CRM
SugarCRM
Being part of a community allows you to borrow something you might need, like CRM software. A US-based company with around 150 employees, SugarCRM is a popular and broad application.
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Communications and networking
Wireshark
Wireshark is a network protocol analyser, which runs on Windows, Linux and OS X. Wireshark is popular and has a rich feature set.
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Snort
Snort is a network intrusion prevention system that will actively block or passively detect a range of threats. Snort is owned and maintained by Sourcefire.
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Netcat
Netcat is a feature rich network and debugging tool. It runs from the command line.
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Kismet
Kismet is a packet sniffer, and network detector for 802.11 wireless networks. Versions are available for Linux, OS X and Windows.
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Tcpdump
Tcpdump is a packet sniffer that runs from the command line and is available for Windows and Mac OS X systems. For tips on using Tcpdump, check out the video from ZDNet.com.au's sister site TechRepublic.
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Asterisk
Asterisk is a popular open source PBX and telephony platform. It's the basis for a diverse range of commercial PBX systems.
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Utilities
Bugzilla
Bugzilla is a bug tracking system designed to help you manage the software development process. It comes from the Mozilla Foundation.
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Wine
Wine allows Windows applications to be ported to Linux. Wine has gained popularity through its ability to port Photoshop onto the Linux platform, along with a range of other applications.
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SeaMonkey
SeaMonkey is an internet application suite from Mozilla. It contains a web browser, an email and news client and a HTML editor.
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FileZilla
FileZilla is an open source file transfer protocol (FTP) program from Mozilla. FileZilla is available in several languages.
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Hypervisors
KVM
The Kernel-based Virtual Machine (KVM) is a visualisation system for the Linux kernel. It is maintained by Qumranet, which is now owned by open-source giant Red Hat.
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Xen
Finding its commercial implementation as Citrix XenServer, Xen is a long-standing open source hypervisor.
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All images credited to their respective owners.
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Some people think if it is free that there must be something wrong it.
I knew someone who had a computer where the mouse did not work. He then bought a whole new operating system. And it was only the mouse that needed cleaning.
He said "Oh I've got windows XP Professional instead of the home version. It must be better."