Below i list some very usefull but free open source software:
Network Stuff
M0n0wall - Router
PFSense - Router (Based on M0n0wall)
Smoothwall - Router
FreeNAS - NAS Server
Untangle - Webfilter
CloneZilla - Hard Drive/Network Cloning
Nagios - Network Monitoring
WireShark - Protocal Analyzer
Real VNC - Remote Support Tool
FOG - Network Cloning tool
ThinStation - Thin Client
Back-Up / Restoring Software
Zmanda Open Source Backup – Free Open Source Backup/Restore
Telephony Stuff
TrixBox - IP PBX
HUD - Telephone Operator panel
AskoziaPBX - OpenSource IP PBX based on M0n0wall+Astrisk Code
Software
OpenOffice - MS Office alternative
AVG - AntiVirus
InfraRecorder - CD Burning Software
7-Zip - WinZip Alternative
NotePad++ - MS NotePad powerfull Alternative
Thunderbird - outlook alternative
FireFox - Internet Explorer Alternative
Internet/CRM’s
Sugar CRM - Free Web Based CRM
E-Mail Servers
Open-Xchange - MS Exchange alternative
Mail Enable - Free Edition of MailEnables email server
Operating systems
Ubuntu – Windows Alternative
OpenSUSE - Windows Alternative
Operating System Management
WebMin – Web based GUI for system Management
