Tenable Nessus is a world-leader in active vulnerability scanners. It features high-speed discovery, configuration auditing, asset profiling, sensitive data discovery, and vulnerability analysis of your security posture. Nessus scanners may be distributed throughout an entire enterprise, inside DMZs, and across physically separate networks. It is free of charge for personal use in a non-enterprise environment.
nsat is a fast, stable bulk security scanner designed to audit remote network services and check for versions, security problems, gather information about the servers and the machine, and much more. Unlike many other auditing tools, it can collect information about services independently of vulnerabilities, which makes it less dependent on frequent updates as new vulnerabilities are found.
Network Time Tools (NTT) is a set of network tools designed to provide monitoring of a network and the services on that network, and provide various reports on the hosts/services and optional alerts via email, pager, and cellphones. It comes with a protocol scanner, a bandwidth measurement tool, and a CGI front end that can handle a regular browser or WAP-enabled cellphones via WML.
Nmap ("Network Mapper") is a utility for network exploration, administration, and security auditing. It uses IP packets in novel ways to determine which hosts are available online (host discovery), which TCP/UDP ports are open (port scanning), and what applications and services are listening on each port (version detection). It can also identify remote host OS and device types via TCP/IP fingerprinting. Nmap offers flexible target and port specifications, decoy/stealth scanning for firewall and IDS evasion, and highly optimized timing algorithms for fast scanning.
NSA Security-enhanced Linux is a set of patches to the Linux kernel and some utilities to incorporate a strong, flexible mandatory access control architecture into the major subsystems of the kernel. It provides a mechanism to enforce the separation of information based on confidentiality and integrity requirements, which allows threats of tampering and bypassing of application security mechanisms to be addressed and enables the confinement of damage that can be caused by malicious or flawed applications. It includes a set of sample security policy configuration files designed to meet common, general-purpose security goals.
NSBD (Not-So-Bad Distribution) is an automated Web-based distribution system that is designed for distributing free software on the internet, where users cannot trust the network and cannot entirely trust the maintainers of software. NSBD authenticates packages with GNU Privacy Guard (GnuPG) or "Pretty Good(Tm) Privacy" (PGP(Tm)) digital signatures so users can be assured that packages have not been tampered with, and it limits the maintainer to only update selected files and directories on the user's computer. NSBD's focus is on security, leaving as much control as is practical in the users' hands. Network transfers are done with http or rsync.
The OpenCA Project is a collaborative effort to develop a robust, full-featured and Open Source out-of-the-box Certification Authority implementing the most used protocols with full-strength cryptography world-wide. OpenCA is based on many Open-Source Projects. Among the supported software is OpenLDAP, OpenSSL, Apache Project, Apache mod_ssl.