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Free, open source package designed to detect Trojans, viruses, malware and other malicious threats. Included in the software, which now comes preinstalled in several Linux distributions, are a multithreaded scanning daemon, command line utilities for on-demand file scanning, and an intelligent tool for automatic signature updates. Of particular note for past or current Windows users is that the core ClamAV library is also used in
Immunet 3.0, a sister solution for Microsoft's operating system.
Snort
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Also offered by Sourcefire is Snort, an open source network intrusion prevention and detection system that combines the benefits of signature, protocol and anomaly-based inspection. With millions of downloads and more than 300,000 registered users to its credit, Snort is the most widely deployed such technology worldwide, Sourcefire says.
Wireshark
Wireshark is a network protocol analyzer that lets you capture and interactively browse the traffic running on a computer network. The software runs not just on Linux but on Windows, OS X, Solaris, FreeBSD and NetBSD, as well. Captured network data can be browsed via GUI or via the TTY-mode TShark utility.
John the Ripper
John the Ripper is a free and open source password cracker that can help you detect weak passwords. It's distributed primarily in source code form, but native "pro" versions are available for both Linux and Macs as well.
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Another similar tool, incidentally, is
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NMAP
Short for "Network Mapper," Nmap is a free and open source utility for network exploration or security auditing, but it can also be useful for network inventory, managing service upgrade schedules, and monitoring host or service uptime. Nmap runs on all major computer operating systems. Oddly, it has even been featured in movies including The Matrix Reloaded, The Bourne Ultimatum and The Girl with the Dragon Tattoo.
Chkrootkit
Chkrootkit is a free tool designed to check locally for signs of a rootkit infection on your Linux machine. The free software is a very popular choice, but
Rootkit Hunter is another, like-minded alternative.
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With more than five million downloads to date, Nessus is one of the most popular vulnerability scanners in the world, its makers say. The proprietary software features high-speed discovery, configuration auditing, asset profiling, sensitive data discovery and vulnerability analysis of your security posture. Personal use of Nessus is free.
There are, of course, countless other security tools for Linux out there, many of them excellent as well.
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