.NET Passport
.NET Passport, now called Windows Live ID, is a system developed by Microsoft Corporation for managing online identity. It is a "unified-login" service that allows users to log in to many websites using one account. It was originally positioned as a single sign-on service for all web commerce.

NAPT: Network Address Port Translation
Network Address Port Translation (NAPT) is a method by which many network addresses and their TCP/UDP ports are translated into a single network address and its TCP/UDP ports. Together with the basic NAT (Network Address Translation), it provides a mechanism to connect a realm with private addresses to an external realm with globally unique registered addresses.

NAT: Network Address Translation
Network Address Translation (NAT) is a method by which IP addresses are mapped from one group to another, transparent to end users. The need for IP Address translation arises when a network's internal IP addresses cannot be used outside the network either for privacy reasons or because they are invalid for use outside the network.

National Communications System
National Communications System is an office within the United States Department of Homeland Security charged with enabling national security and emergency preparedness communications using the national telecommunications system.

National Identity Card
A national identity card is a portable document such as a plastic card with digitally-embedded information for people to carry as a means of confirming their identity.

National Strategy to Secure Cyberspace
National Strategy to Secure Cyberspace refers to the information security (infosec) component of the U.S. National Strategy for Homeland Security.

Natural Disaster
Natural Disaster refers to any "act of God" (e.g., fire, flood, earthquake, lightning, or wind) that disables a system component.

Nbtscan
Nbtscan is a tool for automating NetBIOS scans of remote networks. Nbtscan scans for open NETBIOS nameservers on a local or remote TCP/IP network, and this is a first step in finding of open shares. It is based on the functionality of the standard Windows tool nbtstat, but it operates on a range of addresses instead of just one.

Nbtstat
Nbtstat is a command-line tool for displaying NetBIOS over TCP/IP (NetBT) protocol statistics, NetBIOS name tables for both the local computer and remote computers, and the NetBIOS name cache. Nbtstat allows a refresh of the NetBIOS name cache and the names registered with Windows Internet Name Service (WINS). Used without parameters, nbtstat displays help.

NCSC: National Computer Security Center
The National Computer Security Center (NCSC) is a U.S. government organization within the National Security Agency (NSA) that evaluates computing equipment for high security applications to ensure that facilities processing classified or other sensitive material are using trusted computer systems and components.

Nemesis
Nemesis is a packet generation and crafting tool, which can be used by attackers to forge packets for the purpose of compromise, crash or fool systems or network equipment. They are nemesis-arp, nemesis-dns, nemesis-icmp, nemesis-igmp, nemesis-ospf, nemesis-rip, nemesis-tcp, and nemesis-udp. Each is designed to construct and send a particular type of packet. The inclusion of support for protocols like OSPF or IGMP really sets nemesis apart from similar tools.

Netbus
Netbus is a software program for remotely controlling a Microsoft Windows computer system over a network. It was created in 1998 and has been very controversial for its potential of being used as a backdoor. There are two components in the Netbus client-server architecture. The server must be installed and run on the computer that should be remotely controlled. Common names were "Patch.exe" and "SysEdit.exe". When started for the first time, the server would install itself on the host computer, including modifying the Windows registry so that it starts automatically on each system startup. The server is a faceless process listening for connections on port 12345 and port 12346 is also used. The client was a separate program presenting a graphical user interface that allowed the user to perform a number of activities on the remote computer such as Keystroke logging, Keystroke injection, Screen captures, Program launching, File browsing, Shutting down the system, Opening / closing CD-tray, Tunneling NetBus connections through a number of systems, etc.

Netcat
Netcat is a utility for port scanning and transferring information over network connections on either TCP or UDP. It is designed in a thin and simple way, which makes it easy to incorporate in larger applications. The original version of netcat is a UNIX program. Netcat is fully POSIX compatible and there exist several implementations, including a rewrite from scratch known as GNU netcat, and a MS-Windows version of netcat. Also, an encrypted version of netcat named Cryptcat is available for use when security is of concern. On some systems, modified versions or similar utilities go by the command name(s) nc, ncat, pnetcat, socat, sock, socket, spd. Netcat is sometimes detected and flagged up as a security risk by virus scanners and spyware removal software, which may simplistically categorise it as a remote administration tool, or treat it as a hacking tool which may have been planted by malicious software.

Netmask
Netmask is a 32-bit number indicating the range of IP addresses residing on a single IP network/subnet/supernet.

Netstat
Netstat is a command-line tool that displays a list of the active network connections the computer currently has, both incoming and outgoing. Netstat is available on Unix, Unix-like, and Windows NT-based operating systems.

NetStumbler
NetStumbler is a freely available Windows utility for wireless lan discovery. It is useful for site surveys, detecting rogue access points, and finding and mapping WLAN installations.

Network Encryption
Network encryption, also called network layer or network level encryption, is a network security process that applies crypto services at the network transfer layer - above the data link level, but below the application level.

Network Firewall
A network firewall is a network based firewall devices that protect a computer network from unauthorized access. Network firewalls may be hardware devices, software programs, or a combination of the two. A network firewall typically guards an internal computer network against malicious access from the outside; however, network firewalls may also be configured to limit access to the outside from internal users.
Perhaps the most common form of network firewall is a proxy server. Proxy servers act as an intermediary between intranet and Internet computers by receiving and selectively blocking data packets at the network boundary. Network firewalls may also provide an extra functions of safety by hiding internal LAN addresses from the outside Internet. In a proxy server firewall environment, network requests from multiple clients appear to the outsider as all coming from the same proxy server address.

Network Forensics
Network forensics is the capture, recording, and analysis of network events in order to discover the source of security attacks or other problem incidents.

Network Hardening
Network hardening is a process to address network security vulnerabilities by implementing software version/patches, introducing new security systems and adopting better configurations and operation policies.

Network Layer Firewall
Network layer firewall is a type of firewall that works as a packet filter by deciding what packets will pass the firewall according to rules defined by the administrator. Filtering rules can act on the basis of source and destination address and on ports, in addition to whatever higher-level network protocols the packet contains. Network layer firewalls tend to operate very fast, and transparently to users. Network layer firewalls generally fall into two sub-categories, stateful and non-stateful. Stateful firewalls hold some information on the state of connections as part of their rules. Stateless firewalls have packet-filtering capabilities but cannot make more complex decisions on what stage communications between hosts have reached. Stateless firewalls therefore offer less security.

Network Mapping
Network mapping is the study of the physical connectivity of the Internet. It is not to be confused with the remote discovery of which operating system a computer is running, an activity more akin to hacking.

Network Perimeter
A network perimeter is the boundary between the private and locally managed-and-owned side of a network and the public and usually provider-managed side of a network.

Network Scanning
Network scanning is a procedure for identifying active hosts on a network, either for the purpose of attacking them or for network security assessment. Scanning procedures, such as ping sweeps and port scans, return information about which IP addresses map to live hosts that are active on the Internet and what services they offer. Another scanning method, inverse mapping, returns information about what IP addresses do not map to live hosts; this enables an attacker to make assumptions about viable addresses.

Network Sniffing
Network sniffing refers to a computer connected to a network through "promiscuous mode", listening to every bit of traffic that goes by on the network and captures all the data. Normally a computer's network connection ignores traffic that is not addressed to it, but with sniffing software the computer will pick up everything. This is an easy way to pick up clear text passwords. E-mail programs frequently use clear text passwords.

Network Taps
Network taps are hardware devices that hook directly onto the network cable and send a copy of the traffic that passes through it to one or more other networked devices such as network sniffing tools.

Network Security Hotfix Checker
Network Security Hotfix Checker, also called HFNetChk, is a Microsoft tool for keeping security patches up to date on a system.

Network-Based IDS
A network-based IDS system monitors the traffic on its network segment as a data source. This is generally accomplished by placing the network interface card in promiscuous mode to capture all network traffic that crosses its network segment. Network traffic on other segments, and traffic on other means of communication can't be monitored. Packets are considered to be of interest if they match a signature. Network-based intrusion detection passively monitors network activity for indications of attacks.

Network-based security
Network-based security refers to the practice of hardening the elements of a network to protect other devices.

Newtear
Newtear is a denial of service (DoS) exploit against machines running on the Microsoft Windows platforms. The Newtear attack is a modified version of the Teardrop attack. Newtear exploits a problem with the way the Microsoft TCP/IP stack handles certain exceptions caused by misformed UDP header information. This situation does not occur in properly formed TCP/IP packets, and must be generated by a program with malicious intent.

NFIC: National Fraud Information Center
National Fraud Information Center (NFIC), a project of National Consumers League, is an organization helping consumers and law enforcement agencies fight fraud. NFIC provides information, referral services, and assistance in filing complaints. It gives professionals involved in consumer fraud prevention and law enforcement access to advanced communications and data systems. The result is improved regulation, prevention, apprehension, and enforcement.

NFS Attack
NFS Attack refers to attacks on the Network File System (NFS) system, which allows a computer on a network to use the files and peripherals of another networked computer as if they were local. An attacker may be able to NFS-mount remote file systems without authorization. Client machines, which maybe controlled by an attacker, are allowed to read and change files stored on the server without logging into the server or entering a password.

Ngrep
Ngrep is a tool for “grepping” (searching for) specific information in network packets. Ngrep is a pcap-aware tool that allows users to specify extended regular or hexadecimal expressions to match against data payloads of packets. It currently recognizes IPv4/6, TCP, UDP, ICMPv4/6, IGMP and Raw across Ethernet, PPP, SLIP, FDDI, Token Ring and null interfaces, and understands BPF filter logic in the same fashion as more common packet sniffing tools, such as tcpdump and snoop.

NIACAP: National Information Assuranc Certification and Accreditation Process
National Information Assuranc Certification and Accreditation Process (NIACAP) is a U.S. national standards process for information assurance (IA) accreditation.

NIAP: National Information Assurance Partnership
National Information Assurance Partnership (NIAP) is a cooperative agency for promoting information security (infosec) in U.S. government agencies and private industry.

NIDS: Network-based intrusion detection system
Network-based intrusion detection system(NIDS) refers to an intrusion detection system (IDS) that monitors activity on a network, instead of a particular host.

NIETP: National INFOSEC Education & Training Program
National INFOSEC Education & Training Program is an information security training program from the National Security Agency (NSA).

NFC: Near Field Communication
Near Field Communication (NFC) is a short-range wireless connectivity standard jointly developed by Philips and Sony that uses magnetic field induction to enable communication between devices when they're touched together, or brought within a few centimeters of each other. The standard specifies a way for the devices to establish a peer-to-peer (P2P) network to exchange data.

NFS and NIS Attacks
Network File System (NFS) allows a computer on a network to use the files and peripherals of another networked computer as if they were local. NIS maintains a distributed database of password tables, group files, host tables, and other information that systems on a network can share. An attacker may be able to NFS-mount your filesystems. Client machines are allowed to read and change files stored on the server without logging into the server or entering a password. An attacker who can guess the name of your NIS domain and can send a NIS request to the NIS server can get a copy of your password information.

Nimda
Nimda is a computer virus that caused traffic slowdowns as it rippled across the Internet, spreading through a few different methods: infecting computers containing Microsoft's Web server, Internet Information Server (IIS), and computer users who opened an e-mail attachment.

NIPC: National Infrastructure Protection Center
National Infrastructure Protection Center(NIPC) is a cooperative agency under the US Department of Justice. Federal Bureau of Investigation to help protect critical information system infrastructures. NIPC serves as a national critical infrastructure threat assessment, warning, vulnerability, and law enforcement investigation and response entity. The NIPC provides timely warnings of international threats, comprehensive analysis and law enforcement investigation and response.

NIS Attack
NIS Attack refers to the intrusion to the Network Information System (NIS), which maintains a distributed database of password tables, group files, host tables, and other information that systems on a network can share. An attacker who can guess the name of your NIS domain and can send a NIS request to the NIS server can get a copy of your password information.

NIST: National Institute of Standards and Technology
National Institute of Standards and Technology (NIST) is a unit of the US Commerce Department. Formerly known as the National Bureau of Standards, NIST promotes and maintains measurement standards. It also has active programs for encouraging and assisting industry and science to develop and use these standards.

NMAP: Network Mapper
Nmap ("Network Mapper") is a free open source utility that can utilize a FTP bounce attack to scan other servers for network exploration or security auditing. It was designed to rapidly scan large networks, although it works fine against single hosts. Nmap uses raw IP packets in novel ways to determine what hosts are available on the network, what services (application name and version) those hosts are offering, what operating systems (and OS versions) they are running, what type of packet filters/firewalls is in use, and dozens of other characteristics. Nmap runs on most types of computers and both console and graphical versions are available on: www.insecure.org/nmap.

Node Spoofing
Node spoofing techniques can be used to greatly simplify routing design.

Nonce
In information technology, nonce is a random or non-repeating parameter value that is included in data exchanged by a protocol, usually for the purpose of guaranteeing liveness and thus detecting and protecting against replay attacks. A nonce can be a time stamp, a visit counter on a Web page, or a special marker intended to limit or prevent the unauthorized replay or reproduction of a file.

Non-Repudiation
Non-repudiation is the concept of ensuring that a contract, especially one agreed to via the Internet, cannot later be denied by one of the parties involved. In regard to digital security, non-repudiation means that it can be verified that the sender and the recipient were, in fact, the parties who claimed to send or receive the message, respectively. In other words, non-repudiation is the ability for a system to prove that a specific user and only that specific user sent a message and that it hasn't been modified.

Non-Repudiation Service
Non-repudiation Service is a security service that provides protection against false denial of involvement in a communication.

Npasswd
Npasswd, a replacement for the passwd utility on UNIX platforms, subjects user passwords to stringent guessability checks to decrease the chance of users choosing vulnerable passwords. It addresses other deficiencies found of standard password change programs. Npasswd is designed to replace the programs passwd, chfn and chsh.

NSA: National Security Agency
National Security Agency is a U.S. government agency responsible for protecting national information systems and producing foreign intelligence information.

NSAKEY
NSAKEY is a variable name discovered in Windows NT 4 Service Pack 5 (which had been released unstripped of its symbolic debugging data) in August 1999 by Andrew D. Fernandes of Cryptonym Corporation. That variable contained a 1024-bit public key.

Nslookup
Nslookup is a command-line utility for querying Domain Name System (DNS) name servers.

NTBugtraq
NTBugtraq is a mailing list for Microsoft Windows security issues.

NTLM: NT LAN Manager
NT LAN Manager(NTLM), now called Integrated Windows Authentication(IWA), is the authentication protocol used by Microsoft Windows NT. Like certain other protocols, IWA sits on top of HTTP. Web-browsing software uses it as a single sign-on mechanism, so browsing users can transparently log onto web services using their Microsoft Windows credentials. Microsoft developed IWA, and it occurs mostly in Microsoft products, though other sets of software have implemented it as well, as in the Mozilla Firefox web-browser, the Apache web-server and the shell utility cURL.

Ntrights
Ntrights is a tool for assigning rights to Microsoft Windows NT users or groups.

Nuke Attack or Nuking
Nuke attack, also known as "nuking", "blue bomb" or "WinNuke", is a technique for causing the Windows operating system of someone you're communicating with to crash or suddenly terminate. The "blue bomb" is actually an out-of-band network packet containing information that the operating system can't process. This condition causes the operating system to "crash" or terminate prematurely.

NULL Encryption Algorithm
NULL Encryption Algorithm, as defined in IETF RFC 2410, does nothing to transform plaintext data; that is, a no-op. It originated because of IPsec ESP, which always specifies the use of an encryption algorithm to provide confidentiality. The NULL encryption algorithm is a convenient way to represent the option of not applying encryption in ESP (or in any other context where this is needed).

Null Session
Known as Anonymous Logon, Null Session is a way of letting an anonymous user retrieve information such as user names and shares over the network or connect without authentication. It is used by applications such as explorer.exe to enumerate shares on remote servers.

Null session attack
Null session attack is an exploit that uses unauthenticated NetBIOS connections to enumerate a target host.

Nym server: pseudonym server
Nym server, also known as pseudonym server, is a server that provides an untraceable e-mail address, such that neither the nym server operator nor the operators of the remailers involved can discover which nym corresponds to which real identity.