.
See DNS.
- NAT (Network Address Translation)
- A technology where you advertise one IP address for the world to send stuff to (e-mails, HTTP, database traffic, whatever). Then the Firebox translates that request from the outside world and sends it to the appropriate IP address inside your network. In this way, the Firebox can hide from outsiders the IP addresses of machines on your internal network. Various techniques for applying NAT include dynamic NAT, and static NAT. Some people use the term NAT interchangeably with masquerading.
- National Institute for Standards and Technology
- See NIST.
- NetBIOS (Network Basic Input/Output System)
- An older proprietary Microsoft networking protocol that enables a computer to connect to and communicate with a Local Area Network (LAN).
- NetBEUI (NetBIOS Extended User Interface)
- A non-routable networking protocol used by smaller, non-subnetted networks for internal communications. Because NetBEUI is not publicly routable, network transmissions sent via NetBEUI cannot be transmitted over the Internet.
- network address
- The network portion of an Internet Protocol (IP) address. For a Class A network, the network address is the first byte of the IP address (e.g., in 74.10.10.10, the network address is 74). For a class B network, the network address is the first two bytes of the IP address (e.g., in 128.10.10.10, the network address is 128.10). For a class C network, the network address is the first three bytes of the IP address (e.g., in 192.168.10.10, the network address is 192.168.10). In each case, the remaining bits can be used to identify specific computers, often called hosts. In the Internet, assigned network addresses are globally unique; that is, a computer cannot have the same IP address as any other computer with which it can communicate.
See also CIDR block addressing, Internet address class, and subnet mask. For a very full discussion of these concepts, see the LiveSecurity articles, "Foundations: Understanding IP Addresses and Binary," "Foundations: Understanding Subnetting (Part 1)," and "Foundations: Understanding Subnetting (Part 2)."
- network address translation
- See NAT.
- netmask
- See subnet mask.
- Network Configuration wizard
- Automated software presenting a series of windows. The various windows and fields prompt you for essential information that helps create a basic Firebox configuration.
- network adaptor, network interface card (NIC)
- A device that sends and receives data between the computer and the network cabling. Every computer attached to a network must have a NIC.
- network range
- See subnet mask.
- network segment
- A subdivision of a computer network, bounded by a device such as a router, switch, or even a Firebox. Dividing an Ethernet into multiple segments is a common way of increasing available bandwidth on the individual segments.
- NFS (Network File System)
- A popular TCP/IP service for providing shared file systems over a network. NFS allows all network users to access shared files stored on computers of different types. A user can manipulate shared files as if the files were stored locally on the user's own hard disk. NFS is typically found on Unix computers.
- NIST (National Institute for Standards and Technology)
- A division of the U.S. Department of Commerce that publishes open interoperability standards called Federal Information Processing Standards (FIPSs). Part of NIST's charter is to distribute complete and accurate information about computer security issues to government and the general public.
- node
- A computer or CPU on a network.
- non-seed router
- A router that waits to receive information (the routing maintenance table) from other routers on the network before it begins routing packets.
- NTP (Network Time Protocol)
- An Internet service used to synchronize clocks among Internet hosts. Properly configured, NTP can usually keep the clocks of participating hosts within a few milliseconds of each other.
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