Nessus

Nessus is one of the most popular and capable vulnerability scanners, particularly for UNIX systems. It was initially free and open source, but they closed the source code in 2005 and removed the free "Registered Feed" version in 2008. It now costs $1,200 per year, which still beats many of its competitors. A free “Home Feed” is also available, though

it is limited and only licensed for home network use. Nessus is constantly updated, with more than 46,000 plugins. Key features include remote and local (authenticated) security checks, a client/server architecture with a web-based interface, and an embedded scripting language for writing your own plugins or understanding the existing ones. The open-source version of Nessus was forked by a group of users who still develop it under the OpenVAS name.

Nessus® is the world’s most widely-deployed vulnerability and configuration assessment product with more than five million downloads to date. Nessus 5 features high-speed discovery, configuration auditing, asset profiling, sensitive data discovery, patch management integration, and vulnerability analysis of your security posture with features that enhance usability, effectiveness, efficiency, and communication with all parts of your organization.

Microsoft Windows

Windows XP, 2003, Vista, 2008 & 7 (32 bits):
Nessus-5.0.1-i386.msi (11696 KB)

Windows XP, 2003, Vista, 2008 & 7 (64 bits):
Nessus-5.0.1-x86_64.msi (13027 KB)

Mac OS X

Mac OS X (10.6 and 10.7):
Nessus-5.0.1.dmg.gz (46923 KB)

Mac OS X 10.8 (Mountain Lion):
Nessus-5.0.1-ml.dmg.gz (47076 KB)

Linux

Debian 6.0 (32 bits):
Nessus-5.0.1-debian6_i386.deb (22390 KB)

Debian 6.0 (64 bits):
Nessus-5.0.1-debian6_amd64.deb (24917 KB)

Red Hat ES 4 / CentOS 4:
Nessus-5.0.1-es4.i386.rpm (20770 KB)

Red Hat ES 5 (32 bits) / CentOS 5 / Oracle Linux 5 (including Unbreakable Enterprise Kernel):
Nessus-5.0.1-es5.i386.rpm (21768 KB)

Red Hat ES 5 (64 bits) / CentOS 5 / Oracle Linux 5 (including Unbreakable Enterprise Kernel):
Nessus-5.0.1-es5.x86_64.rpm (24029 KB)

Red Hat ES 6 (32 bits) / CentOS 6:
Nessus-5.0.1-es6.i686.rpm (19860 KB)

Red Hat ES 6 (64 bits) / CentOS 6:
Nessus-5.0.1-es6.x86_64.rpm (22183 KB)

Fedora Core 16 (32 bits):
Nessus-5.0.1-fc16.i686.rpm (21423 KB)

Fedora Core 16 (64 bits):
Nessus-5.0.1-fc16.x86_64.rpm (21890 KB)

SuSE 10 Enterprise (64 bits):
Nessus-5.0.1-suse10.x86_64.rpm (22612 KB)

SuSE 11 Enterprise (32 bits):
Nessus-5.0.1-suse11.i586.rpm (19801 KB)

SuSE 11 Enterprise (64 bits):
Nessus-5.0.1-suse11.x86_64.rpm (21352 KB)

Ubuntu 8.04 (32 bits):
Nessus-5.0.1-ubuntu804_i386.deb (21630 KB)

Ubuntu 8.04 (64 bits):
Nessus-5.0.1-ubuntu804_amd64.deb (23888 KB)

Ubuntu 9.10 / Ubuntu 10.04 (32 bits):
Nessus-5.0.1-ubuntu910_i386.deb (22433 KB)

Ubuntu 9.10 / Ubuntu 10.04 (64 bits):
Nessus-5.0.1-ubuntu910_amd64.deb (24910 KB)

Ubuntu 10.10 (32 bits):
Nessus-5.0.1-ubuntu1010_i386.deb (22503 KB)

Ubuntu 10.10 (64 bits):
Nessus-5.0.1-ubuntu1010_amd64.deb (25104 KB)

Ubuntu 11.10 / Ubuntu 12.04 (32 bits):
Nessus-5.0.1-ubuntu1110_i386.deb (24668 KB)

Ubuntu 11.10 / Ubuntu 12.04 (64 bits):
Nessus-5.0.1-ubuntu1110_amd64.deb (25298 KB)